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Symbiosis. In the Central American bullthorn acacias—"Acacia sphaerocephala", "Acacia cornigera" and "Acacia collinsii" — some of the spiny stipules are large, swollen and hollow. These afford shelter for several species of "Pseudomyrmex" ants, which feed on extrafloral nectaries on the leaf-stalk and small lipid-rich food-bodies at the tips of the leaflets called Beltian bodies. In return, the ants add protection to the plant against herbivores. Some species of ants will also remove competing plants around the acacia, cutting off the offending plants' leaves with their jaws and ultimately killing them. Other associated ant species appear to do nothing to benefit their hosts. Similar mutualisms with ants occur on "Acacia" trees in Africa, such as the whistling thorn acacia. The acacias provide shelter for ants in similar swollen stipules and nectar in extrafloral nectaries for their symbiotic ants, such as "Crematogaster mimosae". In turn, the ants protect the plant by attacking large mammalian herbivores and stem-boring beetles that damage the plant.
The predominantly herbivorous spider "Bagheera kiplingi", which is found in Central America and Mexico, feeds on nubs at the tips of the acacia leaves, known as Beltian bodies, which contain high concentrations of protein. These nubs are produced by the acacia as part of a symbiotic relationship with certain species of ant, which also eat them. Pests. In Australia, "Acacia" species are sometimes used as food plants by the larvae of hepialid moths of the genus "Aenetus" including "A. ligniveren". These burrow horizontally into the trunk then vertically down. Other Lepidoptera larvae which have been recorded feeding on "Acacia" include brown-tail, "Endoclita malabaricus" and turnip moth. The leaf-mining larvae of some bucculatricid moths also feed on "Acacia"; "Bucculatrix agilis" feeds exclusively on "Acacia horrida" and "Bucculatrix flexuosa" feeds exclusively on "Acacia nilotica". Acacias contain a number of organic compounds that defend them from pests and grazing animals. Uses. Use as human food. Acacia seeds are often used for food and a variety of other products.
In Myanmar, Laos, and Thailand, the feathery shoots of "Acacia pennata" (common name "cha-om", ชะอม and "su pout ywet" in Burmese) are used in soups, curries, omelettes, and stir-fries. Gum. Various species of acacia yield gum. True gum arabic is the product of "Acacia senegal", abundant in dry tropical West Africa from Senegal to northern Nigeria. "Acacia nilotica" (syn. "Acacia arabica") is the gum arabic tree of India, but yields a gum inferior to the true gum arabic. Gum arabic is used in a wide variety of food products, including some soft drinks and confections. The ancient Egyptians used acacia gum in paints. The gum of "Acacia xanthophloea" and "Acacia karroo" has a high sugar content and is sought out by the lesser bushbaby. "Acacia karroo" gum was once used for making confectionery and traded under the name "Cape Gum". It was also used medicinally to treat cattle suffering poisoning by "Moraea" species. Uses in folk medicine. "Acacia" species have possible uses in folk medicine. A 19th-century Ethiopian medical text describes a potion made from an Ethiopian species (known as "grar") mixed with the root of the "tacha", then boiled, as a cure for rabies.
An astringent medicine high in tannins, called catechu or cutch, is procured from several species, but more especially from "Senegalia catechu" (syn. "Acacia catechu"), by boiling down the wood and evaporating the solution so as to get an extract. The catechu extract from "A. catechu" figures in the history of chemistry in giving its name to the catechin, catechol, and catecholamine chemical families ultimately derived from it. Ornamental uses. A few species are widely grown as ornamentals in gardens; the most popular perhaps is "A. dealbata" (silver wattle), with its attractive glaucous to silvery leaves and bright yellow flowers; it is erroneously known as "mimosa" in some areas where it is cultivated, through confusion with the related genus "Mimosa". Another ornamental acacia is the fever tree. Southern European florists use "A. baileyana", "A. dealbata", "A. pycnantha" and "A. retinodes" as cut flowers and the common name there for them is mimosa. Ornamental species of acacias are also used by homeowners and landscape architects for home security. The sharp thorns of some species are a deterrent to trespassing, and may prevent break-ins if planted under windows and near drainpipes. The aesthetic characteristics of acacia plants, in conjunction with their home security qualities, makes them a reasonable alternative to constructed fences and walls.
Perfume. "Acacia farnesiana" is used in the perfume industry due to its strong fragrance. The use of acacia as a fragrance dates back centuries. Symbolism and ritual. Egyptian mythology has associated the acacia tree with characteristics of the tree of life, such as in the Myth of Osiris and Isis. Several parts (mainly bark, root, and resin) of "Acacia" species are used to make incense for rituals. Acacia is used in incense mainly in India, Nepal, and China including in its Tibet region. Smoke from acacia bark is thought to keep demons and ghosts away and to put the gods in a good mood. Roots and resin from acacia are combined with rhododendron, acorus, cytisus, salvia, and some other components of incense. Both people and elephants like an alcoholic beverage made from acacia fruit. According to Easton's Bible Dictionary, the acacia tree may be the "burning bush" (Exodus 3:2) which Moses encountered in the desert. Also, when God gave Moses the instructions for building the Tabernacle, he said to "make an ark" and "a table of acacia wood" (Exodus 25:10 & 23, Revised Standard Version). Also, in the Christian tradition, Christ's crown of thorns is thought to have been woven from acacia.
Acacia was used for Zulu warriors' iziQu (or isiKu) beads, which passed on through Robert Baden-Powell to the Scout movement's Wood Badge training award. In Russia, Italy, and other countries, it is customary to present women with yellow mimosas (among other flowers) on International Women's Day (March 8). These "mimosas" may be from "A. dealbata" (silver wattle). In 1918, May Gibbs, the popular Australian children's author, wrote the book 'Wattle Babies', in which a third-person narrator describes the lives of imaginary inhabitants of the Australian forests (the 'bush'). The main characters are the Wattle Babies, who are tiny people that look like acacia flowers and who interact with various forest creatures. Gibbs wrote "Wattle Babies are the sunshine of the Bush. In Winter, when the sky is grey and all the world seems cold, they put on their yellowest clothes and come out, for they have such cheerful hearts." Gibbs was referring to the fact that an abundance of acacias flower in August in Australia, in the midst of the southern hemisphere winter.
Tannin. The bark of various Australian species, known as wattles, is very rich in tannin and forms an important article of export; important species include "A. pycnantha" (golden wattle), "A. decurrens" (tan wattle), "A. dealbata" (silver wattle) and "A. mearnsii" (black wattle). Black wattle is grown in plantations in South Africa and South America. The pods of "A. nilotica" (under the name of "neb-neb"), and of other African species, are also rich in tannin and used by tanners. In Yemen, the principal tannin substance was derived from the leaves of the salam-tree ("Acacia etbaica"), a tree known locally by the name "qaraẓ" ("garadh"). A bath solution of the crushed leaves of this tree, into which raw leather had been inserted for prolonged soaking, would take only 15 days for curing. The water and leaves, however, required changing after seven or eight days, and the leather needed to be turned over daily. Wood. Some "Acacia" species are valuable as timber, such as "A. melanoxylon" (blackwood) from Australia, which attains a great size; its wood is used for furniture, and takes a high polish; and "A. omalophylla" (myall wood, also Australian), which yields a fragrant timber used for ornaments. "A. seyal" is thought to be the shittah-tree of the Bible, which supplied shittim-wood. According to the Book of Exodus, this was used in the construction of the Ark of the Covenant. "A. koa" from the Hawaiian Islands and "A. heterophylla" from Réunion are both excellent timber trees. Depending on abundance and regional culture, some "Acacia" species (e.g. "A. fumosa") are traditionally used locally as firewoods. It is also used to make homes for different animals.
Pulpwood. In Indonesia (mainly in Sumatra) and in Malaysia (mainly in Sabah), plantations of "A. mangium" are being established to supply pulpwood to the paper industry. Acacia wood pulp gives high opacity and below average bulk paper. This is suitable in lightweight offset papers used for Bibles and dictionaries. It is also used in paper tissue where it improves softness. Land reclamation. Acacias can be planted for erosion control, especially after mining or construction damage. Ecological invasion. For the same reasons it is favored as an erosion-control plant, with its easy spreading and resilience, some varieties of acacia are potentially invasive species. At least fourteen "Acacia" species introduced to South Africa are categorized as invasive, due to their naturally aggressive propagation. One of the most globally significant invasive acacias is black wattle "A. mearnsii", which is taking over grasslands and abandoned agricultural areas worldwide, especially in moderate coastal and island regions where mild climate promotes its spread. Australian/New Zealand Weed Risk Assessment gives it a "high risk, score of 15" rating and it is considered one of the world's 100 most invasive species.
Extensive ecological studies should be performed before further introduction of acacia varieties, as this fast-growing genus, once introduced, spreads quickly and is extremely difficult to eradicate. Phytochemistry. Cyanogenic glycosides. Nineteen different species of "Acacia" in the Americas contain cyanogenic glycosides, which, if exposed to an enzyme which specifically splits glycosides, can release hydrogen cyanide (HCN) in the "leaves". This sometimes results in the poisoning death of livestock. If fresh plant material spontaneously produces 200 ppm or more HCN, then it is potentially toxic. This corresponds to about 7.5 μmol HCN per gram of fresh plant material. It turns out that, if acacia "leaves" lack the specific glycoside-splitting enzyme, then they may be less toxic than otherwise, even those containing significant quantities of cyanic glycosides. Some "Acacia" species containing cyanogens include "Acacia erioloba", "A. cunninghamii", "A. obtusifolia", "A. sieberiana", and "A. sieberiana" var. "woodii" Famous acacias. The Arbre du Ténéré in Niger was the most isolated tree in the world, about from any other tree. The tree was knocked down by a truck driver in 1973. In Nairobi, Kenya, the Thorn Tree Café is named after a Naivasha thorn tree ("Acacia xanthophloea") in its centre. Travelers used to pin notes to others to the thorns of the tree. The current tree is the third of the same variety.
Acapulco Acapulco de Juárez (), commonly called Acapulco ( , ; ), is a city and major seaport in the state of Guerrero on the Pacific Coast of Mexico, south of Mexico City. Located on a deep, semicircular bay, Acapulco has been a port since the early colonial period of Mexico's history. It is a port of call for shipping and cruise lines running between Panama and San Francisco, California, United States. The city of Acapulco is the largest in the state, far larger than the state capital Chilpancingo. Acapulco is also Mexico's largest beach and balneario resort city. Acapulco de Juárez, Guerrero is the municipal seat of the municipality of Acapulco, Guerrero. The city is one of Mexico's oldest beach resorts, coming into prominence in the 1940s through the 1960s as a getaway for Hollywood stars and millionaires. Acapulco was once a popular tourist resort, but due to a massive upsurge in gang violence and homicide numbers since 2014, Acapulco no longer attracts many foreign tourists, and most now only come from within Mexico itself. It is both the ninth deadliest city in Mexico and the tenth-deadliest city in the world as of 2022; the US government has warned its citizens not to travel there. In 2016 there were 918 murders, and the homicide rate was one of the highest in the world: 103 in every 100,000. In September 2018, the city's entire police force was disarmed by the military, due to suspicions that it had been infiltrated by drug gangs.
The resort area is divided into three parts: the north end of the bay and beyond is the "traditional" area, which encompasses the area from "Parque Papagayo" through the and onto the beaches of "Caleta" and "Caletilla", the main part of the bay known as " ('golden zone' in Spanish), where the famous in the mid-20th century vacationed, and the south end, " ('diamond' in Spanish), which is dominated by newer luxury high-rise hotels and condominiums. The name "Acapulco, Guerrero" comes from Nahuatl language "Aca-pōl-co", and means "where the reeds were destroyed or washed away" or "at the big reeds", which inspired the city's seal, which is an Aztec-type glyph showing two hands breaking reeds. The "de Juárez" was added to the official name in 1885 to honor Benito Juárez, former president of Mexico (1806–1872). The island and municipality of Capul, in the Philippines, derives its name from Acapulco, Guerrero. Acapulco, Guerrero was the eastern end of the trans-Pacific sailing route from Acapulco to Manila, in what was then a Spanish colony.
History. Pre-Columbian. By the 8th century, around the Acapulco Bay area, there was a small culture which would first be dominated by the Olmecs, then by a number of others during the pre-Hispanic period before it ended in the 1520s. At Acapulco Bay itself, there were two Olmec sites, one by Playa Larga and the other on a hill known as "El Guitarrón". Olmec influence caused the small spread-out villages here to coalesce into larger entities and build ceremonial centers. Later, Teotihuacan influence came to the area via Cuernavaca and Chilpancingo. Then Mayan influence arrived from the Isthmus of Tehuantepec and through what is now Oaxaca. This history is known through the archaeological artifacts that have been found here, especially at "Playa Hornos, Pie de la Cuesta", and "Tambuco". In the 11th century, new waves of migration of Nahuas, including the "Coixcas", came through here. These people were the antecedents of the Aztecs. In the later 15th century, after four years of military struggle, Acapulco became part of the Aztec Empire during the reign of Ahuizotl (1486–1502). It was annexed to a tributary province named "Tepecuacuilco". However, this was only transitory, as the Aztecs could only establish an unorganized military post at the city's outskirts. The city was in territory under control of the "Yopis", who continued defending it and living there until the arrival of the Spanish in the 1520s. 16th century.
There are two stories about how Acapulco bay was discovered by Europeans. The first states that two years after the Spanish conquest of the Aztec Empire, Hernán Cortés sent explorers west to find gold. The explorers had subdued this area after 1523, and Captain Saavedra Cerón was authorized by Cortés to found a settlement here. The other states that the bay was discovered on December 13, 1526, by a small ship named the El Tepache Santiago captained by Santiago Guevara. The first encomendero was established in 1525 at "Cacahuatepec", which is still part of the modern Acapulco municipality. In 1531, a number of Spaniards, most notably Juan Rodriguez de Villafuerte, left the Oaxaca coast and founded the village of Villafuerte where the city of Acapulco now stands. Villafuerte was unable to subdue the local native peoples, and this eventually resulted in the Yopa Rebellion in the region of "Cuautepec". Hernán Cortés was obligated to send Vasco Porcayo to negotiate with the indigenous people giving concessions. The province of Acapulco became the encomendero of Rodriguez de Villafuerte who received taxes in the form of cocoa, cotton and corn.
Cortés established Acapulco as a major port by the early 1530s, with the first major road between Mexico City and the port constructed by 1531. The wharf, named Marqués, was constructed by 1533 between Bruja Point and Diamond Point. Soon after, the area was made an "alcadia" (major province or town). Spanish trade in the Far East would give Acapulco a prominent position in the economy of New Spain. In 1550, thirty Spanish families were sent to live here from Mexico City to have a permanent base of European residents. Galleons started arriving in Acapulco from Asia by 1565. Acapulco would become the second most important port, after Veracruz, due to its direct trade with the Philippines. This trade would focus on the yearly Manila-Acapulco Galleon trade, which was the nexus of all kinds of communications between New Spain, Europe and Asia. In 1573, the port was granted the monopoly of the Manila trade. 17th–19th centuries. On January 25, 1614, a delegation led by samurai Hasekura Tsunenaga, which included over one hundred Japanese Christians as well as twenty-two samurai under the shōgun Tokugawa Ieyasu, arrived from Japan to Acapulco as part of a mission to form closer relations with Catholic Europe. A fight soon broke out in which a Japanese samurai stabbed a Spanish colonial soldier in Acapulco. This was witnessed and recorded by historian Chimalpahin, who was the grandson of an Aztec nobleman. Some of Tsunenaga's delegation would stay and marry with the locals.
The galleon trade made its yearly run from the mid-16th century until the early 19th. The luxury items it brought to New Spain attracted the attention of English and Dutch pirates, such as Francis Drake, Henry Morgan and Thomas Cavendish, who called it "The Black Ship". A Dutch fleet invaded Acapulco in 1615, destroying much of the town before being driven off. The Fort of San Diego was built the following year to protect the port and the cargo of arriving ships. The fort was destroyed by an earthquake in 1776 and was rebuilt between 1778 and 1783. At the beginning of the 19th century, King Charles IV declared Acapulco a Ciudad Official and it became an essential part of the Spanish Crown. However, not long after, the Mexican War of Independence began. In 1810, José María Morelos y Pavón attacked and burnt down the city, after he defeated royalist commander Francisco Parés at the Battle of Tres Palos. The independence of Mexico in 1821 ended the run of the Manila Galleon. Acapulco's importance as a port recovered during the California Gold Rush in the mid-19th-century, with ships going to and coming from Panama stopping here. This city was besieged on 19 April 1854 by Antonio López de Santa Anna after Guerrero's leadership had rebelled by issuing the Plan de Ayutla. After an unsuccessful week of fighting, Santa Anna retreated. 20th century.
In 1911, revolutionary forces took over the main plaza of Acapulco. In 1920, the Prince of Wales (the future King Edward VIII) visited the area. Impressed by what he saw, he recommended the place to his compatriots in Europe, making it popular with the elite there. Much of the original hotel and trading infrastructure was built by a businessman named Albert B. Pullen from Corrigan, Texas, in the area now known as Old Acapulco. In 1933, Carlos Barnard started the first section of "Hotel El Mirador", with 12 rooms on the cliffs of La Quebrada. Albert Pullen built the "Las Americas Hotel". In the late 1930s, “La Fraccionadora de Acapulco, S.A.” (FASA), consisting of William Pullen, Anacleto Martínez, Juan M. Salcedo, and Wolf Schoenburg, who was especially instrumental, started tourism development in earnest. In the mid-1940s, the first commercial wharf and warehouses were built. In the early 1950s, President Miguel Alemán Valdés upgraded the port's infrastructure, installing electrical lines, drainage systems, roads and the first highway to connect the port with Mexico City.
The economy grew and foreign investment increased with it. During the 1950s, Acapulco became the fashionable place for millionaire Hollywood stars such as Elizabeth Taylor, Frank Sinatra, Eddie Fisher and Brigitte Bardot. The 1963 Hollywood movie "Fun in Acapulco", starring Elvis Presley, is set in Acapulco although the filming took place in the United States. Former swing musician Teddy Stauffer, the so-called "Mister Acapulco", was a hotel manager ("Villa Vera", "Casablanca"), who attracted many celebrities to Acapulco. From a population of only 4,000 or 5,000 in the 1940s, by the early 1960s, Acapulco had a population of about 50,000. In 1958, the Diocese of Acapulco was created by Pope Pius XII. It became an archdiocese in 1983. During the 1960s and 1970s, new hotel resorts were built, and accommodation and transport were made cheaper. It was no longer necessary to be a millionaire to spend a holiday in Acapulco; the foreign and Mexican middle class could now afford to travel here. However, as more hotels were built in the south part of the bay, the old hotels of the 1950s lost their grandeur. For the 1968 Summer Olympics in neighboring Mexico City, Acapulco hosted the sailing (then yachting) events.
In the 1970s, there was a significant expansion of the port. The Miss Universe 1978 pageant took place in the city. In 1983, singer-songwriter Juan Gabriel wrote the song "Amor eterno", which pays homage to Acapulco. The song was first and most famously recorded by Rocío Dúrcal. Additionally, Acapulco is the hometown of actress, singer, and comedian Aída Pierce, who found fame during the 1980s, 1990s and the first decade of the 21st century. The tollway known as the "Ruta del Sol" was built during the 1990s, crossing the mountains between Mexico City and Acapulco. The journey takes only about three-and-a-half hours, making Acapulco a favorite weekend destination for Mexico City inhabitants. It was in that time period that the economic impact of Acapulco as a tourist destination increased positively, and as a result new types of services emerged, such as the Colegio Nautilus. This educational project, backed by the state government, was created for the families of local and foreign investors and businessmen living in Acapulco who were in need of a bilingual and international education for their children.
The port continued to grow and in 1996, a new private company, API Acapulco, was created to manage operations. This consolidated operations and now Acapulco is the major port for car exports to the Pacific. The city was devastated by Hurricane Pauline in 1997. The storm stranded tourists and left more than 100 dead in the city. Most of the victims were from the shantytowns built on steep hillsides that surround the city. Other victims were swept away by thirty-foot (9 m) waves and winds. The main road, Avenida Costera, became a fast-moving river of sludge in depth. 21st century. In the 21st century, the Mexican Drug War has had a negative effect on tourism in Acapulco as rival drug traffickers fight each other for the Guerrero coast route that brings drugs from South America as well as soldiers that have been fighting the cartels since 2006. A major gun battle between 18 gunmen and soldiers took place in the summer of 2009 in the Old Acapulco seaside area, lasting hours and killing 16 of the gunmen and two soldiers. This came after the 2009 swine flu pandemic outbreak earlier in the year nearly paralyzed the Mexican economy, forcing hotels to give discounts to bring tourists back. However, hotel occupancy for 2009 was down five percent from the year before. The death of Arturo Beltrán Leyva in December 2009 resulted in infighting among different groups within the Beltrán Leyva cartel.
Gang violence continued to plague Acapulco through 2010 and into 2011, most notably with at least 15 dying in drug-related violence on March 13, 2010, and another 15 deaths on January 8, 2011. Among the first incident's dead were six members of the city police and the brother of an ex-mayor. In the second incident, the headless bodies of 15 young men were found dumped near the Plaza Sendero shopping center. On August 20, 2011, Mexican authorities reported that five headless bodies were found in Acapulco, three of which were placed in the city's main tourist area and two of which were cut into multiple pieces. On February 4, 2013, six Spanish men were tied up and robbed and the six Spanish women with them were gang-raped by five masked gunmen who stormed a beach house on the outskirts of Acapulco, though after these accusations, none of the victims decided to press charges. On September 28, 2014, Mexican politician Braulio Zaragoza was gunned down at the "El Mirador" hotel in the city. He was the leader of the conservative opposition National Action Party (PAN) in southern Guerrero state. Several politicians have been targeted by drug cartels operating in the area. Investigations are under way, but no arrests have yet been made as of September 29. The insecurity due to individuals involved with drug cartels has cost the city of Acapulco its popularity among national and international tourists. It was stated by the "Dirección General de Aeronáutica Civil" that the number of international flyers coming to Acapulco decreased from 355,760 flyers registered in 2006 to 52,684 flyers in the year 2015, the number of international tourists flying to Acapulco dropped 85% in the interval of nine years. In 2018, the Mexican Armed Forces entered the city, placing it under occupation. The police department was disarmed after allegations of the latter being linked to the cartels.
Hurricane Otis. On October 25, 2023, Hurricane Otis, a Category 5 hurricane with 1-minute sustained winds of , caused widespread devastation throughout the city while making landfall nearby. Hurricane John. Hurricane John struck Acapulco and Mexico's Pacific coast in late September 2024 as a Category 3 hurricane, delivering powerful winds and extreme rainfall that led to widespread flooding and significant damage. Acapulco experienced nearly one meter of rainfall, resulting in submerged neighborhoods and serious disruptions. Roads became impassable due to landslides, and extensive power outages left tens of thousands without electricity across Guerrero and Oaxaca. Around 40,000 homes were damaged impacting over 150,000 residents. Geography. The city, located on the Pacific coast of Mexico in the state of Guerrero, is classified as one of the state's seven regions, dividing the rest of the Guerrero coast into the Costa Grande and the Costa Chica. Forty percent of the municipality is mountainous terrain; another forty percent is semi-flat; and the other twenty percent is flat. Elevation varies from sea level to . The highest peaks are "Potrero, San Nicolas", and "Alto Camarón". One major river runs through the municipality, the "Papagayo", along with a number of "arroyos" (streams). There are also two small lagoons, Tres Palos and Coyuca, along with a number of thermal springs.
Climate. Acapulco features a tropical wet and dry climate (Köppen: Aw): hot with distinct wet and dry seasons, with more even temperatures between seasons than resorts farther north in Mexico, but this varies depending on altitude. The warmest areas are next to the sea where the city is. Pacific hurricanes and tropical storms are threats from May through November; notably, the city was struck directly by Category 5 Hurricane Otis on October 25, 2023, which caused extensive damage. The forested area tends to lose leaves during the winter dry season, with evergreen pines in the highest elevations. Fauna consists mostly of deer, small mammals, a wide variety of both land and seabirds, and marine animals such as turtles. Oddly enough, January, its coolest month, also features its all-time record high. The temperature of the sea is quite stable, with lows of between January – March, and a high of in August. These sea surface temperatures are much warmer than those further north along the Pacific coast, and indeed warmer than most places further south, as sea surface temperatures begin to decline with proximity to the Southern Hemisphere's Humboldt Current.
Government. As the seat of a municipality, the city of Acapulco is the government authority for over 700 other communities, which together have a territory of 1,880.60 km2. This municipality borders the municipalities of Chilpancingo, Juan R Escudero (Tierra Colorada), San Marcos, Coyuca de Benítez with the Pacific Ocean to the south. The metropolitan area is made up of the municipalities of Acapulco de Juárez and Coyuca de Benitez. The area has a population () of 786,830. For the names and terms of some Acapulco mayors, you can check a List of municipal presidents of Acapulco. Demographics. Population. Acapulco is the most populated city in the state of Guerrero, according to the results of the II Population and Housing Census 2010 carried out by the National Institute of Statistics and Geography (INEGI) with a census date of June 12, 2010, The city had until then a total population of 673,479 inhabitants, of that amount, 324,746 were men and 348,733 women. It is considered the twenty-second most populous city in Mexico and the tenth most populous metropolitan area in Mexico. It is also the city with the highest concentration of population of the homonymous municipality, representing 85.25 percent of the 789,971 inhabitants. In the 2020 census of 658,609 people where counted in the locality and 779,566 in the municipality of Acapulco, a small drop from the last census.
The metropolitan area of Acapulco is made up of six towns in the municipality of Acapulco de Juárez and four in the municipality of Coyuca de Benítez. In agreement with the last count and official delimitation realized in 2010 altogether by the National Institute of Statistics and Geography, the National Council of Population and the Secretariat of Social Development, the metropolitan area of Acapulco grouped a total of 863,431 inhabitants in a surface of 3,538.5 km2, which placed it as the tenth most populated district in Mexico. <noinclude> Economy. Tourism is the main economic activity of the municipality and most of this is centered on Acapulco Bay. About seventy-three percent of the municipality's population is involved in commerce, most of it related to tourism and the port. Mining and manufacturing employ less than twenty percent and only about five percent is dedicated to agriculture. Industrial production is limited mostly to bottling, milk products, cement products, and ice and energy production. Agricultural products include tomatoes, corn, watermelon, beans, green chili peppers, and melons.
Tourism. Acapulco is one of Mexico's oldest coastal tourist destinations, reaching prominence in the 1950s as the place where Hollywood stars and millionaires vacationed on the beach in an exotic locale. In modern times, tourists in Acapulco have been facing problems with corrupt local police who steal money by extortion and intimidate visitors with threats of jail. The city is divided into three tourist areas. Traditional Acapulco is the old part of the port, where hotels like Hotel Los Flamingos, owned by personalities Johnny Weissmuller and John Wayne are located, is on the northern end of the bay. Anchored by attractions such as the beaches of Caleta and Caletilla, the cliff divers of La Quebrada, and the city square, known as "El Zocalo". The heyday of this part of Acapulco ran from the late 1930s until the 1960s, with development continuing through the 1980s. This older section of town now caters to a mostly middle-class, almost exclusively Mexican clientele, while the glitzier newer section caters to the Mexican upper classes, many of whom never venture into the older, traditional part of town.
Acapulco Dorado had its development between the 1950s and the 1970s, and is about 25 minutes from the Acapulco International Airport. It is the area that presents the most tourist influx in the port, runs through much of the Acapulco bay, from Icacos, passing through Costera Miguel Aleman Avenue, which is the main one, to Papagayo Park. It has several hotels, Acapulco Diamante, also known as Punta Diamante, is the newest and most developed part of the port, with investment having created one of the greatest concentrations of luxury facilities in Mexico, including exclusive hotels and resorts of international chains, residential complexes, luxury condominiums and private villas, spas, restaurants, shopping areas and a golf course. Starting at the Scenic Highway in Las Brisas, it includes Puerto Marqués and Punta Diamante and extends to Barra Vieja Beach. It is 10 minutes from the Acapulco International Airport. In this area, all along "Boulevard de las Naciones", almost all transportation is by car, limousine or golf cart.
Acapulco's reputation of a high-energy party town and the nightlife have long been draws of the city for tourists. From November to April, luxury liners stop here daily and include ships such as the , the , "Crystal Harmony", and all the Princess line ships. Despite Acapulco's international fame, most of its visitors are from central Mexico, especially the affluent from Mexico City. Acapulco is one of the embarkation ports for the Mexican cruise line Ocean Star Cruises. For the Christmas season of 2009, Acapulco received 470,000 visitors, most of whom are Mexican nationals, adding 785 million pesos to the economy. Eighty percent arrive by land and eighteen percent by air. The area has over 25,000 condominiums, most of which function as second homes for their Mexican owners. Acapulco is still popular with Mexican celebrities and the wealthy, such as Luis Miguel and Plácido Domingo, who maintain homes there. Problems. From the latter 20th century on, the city has also taken on other less-positive reputations. Some consider it a "passé" resort, eclipsed by the newer Cancún and Cabo San Lucas. Over the years, a number of problems have developed here, especially in the bay and the older sections of the city. The large number of wandering vendors on the beaches, who offer everything from newspapers to massages, are a recognized problem. It is a bother to tourists who simply want to relax on the beach, but the government says it is difficult to eradicate, as there is a lot of unemployment and poverty in the city. Around the city are many small shantytowns that cling to the mountainsides, populated by migrants who have come to the city looking for work. In the last decade, drug-related violence has caused massive problems for the local tourism trade.
Another problem is the garbage that has accumulated in the bay. Although 60.65 tons have recently been extracted from the bays of Acapulco and nearby Zihuatanejo, more needs to be done. Most of trash removal during the off seasons is done on the beaches and in the waters closest to them. However, the center of the bay is not touched. The reason trash winds up in the bay is that it is common in the city to throw it in streets, rivers and the bay itself. The most common items cleaned out of the bay are beer bottles and car tires. Acapulco has seen some success in this area, having several beaches receiving the high "blue flag" certifications for cleanliness and water quality. Cuisine. Acapulco's cuisine is very rich. The following are typical dishes from the region: Relleno is baked pork with a variety of vegetables and fruits such as potatoes, raisins, carrots and chiles. It is eaten with bread called "bolillo". Pozole is a soup with a salsa base (it can be white, red or green), hominy, meat that can be either pork or chicken and it is accompanied with "antojitos" (snacks) like tostadas, tacos and tamales. This dish is served as part of a weekly Thursday event in the city and the state, with many restaurants offering the meal with special entertainment, from bands to dancers to celebrity impersonators.
Attractions. Acapulco's main attraction is its nightlife, as it has been for many decades. Nightclubs change names and owners frequently. For example, Baby 'O has been open to the national and international public since 1976 and different celebrities have visited their installations such as Mexican singer Luis Miguel, Bono from U2 and Sylvester Stallone. Another nightclub is Palladium, located in the Escénica Avenue, the location gives the nightclub a view of the Santa Lucia Bay at night. Various DJs have had performances in Palladium among them DVBBS, Tom Swoon, Nervo and Junkie KID. Informal lobby or poolside cocktail bars often offer free live entertainment. In addition, there is the beach bar zone, where younger crowds go. These are located along the Costera road, face the ocean and feature techno or alternative rock. Most are concentrated between the Fiesta Americana and Continental Plaza hotels. These places tend to open earlier and have more informal dress. There is a bungee jump in this area as well.
Another attraction at Acapulco is the La Quebrada Cliff Divers. The tradition started in the 1930s when young men casually competed against each other to see who could dive from the highest point into the sea below. Eventually, locals began to ask for tips for those coming to see the men dive. Today the divers are professionals, diving from heights of into an inlet that is only wide and deep, after praying first at a shrine to the Virgin of Guadalupe. On the evening before December 12, the feast day of this Virgin, freestyle cliff divers jump into the sea to honor her. Dives range from the simple to the complicated and end with the "Ocean of Fire" when the sea is lit with gasoline, making a circle of flames which the diver aims for. The spectacle can be seen from a public area which charges a small fee or from the Hotel Plaza Las Glorias/El Mirador from its bar or restaurant terrace. There are a number of beaches in the Acapulco Bay and the immediate coastline. In the bay proper there are the La Angosta (in the Quebrada), Caleta, Caletilla, Dominguillo, Tlacopanocha, Hornos, Hornitos, Honda, Tamarindo, Condesa, Guitarrón, Icacos, Playuela, Playuelilla and Playa del Secreto. In the adjoining, smaller Bay of Puerto Marqués there is Pichilingue, Las Brisas, and Playa Roqueta. Facing open ocean just northwest of the bays is Pie de la Cuesta and southeast are Playa Revolcadero, Playa Aeromar, Playa Encantada and Barra Vieja. Two lagoons are in the area, Coyuca to the northwest of Acapulco Bay and Tres Palos to the southeast. Both lagoons have mangroves and offer boat tours. Tres Palos also has sea turtle nesting areas which are protected.
In addition to sunbathing, the beaches around the bay offer a number of services, such as boat rentals, boat tours, horseback riding, scuba diving and other aquatic sports. One popular cruise is from Caletilla Beach to Roqueta Island, which has places to snorkel, have lunch, and a lighthouse. There is also an underwater statue of the Virgin of Guadalupe here, created in 1958 by Armando Quesado in memory of a group of divers who died here. Many of the scuba-diving tours come to this area as well, where there are sunken ships, sea mountains, and cave rock formations. Another popular activity is deep-sea fishing. The major attraction is sail fishing. Fish caught here have weighed between 89 and 200 pounds. Sailfish are so plentiful that boat captains have been known to bet with a potential customer that if he does not catch anything, the trip is free.
The El Rollo Acapulco is a sea-life and aquatic park located on Costera Miguel Aleman. It offers wave pools, water slides and water toboggans. There are also dolphin shows daily and a swim with dolphins program. The center mostly caters to children. Another place that is popular with children is the "Parque Papagayo": a large family park which has a life-sized replica of a Spanish galleon, three artificial lakes, an aviary, a skating rink, rides, go-karts and more. The Dolores Olmedo House is located in the traditional downtown of Acapulco and is noted for the murals by Diego Rivera that adorn it. Olmedo and Rivera had been friend since Olmedo was a child and Rivera spent the last two years of his life here. During that time, he painted nearly nonstop and created the outside walls with tile mosaics, featuring Aztec deities such as Quetzalcoatl. The interior of the home is covered in murals. The home is not a museum, so only the outside murals can be seen by the public. There is a small museum called "Casa de la Máscara" (House of Masks) which is dedicated to masks, most of them from Mexico, but there are examples from many parts of the world. The collection contains about one thousand examples and is divided into seven rooms called Masks of the World, Mexico across History, The Huichols and the Jaguar, Alebrijes, Dances of Guerrero, Devils and Death, Identity and Fantasy, and Afro-Indian masks.
The Botanical Garden of Acapulco is a tropical garden located on lands owned by the Universidad Loyola del Pacífico. Most of the plants here are native to the region, and many, such as the Peltogyne mexicana or purple stick tree, are in danger of extinction. One cultural event that is held yearly in Acapulco is the "Festival Internacional de la Nao", which takes place in the Fort of San Diego, located near the Zócalo in downtown of the city. The Festival honors the remembrance of the city's interaction and trades with Oriental territories which started back in the Sixteenth Century. The Nao Festival consists of cultural activities with the support of organizations and embassies from India, China, Japan, Philippines, Thailand, Indonesia and South Korea. The variety of events go from film projections, musical interpretations and theatre to gastronomical classes, some of the events are specifically for kids. The annual French Festival takes place throughout Acapulco city and offers a multitude of events that cement cultural links between Mexico and France. The main features are a fashion show and a gourmet food fair. The Cinépolis Galerías Diana and the Teatro Juan Ruíz de Alarcón present French and French literary figures who give talks on their specialised subjects. Even some of the local nightclubs feature French DJs. Other festivals celebrated here include Carnival, the feast of San Isidro Labrador on 15 May, and in November, a crafts and livestock fair called the Nao de China.
There are a number of golf courses in Acapulco including the Acapulco Princess and the Pierre Marqués course, the latter designed by Robert Trent Jones in 1972 for the World Cup Golf Tournament. The Mayan Palace course was designed by Pedro Guericia and an economical course called the Club de Golf Acapulco is near the convention center. The most exclusive course is that of the Tres Vidas Golf Club, designed by Robert von Hagge. It is located next to the ocean and is home to flocks of ducks and other birds. Another famous sport tournament that has been held in Acapulco since 1993 is the Mexican Open tennis tournament, an ATP 500 event that currently takes place at the Arena GNP Seguros. Initially it was played in clay courts but it changed to hard court. The event has gained popularity within the passing of the years, attracting some of the top tennis players in the world including Novak Djokovic, Rafael Nadal and Marin Cilic. The total prize money is US$250,000.00 for WTA (women) and US$1,200,000.00 for ATP (men).
Acapulco also has a bullring, called the Plaza de Toros, near Caletilla Beach. The season runs during the winter and is called the Fiesta Brava. Spring break. Before 2010, over 100,000 American teenagers and young adults traveled to resort areas and balnearios throughout Mexico during spring break each year. The main reason students head to Mexico is the drinking age of 18 years (versus 21 for the United States), something that has been marketed by tour operators along with the sun and ocean. This has become attractive since the 1990s, especially since more traditional spring break places such as Daytona Beach, Florida, have enacted restrictions on drinking and other behaviors. This legislation has pushed spring break tourism to various parts of Mexico, with Acapulco as one of the top destinations. In the late 1990s and early 2000s, Cancún had been favored as the spring break destination of choice. However, Cancún has taken some steps to control the reckless behavior associated with the event, and students have been looking for someplace new. This led many more to choose Acapulco, in spite of the fact that for many travelers, the flight is longer and more expensive than to Cancún. Many were attracted by the glitzy hotels on the south side and Acapulco's famous nightlife. In 2008, 22,500 students came to Acapulco for spring break. Hotels did not get that many in 2009, due mostly to the economic situation in the United States, and partially because of scares of drug-related violence.
In February 2009, the US State Department issued a travel alert directed at college students planning spring break trips to Acapulco. The warning—a result of violent activity springing from Mexico's drug cartel débâcle—took college campuses by storm, with some schools going so far as to warn their students about the risks of travel to Mexico over spring break. Bill O'Reilly devoted a segment of his show, "The O'Reilly Factor", to urge students to stay away from Acapulco. In June 2009, a number of incidents occurred between the drug cartel and the government. These included coordinated attacks on police headquarters and open battles in the streets, involving large-caliber weapons and grenades. However, no incidents of violence against travelers on spring break were reported. Transportation. Nine passenger airlines, including four international ones, fly to Acapulco International Airport. In the city, there are many buses and taxi services one can take to get from place to place, but most of the locals choose to walk to their destinations. However, an important mode of transportation is the government-subsidized 'Colectivo' cab system. These cabs cost 13 pesos per person to ride, but they are not private. The driver will pick up more passengers as long as seats are available, and will transport them to their destination based on first-come, first-served rules. The colectivos each travel a designated area of the city, the three main ones being Costera, Colosio, Coloso, or a mixture of the three. Coloso cabs travel mainly to old Acapulco. Colosio cabs travel through most of the tourist area of Acapulco. Costera cabs drive up and down the coast of Acapulco, where most of the hotels for visitors are located, but which includes some of old Acapulco. Drivers have discretion over destinations; some are willing to travel to the other designated areas, especially during slow periods of the day.
The bus system is highly complex and can be rather confusing to an outsider. As far as transportation goes, it is the cheapest form, other than walking, in Acapulco. The most expensive buses have air conditioning, while the cheaper buses do not. For tourists, the Acapulco city government has established a system of yellow buses with Acapulco painted on the side of them. These buses are not for tourists only, but are certainly the nicest and most uniform of the bus systems. These buses travel the tourist section of Acapulco, driving up and down the coast. There are buses with specific routes and destinations, generally written on their windshields or shouted out by a barker riding in the front seat. Perhaps the most unusual thing about the privately operated buses is the fact that they are all highly decorated and personalized, with decals and home-made interior designs that range from comic book scenes, to pornography, and even to "Hello Kitty" themes. The bus network was simplified on 25 June 2016 with the implementation of the . The bus rapid transit system spans , with 16 stations spread throughout the city of Acapulco along five routes. Boarding is sped by pre- payment at stations.
UNESCO World Heritage Site nominations. In 2014, the idea to nominate the Manila-Acapulco Galleon Trade Route was initiated by the Mexican ambassador to UNESCO with the Filipino ambassador to UNESCO. An Experts' Roundtable Meeting was held at the University of Santo Tomas (UST) on April 23, 2015, as part of the preparation of the Philippines for the possible transnational nomination of the Manila-Acapulco Galleon Trade Route to the World Heritage List. The nomination will be made jointly with Mexico. The following are the experts and the topics they discussed during the roundtable meeting: Dr. Celestina Boncan on the Tornaviaje; Dr. Mary Jane A. Bolunia on Shipyards in the Bicol Region; Mr. Sheldon Clyde Jago-on, Bobby Orillaneda, and Ligaya Lacsina on Underwater Archaeology; Dr. Leovino Garcia on Maps and Cartography; Fr. Rene Javellana, S.J. on Fortifications in the Philippines; Felice Sta. Maria on Food; Dr. Fernando Zialcita on Textile; and Regalado Trota Jose on Historical Dimension. The papers presented and discussed during the roundtable meeting will be synthesized into a working document to establish the route's Outstanding Universal Value. The Mexican side reiterated that they will also follow suit with the preparations for the route's nomination. Spain has also backed the nomination of the Manila-Acapulco Trade Route in the UNESCO World Heritage Site list and has also suggested the Archives of the Manila-Acapulco Galleons to be nominated as part of a separate UNESCO list, the UNESCO Memory of the World Register.
Alan Kay Alan Curtis Kay (born May 17, 1940) is an American computer scientist who pioneered work on object-oriented programming and windowing graphical user interface (GUI) design. At Xerox PARC he led the design and development of the first modern windowed computer desktop interface. There he also led the development of the influential object-oriented programming language Smalltalk, both personally designing most of the early versions of the language and coining the term "object-oriented." He has been elected a Fellow of the American Academy of Arts and Sciences, the National Academy of Engineering, and the Royal Society of Arts. He received the Turing Award in 2003. Early life and work. In an interview on education in America with the Davis Group Ltd., Kay said: Originally from Springfield, Massachusetts, Kay's family relocated several times due to his father's career in physiology before ultimately settling in the New York metropolitan area. He attended Brooklyn Technical High School. Having accumulated enough credits to graduate, he then attended Bethany College in Bethany, West Virginia, where he majored in biology and minored in mathematics.
Kay then taught guitar in Denver, Colorado for a year. He was drafted in the United States Army, then qualified for officer training in the United States Air Force, where he became a computer programmer after passing an aptitude test. After his discharge, he enrolled at the University of Colorado Boulder and earned a Bachelor of Science (B.S.) in mathematics and molecular biology in 1966. In the autumn of 1966, he began graduate school at the University of Utah College of Engineering. He earned a Master of Science in electrical engineering in 1968, then a Doctor of Philosophy in computer science in 1969. His doctoral dissertation, "FLEX: A Flexible Extendable Language", described the invention of a computer language named FLEX. While there, he worked with "fathers of computer graphics" David C. Evans (who had recently been recruited from the University of California, Berkeley to start Utah's computer science department) and Ivan Sutherland (best known for writing such pioneering programs as Sketchpad). Kay credits Sutherland's 1963 thesis for influencing his views on objects and computer programming. As he grew busier with research for the Defense Advanced Research Projects Agency (DARPA), he ended his musical career.
In 1968, he met Seymour Papert and learned of the programming language Logo, a dialect of Lisp optimized for educational purposes. This led him to learn of the work of Jean Piaget, Jerome Bruner, Lev Vygotsky, and of constructionist learning, further influencing his professional orientation. On December 9 of that same year he was present in San Francisco for the Mother of all Demos, a landmark computer demonstration by Douglas Engelbart. Even though he was sick with a high fever on that day, the event was very influential in Kay's career. He recalled later: "It was one of the greatest experiences in my life". In 1969, Kay became a visiting researcher at the Stanford Artificial Intelligence Laboratory in anticipation of accepting a professorship at Carnegie Mellon University. Instead, in 1970, he joined the Xerox PARC research staff in Palo Alto, California. Through the decade, he developed prototypes of networked workstations using the programming language Smalltalk. Along with some colleagues at PARC, Kay is one of the fathers of the idea of object-oriented programming (OOP), which he named. Some original object-oriented concepts, including the use of the words 'object' and 'class', had been developed for Simula 67 at the Norwegian Computing Center. Kay said:
I'm sorry that I long ago coined the term "objects" for this topic because it gets many people to focus on the lesser idea. The big idea is "messaging". While at PARC, Kay conceived the Dynabook concept, a key progenitor of laptop and tablet computers and the e-book. He is also the architect of the modern overlapping windowing graphical user interface (GUI). Because the Dynabook was conceived as an educational platform, he is considered one of the first researchers into mobile learning; many features of the Dynabook concept have been adopted in the design of the One Laptop Per Child educational platform, with which Kay is actively involved. Subsequent work. From 1981 to 1984, Kay was Chief Scientist at Atari. In 1984, he became an Apple Fellow. After the closure of the Apple Advanced Technology Group in 1997, he was recruited by his friend Bran Ferren, head of research and development at Disney, to join Walt Disney Imagineering as a Disney Fellow. He remained there until Ferren left to start Applied Minds Inc with Imagineer Danny Hillis, leading to the cessation of the Fellows program.
In 2001, Kay founded Viewpoints Research Institute, a nonprofit organization dedicated to children, learning, and advanced software development. For their first ten years, Kay and his Viewpoints group were based at Applied Minds in Glendale, California, where he and Ferren worked on various projects. Kay served as president of the Institute until its closure in 2018. In 2002 Kay joined HP Labs as a senior fellow, departing when HP disbanded the Advanced Software Research Team on July 20, 2005. He has been an adjunct professor of computer science at the University of California, Los Angeles, a visiting professor at Kyoto University, and an adjunct professor at the Massachusetts Institute of Technology (MIT). Kay served on the advisory board of TTI/Vanguard. Squeak, Etoys, and Croquet. In December 1995, while still at Apple, Kay collaborated with many others to start the open source Squeak version of Smalltalk. As part of this effort, in November 1996, his team began research on what became the Etoys system. More recently he started, with David A. Smith, David P. Reed, Andreas Raab, Rick McGeer, Julian Lombardi, and Mark McCahill, the Croquet Project, an open-source networked 2D and 3D environment for collaborative work.
Tweak. In 2001, it became clear that the Etoy architecture in Squeak had reached its limits in what the Morphic interface infrastructure could do. Andreas Raab, a researcher in Kay's group then at Hewlett-Packard, proposed defining a "script process" and providing a default scheduling mechanism that avoided several more general problems. The result was a new user interface, proposed to replace the Squeak Morphic user interface. Tweak added mechanisms of islands, asynchronous messaging, players and costumes, language extensions, projects, and tile scripting. Its underlying object system is class-based, but to users (during programming) it acts as if it were prototype-based. Tweak objects are created and run in Tweak project windows. The Children's Machine. In November 2005, at the World Summit on the Information Society, the MIT research laboratories unveiled a new laptop computer for educational use around the world. It has many names, including the $100 Laptop, the One Laptop per Child program, the Children's Machine, and the XO-1. The program was founded and is sustained by Kay's friend Nicholas Negroponte, and is based on Kay's Dynabook ideal. Kay is a prominent co-developer of the computer, focusing on its educational software using Squeak and Etoys.
Reinventing programming. Kay has lectured extensively on the idea that the computer revolution is very new, and all of the good ideas have not been universally implemented. His lectures at the OOPSLA 1997 conference, and his ACM Turing Award talk, "The Computer Revolution Hasn't Happened Yet", were informed by his experiences with Sketchpad, Simula, Smalltalk, and the bloated code of commercial software. On August 31, 2006, Kay's proposal to the United States National Science Foundation (NSF) was granted, funding Viewpoints Research Institute for several years. The proposal title was "STEPS Toward the Reinvention of Programming: A compact and Practical Model of Personal Computing as a Self-exploratorium". STEPS is a recursive acronym that stands for "STEPS Toward Expressive Programming Systems". A sense of what Kay is trying to do comes from this quote, from the abstract of a seminar at Intel Research Labs, Berkeley: "The conglomeration of commercial and most open source software consumes in the neighborhood of several hundreds of millions of lines of code these days. We wonder: how small could be an understandable practical 'Model T' design that covers this functionality? 1M lines of code? 200K LOC? 100K LOC? 20K LOC?"
Personal life. Kay is a former professional jazz guitarist, composer, and theatrical designer. He also is an amateur classical pipe organist. Awards and honors. Kay has received many awards and honors, including: His other honors include the J-D Warnier Prix d'Informatique, the ACM Systems Software Award, the NEC Computers & Communication Foundation Prize, the Funai Foundation Prize, the Lewis Branscomb Technology Award, and the ACM SIGCSE Award for Outstanding Contributions to Computer Science Education.
APL (programming language) APL (named after the book "A Programming Language") is a programming language developed in the 1960s by Kenneth E. Iverson. Its central datatype is the multidimensional array. It uses a large range of special graphic symbols to represent most functions and operators, leading to very concise code. It has been an important influence on the development of concept modeling, spreadsheets, functional programming, and computer math packages. It has also inspired several other programming languages. History. Mathematical notation. A mathematical notation for manipulating arrays was developed by Kenneth E. Iverson, starting in 1957 at Harvard University. In 1960, he began work for IBM where he developed this notation with Adin Falkoff and published it in his book "A Programming Language" in 1962. The preface states its premise: This notation was used inside IBM for short research reports on computer systems, such as the Burroughs B5000 and its stack mechanism when stack machines versus register machines were being evaluated by IBM for upcoming computers.
Iverson also used his notation in a draft of the chapter "A Programming Language", written for a book he was writing with Fred Brooks, "Automatic Data Processing", which would be published in 1963. In 1979, Iverson received the Turing Award for his work on APL. Development into a computer programming language. As early as 1962, the first attempt to use the notation to describe a complete computer system happened after Falkoff discussed with William C. Carter his work to standardize the instruction set for the machines that later became the IBM System/360 family. In 1963, Herbert Hellerman, working at the IBM Systems Research Institute, implemented a part of the notation on an IBM 1620 computer, and it was used by students in a special high school course on calculating transcendental functions by series summation. Students tested their code in Hellerman's lab. This implementation of a part of the notation was called Personalized Array Translator (PAT). In 1963, Falkoff, Iverson, and Edward H. Sussenguth Jr., all working at IBM, used the notation for a formal description of the IBM System/360 series machine architecture and functionality, which resulted in a paper published in "IBM Systems Journal" in 1964. After this was published, the team turned their attention to an implementation of the notation on a computer system. One of the motivations for this focus of implementation was the interest of John L. Lawrence who had new duties with Science Research Associates, an educational company bought by IBM in 1964. Lawrence asked Iverson and his group to help use the language as a tool to develop and use computers in education.
After Lawrence M. Breed and Philip S. Abrams of Stanford University joined the team at IBM Research, they continued their prior work on an implementation programmed in FORTRAN IV for a part of the notation which had been done for the IBM 7090 computer running on the IBSYS operating system. This work was finished in late 1965 and later named IVSYS (for Iverson system). The basis of this implementation was described in detail by Abrams in a Stanford University Technical Report, "An Interpreter for Iverson Notation" in 1966. The academic aspect of this was formally supervised by Niklaus Wirth. Like Hellerman's PAT system earlier, this implementation omitted the APL character set, but used special English reserved words for functions and operators. The system was later adapted for a time-sharing system and, by November 1966, it had been reprogrammed for the IBM System/360 Model 50 computer running in a time-sharing mode and was used internally at IBM. Hardware. A key development in the ability to use APL effectively, before the wide use of cathode-ray tube (CRT) terminals, was the development of a special IBM Selectric typewriter interchangeable typing element with all the special APL characters on it. This was used on paper printing terminal workstations using the Selectric typewriter and typing element mechanism, such as the IBM 1050 and IBM 2741 terminal. Keycaps could be placed over the normal keys to show which APL characters would be entered and typed when that key was struck. For the first time, a programmer could type in and see proper APL characters as used in Iverson's notation and not be forced to use awkward English keyword representations of them. Falkoff and Iverson had the special APL Selectric typing elements, 987 and 988, designed in late 1964, although no APL computer system was available to use them. Iverson cited Falkoff as the inspiration for the idea of using an IBM Selectric typing element for the APL character set.
Many APL symbols, even with the APL characters on the Selectric typing element, still had to be typed in by over-striking two extant element characters. An example is the "grade up" character, which had to be made from a "delta" (shift-H) and a "Sheffer stroke" (shift-M). This was necessary because the APL character set was much larger than the 88 characters allowed on the typing element, even when letters were restricted to upper-case (capitals). Commercial availability. The first APL interactive login and creation of an APL workspace was in 1966 by Larry Breed using an IBM 1050 terminal at the IBM Mohansic Labs near Thomas J. Watson Research Center, the home of APL, in Yorktown Heights, New York. IBM was chiefly responsible for introducing APL to the marketplace. The first publicly available version of APL was released in 1968 for the IBM 1130. IBM provided "APL\1130" for free but without liability or support. It would run in as little as 8k 16-bit words of memory, and used a dedicated 1 megabyte hard disk.
APL gained its foothold on mainframe timesharing systems from the late 1960s through the early 1980s, in part because it would support multiple users on lower-specification systems that had no dynamic address translation hardware. Additional improvements in performance for selected IBM System/370 mainframe systems included the "APL Assist Microcode" in which some support for APL execution was included in the processor's firmware, as distinct from being implemented entirely by higher-level software. Somewhat later, as suitably performing hardware was finally growing available in the mid- to late-1980s, many users migrated their applications to the personal computer environment. Early IBM APL interpreters for IBM 360 and IBM 370 hardware implemented their own multi-user management instead of relying on the host services, thus they were their own timesharing systems. First introduced for use at IBM in 1966, the "APL\360" system was a multi-user interpreter. The ability to programmatically communicate with the operating system for information and setting interpreter system variables was done through special privileged "I-beam" functions, using both monadic and dyadic operations.
In 1973, IBM released "APL.SV", which was a continuation of the same product, but which offered shared variables as a means to access facilities outside of the APL system, such as operating system files. In the mid-1970s, the IBM mainframe interpreter was even adapted for use on the IBM 5100 desktop computer, which had a small CRT and an APL keyboard, when most other small computers of the time only offered BASIC. In the 1980s, the "VSAPL" program product enjoyed wide use with Conversational Monitor System (CMS), Time Sharing Option (TSO), VSPC, MUSIC/SP, and CICS users. In 1973–1974, Patrick E. Hagerty directed the implementation of the University of Maryland APL interpreter for the 1100 line of the Sperry UNIVAC 1100/2200 series mainframe computers. In 1974, student Alan Stebbens was assigned the task of implementing an internal function. Xerox APL was available from June 1975 for Xerox 560 and Sigma 6, 7, and 9 mainframes running CP-V and for Honeywell CP-6. In the 1960s and 1970s, several timesharing firms arose that sold APL services using modified versions of the IBM APL\360 interpreter. In North America, the better-known ones were IP Sharp Associates, Scientific Time Sharing Corporation (STSC), Time Sharing Resources (TSR), and The Computer Company (TCC). CompuServe also entered the market in 1978 with an APL Interpreter based on a modified version of Digital Equipment Corp and Carnegie Mellon's, which ran on DEC's KI and KL 36-bit machines. CompuServe's APL was available both to its commercial market and the consumer information service. With the advent first of less expensive mainframes such as the IBM 4300, and later the personal computer, by the mid-1980s, the timesharing industry was all but gone.
"Sharp APL" was available from IP Sharp Associates, first as a timesharing service in the 1960s, and later as a program product starting around 1979. "Sharp APL" was an advanced APL implementation with many language extensions, such as "packages" (the ability to put one or more objects into a single variable), a file system, nested arrays, and shared variables. APL interpreters were available from other mainframe and mini-computer manufacturers also, notably Burroughs, Control Data Corporation (CDC), Data General, Digital Equipment Corporation (DEC), Harris, Hewlett-Packard (HP), Siemens, Xerox and others. Garth Foster of Syracuse University sponsored regular meetings of the APL implementers' community at Syracuse's Minnowbrook Conference Center in Blue Mountain Lake, New York. In later years, Eugene McDonnell organized similar meetings at the Asilomar Conference Grounds near Monterey, California, and at Pajaro Dunes near Watsonville, California. The SIGAPL special interest group of the Association for Computing Machinery continues to support the APL community.
Microcomputers. On microcomputers, which became available from the mid-1970s onwards, BASIC became the dominant programming language. Nevertheless, some microcomputers provided APL instead – the first being the Intel 8008-based MCM/70 which was released in 1974 and which was primarily used in education. Another machine of this time was the VideoBrain Family Computer, released in 1977, which was supplied with its dialect of APL called APL/S. The Commodore SuperPET, introduced in 1981, included an APL interpreter developed by the University of Waterloo. In 1976, Bill Gates claimed in his Open Letter to Hobbyists that Microsoft Corporation was implementing APL for the Intel 8080 and Motorola 6800 but had "very little incentive to make [it] available to hobbyists" because of software piracy. It was never released. APL2. Starting in the early 1980s, IBM APL development, under the leadership of Jim Brown, implemented a new version of the APL language that contained as its primary enhancement the concept of "nested arrays", where an array can contain other arrays, and new language features which facilitated integrating nested arrays into program workflow. Ken Iverson, no longer in control of the development of the APL language, left IBM and joined I. P. Sharp Associates, where one of his major contributions was directing the evolution of Sharp APL to be more in accord with his vision. APL2 was first released for CMS and TSO in 1984. The APL2 Workstation edition (Windows, OS/2, AIX, Linux, and Solaris) followed later.
As other vendors were busy developing APL interpreters for new hardware, notably Unix-based microcomputers, APL2 was almost always the standard chosen for new APL interpreter developments. Even today, most APL vendors or their users cite APL2 compatibility as a selling point for those products. IBM cites its use for problem solving, system design, prototyping, engineering and scientific computations, expert systems, for teaching mathematics and other subjects, visualization and database access. Modern implementations. Various implementations of APL by APLX, Dyalog, et al., include extensions for object-oriented programming, support for .NET, XML-array conversion primitives, graphing, operating system interfaces, and lambda calculus expressions. Freeware versions include GNU APL for Linux and NARS2000 for Windows (which also runs on Linux under Wine). Both of these are fairly complete versions of APL2 with various language extensions. Derivative languages. APL has formed the basis of, or influenced, the following languages:
Language characteristics. Character set. APL has been criticized and praised for its choice of a unique character set. In the 1960s and 1970s, few terminal devices or even displays could reproduce the APL character set. The most popular ones employed the IBM Selectric print mechanism used with a special APL type element. One of the early APL line terminals (line-mode operation only, "not" full screen) was the Texas Instruments TI Model 745 () with the full APL character set which featured half and full duplex telecommunications modes, for interacting with an APL time-sharing service or remote mainframe to run a remote computer job, remote job entry (RJE). Over time, with the universal use of high-quality graphic displays, printing devices and Unicode support, the APL character font problem has largely been eliminated. However, entering APL characters requires the use of input method editors, keyboard mappings, virtual/on-screen APL symbol sets, or easy-reference printed keyboard cards which can frustrate beginners accustomed to other programming languages. With beginners who have no prior experience with other programming languages, a study involving high school students found that typing and using APL characters did not hinder the students in any measurable way.
In defense of APL, it requires fewer characters to type, and keyboard mappings become memorized over time. Special APL keyboards are also made and in use today, as are freely downloadable fonts for operating systems such as Microsoft Windows. The reported productivity gains assume that one spends enough time working in the language to make it worthwhile to memorize the symbols, their semantics, keyboard mappings, and many idioms for common tasks. Design. Unlike traditionally structured programming languages, APL code is typically structured as chains of monadic or dyadic functions, and operators acting on arrays. APL has many nonstandard "primitives" (functions and operators) that are indicated by a single symbol or a combination of a few symbols. All primitives are defined to have the same precedence, and always associate to the right. Thus, APL is "read" or best understood from right-to-left. Early APL implementations ( or so) had no programming loop control flow structures, such as codice_1 or codice_2 loops, and codice_3 constructs. Instead, they used array operations, and use of structured programming constructs was often unneeded, since an operation could be performed on a full array in one statement. For example, the codice_4 function (codice_5) can replace for-loop iteration: ιN when applied to a scalar positive integer yields a one-dimensional array (vector), 1 2 3 ... N. Later APL implementations generally include comprehensive control structures, so that data structure and program control flow can be clearly and cleanly separated.
The APL environment is called a "workspace". In a workspace the user can define programs and data, i.e., the data values exist also outside the programs, and the user can also manipulate the data without having to define a program. In the examples below, the APL interpreter first types six spaces before awaiting the user's input. Its own output starts in column one. The user can save the workspace with all values, programs, and execution status. APL uses a set of non-ASCII symbols, which are an extension of traditional arithmetic and algebraic notation. Having single character names for single instruction, multiple data (SIMD) vector functions is one way that APL enables compact formulation of algorithms for data transformation such as computing Conway's Game of Life in one line of code. In nearly all versions of APL, it is theoretically possible to express any computable function in one expression, that is, in one line of code. Due to the unusual character set, many programmers use special keyboards with APL keytops to write APL code. Although there are various ways to write APL code using only ASCII characters, in practice it is almost never done. (This may be thought to support Iverson's thesis about notation as a tool of thought.) Most if not all modern implementations use standard keyboard layouts, with special mappings or input method editors to access non-ASCII characters. Historically, the APL font has been distinctive, with uppercase italic alphabetic characters and upright numerals and symbols. Most vendors continue to display the APL character set in a custom font.
Advocates of APL claim that the examples of so-called "write-only code" (badly written and almost incomprehensible code) are almost invariably examples of poor programming practice or novice mistakes, which can occur in any language. Advocates also claim that they are far more productive with APL than with more conventional computer languages, and that working software can be implemented in far less time and with far fewer programmers than using other technology. They also may claim that because it is compact and terse, APL lends itself well to larger-scale software development and complexity, because the number of lines of code can be reduced greatly. Many APL advocates and practitioners also view standard programming languages such as COBOL and Java as being comparatively tedious. APL is often found where time-to-market is important, such as with trading systems. Terminology. APL makes a clear distinction between "functions" and "operators". Functions take arrays (variables or constants or expressions) as arguments, and return arrays as results. Operators (similar to higher-order functions) take functions or arrays as arguments, and derive related functions. For example, the "sum" function is derived by applying the "reduction" operator to the "addition" function. Applying the same reduction operator to the "maximum" function (which returns the larger of two numbers) derives a function which returns the largest of a group (vector) of numbers. In the J language, Iverson substituted the terms "verb" for "function" and "adverb" or "conjunction" for "operator".
APL also identifies those features built into the language, and represented by a symbol, or a fixed combination of symbols, as "primitives". Most primitives are either functions or operators. Coding APL is largely a process of writing non-primitive functions and (in some versions of APL) operators. However a few primitives are considered to be neither functions nor operators, most noticeably assignment. Some words used in APL literature have meanings that differ from those in both mathematics and the generality of computer science. Syntax. APL has explicit representations of functions, operators, and syntax, thus providing a basis for the clear and explicit statement of extended facilities in the language, and tools to experiment on them. Examples. Hello, world. This displays "Hello, world": 'Hello, world' A design theme in APL is to define default actions in some cases that would produce syntax errors in most other programming languages. The 'Hello, world' string constant above displays, because display is the default action on any expression for which no action is specified explicitly (e.g. assignment, function parameter).
Exponentiation. Another example of this theme is that exponentiation in APL is written as , which indicates raising 2 to the power 3 (this would be written as or in some languages, or relegated to a function call such as in others). Many languages use to signify multiplication, as in , but APL chooses to use . However, if no base is specified (as with the statement in APL, or in other languages), most programming languages one would see this as a syntax error. APL, however, assumes the missing base to be the natural logarithm constant e, and interprets as . Simple statistics. Suppose that is an array of numbers. Then gives its average. Reading "right-to-left", gives the number of elements in X, and since is a dyadic operator, the term to its left is required as well. It is surrounded by parentheses since otherwise X would be taken (so that the summation would be of —each element of X divided by the number of elements in X), and gives the sum of the elements of X. Building on this, the following expression computes standard deviation:
Naturally, one would define this expression as a function for repeated use rather than rewriting it each time. Further, since assignment is an operator, it can appear within an expression, so the following would place suitable values into T, AV and SD: "Pick 6" lottery numbers. This following immediate-mode expression generates a typical set of "Pick 6" lottery numbers: six pseudo-random integers ranging from 1 to 40, "guaranteed non-repeating", and displays them sorted in ascending order: x[⍋x←6?40] The above does a lot, concisely, although it may seem complex to a new APLer. It combines the following APL "functions" (also called "primitives" and "glyphs"): Since there is no function to the left of the left-most x to tell APL what to do with the result, it simply outputs it to the display (on a single line, separated by spaces) without needing any explicit instruction to do that. codice_6 also has a monadic equivalent called codice_15, which simply returns one random integer between 1 and its sole operand [to the right of it], inclusive. Thus, a role-playing game program might use the expression codice_16 to roll a twenty-sided die.
Prime numbers. The following expression finds all prime numbers from 1 to R. In both time and space, the calculation complexity is formula_1 (in Big O notation). (~R∊R∘.×R)/R←1↓⍳R Executed from right to left, this means: Sorting. The following expression sorts a word list stored in matrix X according to word length: X[⍋X+.≠' ';] Game of Life. The following function "life", written in Dyalog APL, takes a Boolean matrix and calculates the new generation according to Conway's Game of Life. It demonstrates the power of APL to implement a complex algorithm in very little code, but understanding it requires some advanced knowledge of APL (as the same program would in many languages). HTML tags removal. In the following example, also Dyalog, the first line assigns some HTML code to a variable codice_47 and then uses an APL expression to remove all the HTML tags: txt←'<html><body><p>This is <em>emphasized</em> text.</p></body></html>' {⍵ /⍨ ~{⍵∨≠\⍵}⍵∊'<>'} txt This is emphasized text.
Naming. APL derives its name from the initials of Iverson's book "A Programming Language", even though the book describes Iverson's mathematical notation, rather than the implemented programming language described in this article. The name is used only for actual implementations, starting with APL\360. Adin Falkoff coined the name in 1966 during the implementation of APL\360 at IBM: "APL" is occasionally re-interpreted as "Array Programming Language" or "Array Processing Language", thereby making "APL" into a backronym. Logo. There has always been cooperation between APL vendors, and joint conferences were held on a regular basis from 1969 until 2010. At such conferences, APL merchandise was often handed out, featuring APL motifs or collection of vendor logos. Common were apples (as a pun on the similarity in pronunciation of "apple" and "APL") and the code snippet which are the symbols produced by the classic APL keyboard layout when holding the APL modifier key and typing "APL". Despite all these community efforts, no universal vendor-agnostic logo for the programming language emerged. As popular programming languages increasingly have established recognisable logos, Fortran getting one in 2020, British APL Association launched a campaign in the second half of 2021, to establish such a logo for APL, and after a community election and multiple rounds of feedback, a logo was chosen in May 2022.
Use. APL is used for many purposes including financial and insurance applications, artificial intelligence, neural networks and robotics. It has been argued that APL is a calculation tool and not a programming language; its symbolic nature and array capabilities have made it popular with domain experts and data scientists who do not have or require the skills of a computer programmer. APL is well suited to image manipulation and computer animation, where graphic transformations can be encoded as matrix multiplications. One of the first commercial computer graphics houses, Digital Effects, produced an APL graphics product named "Visions", which was used to create television commercials and animation for the 1982 film "Tron". Latterly, the Stormwind boating simulator uses APL to implement its core logic, its interfacing to the rendering pipeline middleware and a major part of its physics engine. Today, APL remains in use in a wide range of commercial and scientific applications, for example investment management,
asset management, health care, and DNA profiling. Notable implementations. APL\360. The first implementation of APL using recognizable APL symbols was APL\360 which ran on the IBM System/360, and was completed in November 1966 though at that time remained in use only within IBM. In 1973 its implementors, Larry Breed, Dick Lathwell and Roger Moore, were awarded the Grace Murray Hopper Award from the Association for Computing Machinery (ACM). It was given "for their work in the design and implementation of APL\360, setting new standards in simplicity, efficiency, reliability and response time for interactive systems." In 1975, the IBM 5100 microcomputer offered APL\360 as one of two built-in ROM-based interpreted languages for the computer, complete with a keyboard and display that supported all the special symbols used in the language. Significant developments to APL\360 included CMS/APL, which made use of the virtual storage capabilities of CMS and APLSV, which introduced shared variables, system variables and system functions. It was subsequently ported to the IBM System/370 and VSPC platforms until its final release in 1983, after which it was replaced by APL2.
APL\1130. In 1968, APL\1130 became the first publicly available APL system, created by IBM for the IBM 1130. It became the most popular IBM Type-III Library software that IBM released. APL*Plus and Sharp APL. APL*Plus and Sharp APL are versions of APL\360 with added business-oriented extensions such as data formatting and facilities to store APL arrays in external files. They were jointly developed by two companies, employing various members of the original IBM APL\360 development team. The two companies were I. P. Sharp Associates (IPSA), an APL\360 services company formed in 1964 by Ian Sharp, Roger Moore and others, and STSC, a time-sharing and consulting service company formed in 1969 by Lawrence Breed and others. Together the two developed APL*Plus and thereafter continued to work together but develop APL separately as APL*Plus and Sharp APL. STSC ported APL*Plus to many platforms with versions being made for the VAX 11, PC and UNIX, whereas IPSA took a different approach to the arrival of the personal computer and made Sharp APL available on this platform using additional PC-XT/360 hardware. In 1993, Soliton Incorporated was formed to support Sharp APL and it developed Sharp APL into SAX (Sharp APL for Unix). , APL*Plus continues as APL2000 APL+Win.
In 1985, Ian Sharp, and Dan Dyer of STSC, jointly received the Kenneth E. Iverson Award for Outstanding Contribution to APL. APL2. APL2 was a significant re-implementation of APL by IBM which was developed from 1971 and first released in 1984. It provides many additions to the language, of which the most notable is nested (non-rectangular) array support. The entire APL2 Products and Services Team was awarded the Iverson Award in 2007. In 2021, IBM sold APL2 to Log-On Software, who develop and sell the product as "Log-On APL2". APLGOL. In 1972, APLGOL was released as an experimental version of APL that added structured programming language constructs to the language framework. New statements were added for interstatement control, conditional statement execution, and statement structuring, as well as statements to clarify the intent of the algorithm. It was implemented for Hewlett-Packard in 1977. Dyalog APL. Dyalog APL was first released by British company Dyalog Ltd. in 1983 and, , is available for AIX, Linux (including on the Raspberry Pi), macOS and Microsoft Windows platforms. It is based on APL2, with extensions to support object-oriented programming, functional programming, and tacit programming. Licences are free for personal/non-commercial use.
In 1995, two of the development team – John Scholes and Peter Donnelly – were awarded the Iverson Award for their work on the interpreter. Gitte Christensen and Morten Kromberg were joint recipients of the Iverson Award in 2016. NARS2000. NARS2000 is an open-source APL interpreter written by Bob Smith, a prominent APL developer and implementor from STSC in the 1970s and 1980s. NARS2000 contains advanced features and new datatypes and runs natively on Microsoft Windows, and other platforms under Wine. It is named after a development tool from the 1980s, NARS (Nested Arrays Research System). APLX. APLX is a cross-platform dialect of APL, based on APL2 and with several extensions, which was first released by British company MicroAPL in 2002. Although no longer in development or on commercial sale it is now available free of charge from Dyalog. York APL. York APL was developed at the York University, Ontario around 1968, running on IBM 360 mainframes. One notable difference between it and APL\360 was that it defined the "shape" (ρ) of a scalar as 1 whereas APL\360 defined it as the more mathematically correct 0 — this made it easier to write functions that acted the same with scalars and vectors.
GNU APL. GNU APL is a free implementation of Extended APL as specified in ISO/IEC 13751:2001 and is thus an implementation of APL2. It runs on Linux, macOS, several BSD dialects, and on Windows (either using Cygwin for full support of all its system functions or as a native 64-bit Windows binary with some of its system functions missing). GNU APL uses Unicode internally and can be scripted. It was written by Jürgen Sauermann. Richard Stallman, founder of the GNU Project, was an early adopter of APL, using it to write a text editor as a high school student in the summer of 1969. Interpretation and compilation of APL. APL is traditionally an interpreted language, having language characteristics such as weak variable typing not well suited to compilation. However, with arrays as its core data structure it provides opportunities for performance gains through parallelism, parallel computing, massively parallel applications, and very-large-scale integration (VLSI), and from the outset APL has been regarded as a high-performance language – for example, it was noted for the speed with which it could perform complicated matrix operations "because it operates on arrays and performs operations like matrix inversion internally".
Nevertheless, APL is rarely purely interpreted and compilation or partial compilation techniques that are, or have been, used include the following: Idiom recognition. Most APL interpreters support idiom recognition and evaluate common idioms as single operations. For example, by evaluating the idiom codice_48 as a single operation (where codice_49 is a Boolean vector and codice_50 is an array), the creation of two intermediate arrays is avoided. Optimised bytecode. Weak typing in APL means that a name may reference an array (of any datatype), a function or an operator. In general, the interpreter cannot know in advance which form it will be and must therefore perform analysis, syntax checking etc. at run-time. However, in certain circumstances, it is possible to deduce in advance what type a name is expected to reference and then generate bytecode which can be executed with reduced run-time overhead. This bytecode can also be optimised using compilation techniques such as constant folding or common subexpression elimination. The interpreter will execute the bytecode when present and when any assumptions which have been made are met. Dyalog APL includes support for optimised bytecode.
Compilation. Compilation of APL has been the subject of research and experiment since the language first became available; the first compiler is considered to be the Burroughs APL-700 which was released around 1971. In order to be able to compile APL, language limitations have to be imposed. APEX is a research APL compiler which was written by Robert Bernecky and is available under the GNU General Public License. The STSC APL Compiler is a hybrid of a bytecode optimiser and a compiler – it enables compilation of functions to machine code provided that its sub-functions and globals are declared, but the interpreter is still used as a runtime library and to execute functions which do not meet the compilation requirements. Standards. APL has been standardized by the American National Standards Institute (ANSI) working group X3J10 and International Organization for Standardization (ISO) and International Electrotechnical Commission (IEC), ISO/IEC Joint Technical Committee 1 Subcommittee 22 Working Group 3. The Core APL language is specified in ISO 8485:1989, and the Extended APL language is specified in ISO/IEC 13751:2001.
ALGOL ALGOL (; short for "Algorithmic Language") is a family of imperative computer programming languages originally developed in 1958. ALGOL heavily influenced many other languages and was the standard method for algorithm description used by the Association for Computing Machinery (ACM) in textbooks and academic sources for more than thirty years. In the sense that the syntax of most modern languages is "Algol-like", it was arguably more influential than three other high-level programming languages among which it was roughly contemporary: FORTRAN, Lisp, and COBOL. It was designed to avoid some of the perceived problems with FORTRAN and eventually gave rise to many other programming languages, including PL/I, Simula, BCPL, B, Pascal, Ada, and C. ALGOL introduced code blocks and the codice_1...codice_2 pairs for delimiting them. It was also the first language implementing nested function definitions with lexical scope. Moreover, it was the first programming language which gave detailed attention to formal language definition and through the "Algol 60 Report" introduced Backus–Naur form, a principal formal grammar notation for language design.
There were three major specifications, named after the years they were first published: ALGOL 68 is substantially different from ALGOL 60 and was not well received, so reference to "Algol" is generally understood to mean ALGOL 60 and its dialects. History. ALGOL was developed jointly by a committee of European and American computer scientists in a meeting in 1958 at the Swiss Federal Institute of Technology in Zurich (cf. ALGOL 58). It specified three different syntaxes: a reference syntax, a publication syntax, and an implementation syntax, syntaxes that permitted it to use different keyword names and conventions for decimal points (commas vs periods) for different languages. ALGOL was used mostly by research computer scientists in the United States and in Europe; commercial applications were hindered by the absence of standard input/output facilities in its description, and the lack of interest in the language by large computer vendors (other than Burroughs Corporation). ALGOL 60 did however become the standard for the publication of algorithms and had a profound effect on future language development.
John Backus developed the "Backus normal form" method of describing programming languages specifically for ALGOL 58. It was revised and expanded by Peter Naur for ALGOL 60, and at Donald Knuth's suggestion renamed Backus–Naur form. Peter Naur: "As editor of the ALGOL Bulletin I was drawn into the international discussions of the language and was selected to be member of the European language design group in November 1959. In this capacity I was the editor of the ALGOL 60 report, produced as the result of the ALGOL 60 meeting in Paris in January 1960." The following people attended the meeting in Paris (from 11 to 16 January): Alan Perlis gave a vivid description of the meeting: "The meetings were exhausting, interminable, and exhilarating. One became aggravated when one's good ideas were discarded along with the bad ones of others. Nevertheless, diligence persisted during the entire period. The chemistry of the 13 was excellent." Legacy. A significant contribution of the ALGOL 58 Report was to provide standard terms for programming concepts: statement, declaration, type, label, primary, block, and others.
ALGOL 60 inspired many languages that followed it. Tony Hoare remarked: "Here is a language so far ahead of its time that it was not only an improvement on its predecessors but also on nearly all its successors." The Scheme programming language, a variant of Lisp that adopted the block structure and lexical scope of ALGOL, also adopted the wording "Revised Report on the Algorithmic Language Scheme" for its standards documents in homage to ALGOL. Properties. ALGOL 60 as officially defined had no I/O facilities; implementations defined their own in ways that were rarely compatible with each other. In contrast, ALGOL 68 offered an extensive library of "transput" (input/output) facilities. ALGOL 60 allowed for two evaluation strategies for parameter passing: the common call-by-value, and call-by-name. Call-by-name has certain effects in contrast to call-by-reference. For example, without specifying the parameters as "value" or "reference", it is impossible to develop a procedure that will swap the values of two parameters if the actual parameters that are passed in are an integer variable and an array that is indexed by that same integer variable. Think of passing a pointer to swap(i, A[i]) in to a function. Now that every time swap is referenced, it is reevaluated. Say i := 1 and A[i] := 2, so every time swap is referenced it will return the other combination of the values ([1,2], [2,1], [1,2] and so on). A similar situation occurs with a random function passed as actual argument.
Call-by-name is known by many compiler designers for the interesting "thunks" that are used to implement it. Donald Knuth devised the "man or boy test" to separate compilers that correctly implemented "recursion and non-local references." This test contains an example of call-by-name. ALGOL 68 was defined using a two-level grammar formalism invented by Adriaan van Wijngaarden and which bears his name. Van Wijngaarden grammars use a context-free grammar to generate an infinite set of productions that will recognize a particular ALGOL 68 program; notably, they are able to express the kind of requirements that in many other programming language standards are labelled "semantics" and have to be expressed in ambiguity-prone natural language prose, and then implemented in compilers as "ad hoc" code attached to the formal language parser. Examples and portability. Code sample comparisons. ALGOL 60. procedure Absmax(a) Size:(n, m) Result:(y) Subscripts:(i, k); value n, m; array a; integer n, m, i, k; real y; comment The absolute greatest element of the matrix a, of size n by m,
is copied to y, and the subscripts of this element to i and k; begin integer p, q; y := 0; i := k := 1; for p := 1 step 1 until n do for q := 1 step 1 until m do if abs(a[p, q]) > y then begin y := abs(a[p, q]); i := p; k := q end end Absmax Here is an example of how to produce a table using Elliott 803 ALGOL. FLOATING POINT ALGOL TEST' BEGIN REAL A,B,C,D' READ D' FOR A:= 0.0 STEP D UNTIL 6.3 DO BEGIN PRINT ,££L??' B := SIN(A)' C := COS(A)' PRINT PUNCH(3),,A,B,C' END END' ALGOL 68. The following code samples are ALGOL 68 versions of the above ALGOL 60 code samples. ALGOL 68 implementations used ALGOL 60's approaches to stropping. In ALGOL 68's case tokens with the bold typeface are reserved words, types (modes) or operators. proc abs max = ([,]real a, ref real y, ref int i, k)real: comment The absolute greatest element of the matrix a, of size ⌈a by 2⌈a is transferred to y, and the subscripts of this element to i and k; comment begin real y := 0; i := ⌊a; k := 2⌊a; for p from ⌊a to ⌈a do
for q from 2⌊a to 2⌈a do if abs a[p, q] > y then y := abs a[p, q]; i := p; k := q fi od od; y end # abs max # Note: lower (⌊) and upper (⌈) bounds of an array, and array slicing, are directly available to the programmer. floating point algol68 test: real a,b,c,d; # "printf" – sends output to the file "stand out". # # "printf($p$);" – selects a "new page" # printf(($pg$,"Enter d:")); read(d); for step from 0 while a:=step*d; a <= 2*pi do printf($l$); # "$l$" - selects a "new line". # b := sin(a); c := cos(a); printf(($z-d.6d$,a,b,c)) # formats output with 1 digit before and 6 after the decimal point. # od Timeline: Hello world. The variations and lack of portability of the programs from one implementation to another is easily demonstrated by the classic hello world program. ALGOL 58 (IAL). ALGOL 58 had no I/O facilities. ALGOL 60 family. Since ALGOL 60 had no I/O facilities, there is no portable hello world program in ALGOL. The next three examples are in Burroughs Extended Algol. The first two direct output at the interactive terminal they are run on. The first uses a character array, similar to C. The language allows the array identifier to be used as a pointer to the array, and hence in a REPLACE statement.
A simpler program using an inline format: An even simpler program using the Display statement. Note that its output would end up at the system console ('SPO'): An alternative example, using Elliott Algol I/O is as follows. Elliott Algol used different characters for "open-string-quote" and "close-string-quote", represented here by and . Below is a version from Elliott 803 Algol (A104). The standard Elliott 803 used five-hole paper tape and thus only had upper case. The code lacked any quote characters so £ (UK Pound Sign) was used for open quote and ? (Question Mark) for close quote. Special sequences were placed in double quotes (e.g£. £L?? produced a new line on the teleprinter). HIFOLKS' BEGIN PRINT £HELLO WORLD£L??' END' The ICT 1900 series Algol I/O version allowed input from paper tape or punched card. Paper tape 'full' mode allowed lower case. Output was to a line printer. The open and close quote characters were represented using '(' and ')' and spaces by %. 'BEGIN' WRITE TEXT('('HELLO%WORLD')');
'END' ALGOL 68. ALGOL 68 code was published with reserved words typically in lowercase, but bolded or underlined. begin printf(($gl$,"Hello, world!")) end In the language of the "Algol 68 Report" the input/output facilities were collectively called the "Transput". Timeline of ALGOL special characters. The ALGOLs were conceived at a time when character sets were diverse and evolving rapidly; also, the ALGOLs were defined so that only "uppercase" letters were required. 1960: IFIP – The Algol 60 language and report included several mathematical symbols which are available on modern computers and operating systems, but, unfortunately, were unsupported on most computing systems at the time. For instance: ×, ÷, ≤, ≥, ≠, ¬, ∨, ∧, ⊂, ≡, ␣ and ⏨. 1961 September: ASCII – The ASCII character set, then in an early stage of development, had the \ (Back slash) character added to it in order to support ALGOL's Boolean operators /\ and \/. 1962: ALCOR – This character set included the unusual "᛭" runic cross character for multiplication and the "⏨" Decimal Exponent Symbol for floating point notation. 1964: GOST – The 1964 Soviet standard GOST 10859 allowed the encoding of 4-bit, 5-bit, 6-bit and 7-bit characters in ALGOL. 1968: The "Algol 68 Report" – used extant ALGOL characters, and further adopted →, ↓, ↑, □, ⌊, ⌈, ⎩, ⎧, ○, ⊥, and ¢ characters which can be found on the IBM 2741 keyboard with "typeball" (or "golf ball") print heads inserted (such as the APL golf ball). These became available in the mid-1960s while ALGOL 68 was being drafted. The report was translated into Russian, German, French, and Bulgarian, and allowed programming in languages with larger character sets, e.g., Cyrillic alphabet of the Soviet BESM-4. All ALGOL's characters are also part of the Unicode standard and most of them are available in several popular fonts. 2009 October: Unicode – The codice_3 (Decimal Exponent Symbol) for floating point notation was added to Unicode 5.2 for backward compatibility with historic Buran programme ALGOL software. ALGOL implementations. To date there have been at least 70 augmentations, extensions, derivations and sublanguages of Algol 60. The Burroughs dialects included special Bootstrapping dialects such as ESPOL and NEWP. The latter is still used for Unisys MCP system software.
AWK AWK () is a domain-specific language designed for text processing and typically used as a data extraction and reporting tool. Like sed and grep, it is a filter, and it is a standard feature of most Unix-like operating systems. The AWK language is a data-driven scripting language consisting of a set of actions to be taken against streams of textual data – either run directly on files or used as part of a pipeline – for purposes of extracting or transforming text, such as producing formatted reports. The language extensively uses the string datatype, associative arrays (that is, arrays indexed by key strings), and regular expressions. While AWK has a limited intended application domain and was especially designed to support one-liner programs, the language is Turing-complete, and even the early Bell Labs users of AWK often wrote well-structured large AWK programs. AWK was created at Bell Labs in the 1970s, and its name is derived from the surnames of its authors: Alfred Aho (author of egrep), Peter Weinberger (who worked on tiny relational databases), and Brian Kernighan. The acronym is pronounced the same as the name of the bird species auk, which is illustrated on the cover of "The AWK Programming Language". When written in all lowercase letters, as codice_1, it refers to the Unix or Plan 9 program that runs scripts written in the AWK programming language.
History. According to Brian Kernighan, one of the goals of AWK was to have a tool that would easily manipulate both numbers and strings. AWK was also inspired by Marc Rochkind's programming language that was used to search for patterns in input data, and was implemented using yacc. As one of the early tools to appear in Version 7 Unix, AWK added computational features to a Unix pipeline besides the Bourne shell, the only scripting language available in a standard Unix environment. It is one of the mandatory utilities of the Single UNIX Specification, and is required by the Linux Standard Base specification. In 1983, AWK was one of several UNIX tools available for Charles River Data Systems' UNOS operating system under Bell Laboratories license. AWK was significantly revised and expanded in 1985–88, resulting in the GNU AWK implementation written by Paul Rubin, Jay Fenlason, and Richard Stallman, released in 1988. GNU AWK may be the most widely deployed version because it is included with GNU-based Linux packages. GNU AWK has been maintained solely by Arnold Robbins since 1994. Brian Kernighan's nawk (New AWK) source was first released in 1993 unpublicized, and publicly since the late 1990s; many BSD systems use it to avoid the GPL license.
AWK was preceded by sed (1974). Both were designed for text processing. They share the line-oriented, data-driven paradigm, and are particularly suited to writing one-liner programs, due to the implicit main loop and current line variables. The power and terseness of early AWK programs – notably the powerful regular expression handling and conciseness due to implicit variables, which facilitate one-liners – together with the limitations of AWK at the time, were important inspirations for the Perl language (1987). In the 1990s, Perl became very popular, competing with AWK in the niche of Unix text-processing languages. Structure of AWK programs. An AWK program is a series of pattern action pairs, written as: where "condition" is typically an expression and "action" is a series of commands. The input is split into records, where by default records are separated by newline characters so that the input is split into lines. The program tests each record against each of the conditions in turn, and executes the "action" for each expression that is true. Either the condition or the action may be omitted. The condition defaults to matching every record. The default action is to print the record. This is the same pattern-action structure as sed.
In addition to a simple AWK expression, such as codice_2 or codice_3, the condition can be codice_4 or codice_5 causing the action to be executed before or after all records have been read, or "pattern1, pattern2" which matches the range of records starting with a record that matches "pattern1" up to and including the record that matches "pattern2" before again trying to match against "pattern1" on subsequent lines. In addition to normal arithmetic and logical operators, AWK expressions include the tilde operator, codice_6, which matches a regular expression against a string. As handy syntactic sugar, "/regexp/" without using the tilde operator matches against the current record; this syntax derives from sed, which in turn inherited it from the ed editor, where codice_7 is used for searching. This syntax of using slashes as delimiters for regular expressions was subsequently adopted by Perl and ECMAScript, and is now common. The tilde operator was also adopted by Perl. Commands. AWK commands are the statements that are substituted for "action" in the examples above. AWK commands can include function calls, variable assignments, calculations, or any combination thereof. AWK contains built-in support for many functions; many more are provided by the various flavors of AWK. Also, some flavors support the inclusion of dynamically linked libraries, which can also provide more functions.
The "print" command. The "print" command is used to output text. The output text is always terminated with a predefined string called the output record separator (ORS) whose default value is a newline. The simplest form of this command is: Although these fields ("$X") may bear resemblance to variables (the $ symbol indicates variables in the usual Unix shells and in Perl), they actually refer to the fields of the current record. A special case, "$0", refers to the entire record. In fact, the commands "codice_8" and "codice_12" are identical in functionality. The "print" command can also display the results of calculations and/or function calls: /regex_pattern/ { # Actions to perform in the event the record (line) matches the above regex_pattern print 3+2 print foobar(3) print foobar(variable) print sin(3-2) Output may be sent to a file: /regex_pattern/ { # Actions to perform in the event the record (line) matches the above regex_pattern print "expression" > "file name" or through a pipe: /regex_pattern/ {
# Actions to perform in the event the record (line) matches the above regex_pattern print "expression" | "command" Built-in variables. AWK's built-in variables include the field variables: $1, $2, $3, and so on ($0 represents the entire record). They hold the text or values in the individual text-fields in a record. Other variables include: Variables and syntax. Variable names can use any of the characters [A-Za-z0-9_], with the exception of language keywords, and cannot begin with a numeric digit. The operators "+ - * /" represent addition, subtraction, multiplication, and division, respectively. For string concatenation, simply place two variables (or string constants) next to each other. It is optional to use a space in between if string constants are involved, but two variable names placed adjacent to each other require a space in between. Double quotes delimit string constants. Statements need not end with semicolons. Finally, comments can be added to programs by using "#" as the first character on a line, or behind a command or sequence of commands.
User-defined functions. In a format similar to C, function definitions consist of the keyword codice_22, the function name, argument names and the function body. Here is an example of a function. function add_three(number) { return number + 3 This statement can be invoked as follows: (pattern) { print add_three(36) # Outputs 39 Functions can have variables that are in the local scope. The names of these are added to the end of the argument list, though values for these should be omitted when calling the function. It is convention to add some whitespace in the argument list before the local variables, to indicate where the parameters end and the local variables begin. Examples. Hello, World! Here is the customary "Hello, World!" program written in AWK: BEGIN { print "Hello, world!" exit Print lines longer than 80 characters. Print all lines longer than 80 characters. The default action is to print the current line. length($0) > 80 Count words. Count words in the input and print the number of lines, words, and characters (like wc):
words += NF chars += length + 1 # add one to account for the newline character at the end of each record (line) As there is no pattern for the first line of the program, every line of input matches by default, so the increment actions are executed for every line. codice_23 is shorthand for codice_24. Sum last word. "s" is incremented by the numeric value of "$NF", which is the last word on the line as defined by AWK's field separator (by default, white-space). "NF" is the number of fields in the current line, e.g. 4. Since "$4" is the value of the fourth field, "$NF" is the value of the last field in the line regardless of how many fields this line has, or whether it has more or fewer fields than surrounding lines. $ is actually a unary operator with the highest operator precedence. (If the line has no fields, then "NF" is 0, "$0" is the whole line, which in this case is empty apart from possible white-space, and so has the numeric value 0.) At the end of the input the "END" pattern matches, so "s" is printed. However, since there may have been no lines of input at all, in which case no value has ever been assigned to "s", it will by default be an empty string. Adding zero to a variable is an AWK idiom for coercing it from a string to a numeric value. (Concatenating an empty string is to coerce from a number to a string, e.g. "s """. Note, there's no operator to concatenate strings, they're just placed adjacently.) With the coercion the program prints "0" on an empty input, without it, an empty line is printed.
Match a range of input lines. The action statement prints each line numbered. The printf function emulates the standard C printf and works similarly to the print command described above. The pattern to match, however, works as follows: "NR" is the number of records, typically lines of input, AWK has so far read, i.e. the current line number, starting at 1 for the first line of input. "%" is the modulo operator. "NR % 4 == 1" is true for the 1st, 5th, 9th, etc., lines of input. Likewise, "NR % 4 == 3" is true for the 3rd, 7th, 11th, etc., lines of input. The range pattern is false until the first part matches, on line 1, and then remains true up to and including when the second part matches, on line 3. It then stays false until the first part matches again on line 5. Thus, the program prints lines 1,2,3, skips line 4, and then 5,6,7, and so on. For each line, it prints the line number (on a 6 character-wide field) and then the line contents. For example, when executed on this input: Rome Florence Milan Naples
Turin Venice The previous program prints: 1 Rome 2 Florence 3 Milan 5 Turin 6 Venice Printing the initial or the final part of a file. As a special case, when the first part of a range pattern is constantly true, e.g. "1", the range will start at the beginning of the input. Similarly, if the second part is constantly false, e.g. "0", the range will continue until the end of input. For example, /^--cut here--$/, 0 prints lines of input from the first line matching the regular expression "^--cut here--$", that is, a line containing only the phrase "--cut here--", to the end. Calculate word frequencies. Word frequency using associative arrays: BEGIN { FS="[^a-zA-Z]+" for (i=1; i<=NF; i++) words[tolower($i)]++ END { for (i in words) print i, words[i] The BEGIN block sets the field separator to any sequence of non-alphabetic characters. Separators can be regular expressions. After that, we get to a bare action, which performs the action on every input line. In this case, for every field on the line, we add one to the number of times that word, first converted to lowercase, appears. Finally, in the END block, we print the words with their frequencies. The line
for (i in words) creates a loop that goes through the array "words", setting "i" to each "subscript" of the array. This is different from most languages, where such a loop goes through each "value" in the array. The loop thus prints out each word followed by its frequency count. codice_25 was an addition to the One True awk (see below) made after the book was published. Match pattern from command line. This program can be represented in several ways. The first one uses the Bourne shell to make a shell script that does everything. It is the shortest of these methods: pattern="$1" shift awk '/'"$pattern"'/ { print FILENAME ":" $0 }' "$@" The codice_26 in the awk command is not protected by single quotes so that the shell does expand the variable but it needs to be put in double quotes to properly handle patterns containing spaces. A pattern by itself in the usual way checks to see if the whole line (codice_27) matches. codice_16 contains the current filename. awk has no explicit concatenation operator; two adjacent strings concatenate them. codice_27 expands to the original unchanged input line.
There are alternate ways of writing this. This shell script accesses the environment directly from within awk: export pattern="$1" shift awk '$0 ~ ENVIRON["pattern"] { print FILENAME ":" $0 }' "$@" This is a shell script that uses codice_30, an array introduced in a newer version of the One True awk after the book was published. The subscript of codice_30 is the name of an environment variable; its result is the variable's value. This is like the getenv function in various standard libraries and POSIX. The shell script makes an environment variable codice_32 containing the first argument, then drops that argument and has awk look for the pattern in each file. codice_6 checks to see if its left operand matches its right operand; codice_34 is its inverse. A regular expression is just a string and can be stored in variables. The next way uses command-line variable assignment, in which an argument to awk can be seen as an assignment to a variable: pattern="$1" shift awk '$0 ~ pattern { print FILENAME ":" $0 }' pattern="$pattern" "$@"
Or You can use the "-v var=value" command line option (e.g. "awk -v pattern="$pattern" ..."). Finally, this is written in pure awk, without help from a shell or without the need to know too much about the implementation of the awk script (as the variable assignment on command line one does), but is a bit lengthy: BEGIN { pattern = ARGV[1] for (i = 1; i < ARGC; i++) # remove first argument ARGV[i] = ARGV[i + 1] ARGC-- if (ARGC == 1) { # the pattern was the only thing, so force read from standard input (used by book) ARGC = 2 ARGV[1] = "-" The codice_4 is necessary not only to extract the first argument, but also to prevent it from being interpreted as a filename after the codice_4 block ends. codice_37, the number of arguments, is always guaranteed to be ≥1, as codice_38 is the name of the command that executed the script, most often the string codice_39. codice_40 is the empty string, codice_41. codice_42 initiates a comment that expands to the end of the line. Note the codice_43 block. awk only checks to see if it should read from standard input before it runs the command. This means that
awk 'prog' only works because the fact that there are no filenames is only checked before codice_44 is run! If you explicitly set codice_37 to 1 so that there are no arguments, awk will simply quit because it feels there are no more input files. Therefore, you need to explicitly say to read from standard input with the special filename codice_46. Self-contained AWK scripts. On Unix-like operating systems self-contained AWK scripts can be constructed using the shebang syntax. For example, a script that sends the content of a given file to standard output may be built by creating a file named codice_47 with the following content: It can be invoked with: codice_48 The codice_49 tells awk that the argument that follows is the file to read the AWK program from, which is the same flag that is used in sed. Since they are often used for one-liners, both these programs default to executing a program given as a command-line argument, rather than a separate file. Versions and implementations. AWK was originally written in 1977 and distributed with Version 7 Unix.
In 1985 its authors started expanding the language, most significantly by adding user-defined functions. The language is described in the book "The AWK Programming Language", published 1988, and its implementation was made available in releases of UNIX System V. To avoid confusion with the incompatible older version, this version was sometimes called "new awk" or "nawk". This implementation was released under a free software license in 1996 and is still maintained by Brian Kernighan (see external links below). Old versions of Unix, such as UNIX/32V, included codice_50, which converted AWK to C. Kernighan wrote a program to turn awk into ; its state is not known. The gawk manual has a list of more AWK implementations.
Asgard In Nordic mythology, Asgard (Old Norse: Ásgarðr; "Garden of the Æsir") is a location associated with the gods. It appears in several Old Norse sagas and mythological texts, including the Eddas, however it has also been suggested to be referred to indirectly in some of these sources. It is described as the fortified home of the Æsir gods and is often associated with gold imagery and contains many other locations known in Nordic mythology such as Valhöll, Iðavöllr and Hlidskjálf. In some euhemeristic accounts, Asgard is portrayed as being a city in Asia or Troy, however in other accounts that likely more accurately reflect its conception in Old Norse religion, it is depicted as not conforming to a naturalistic geographical position. In these latter accounts, it is found in a range of locations such as over the rainbow bridge Bifröst, in the middle of the world and over the sea. Etymology. The compound word "Ásgarðr" combines Old Norse "" ("god") and ("enclosure"). Possible anglicisations include: Ásgarthr, Ásgard, Ásegard, Ásgardr, Asgardr, Ásgarth, Asgarth, Esageard, and Ásgardhr.
Attestations. The Poetic Edda. Asgard is named twice in Eddic poetry. The first case is in "Hymiskviða", when Thor and Týr journey from Asgard to Hymir's hall to obtain a cauldron large enough to brew beer for a feast for Ægir and the gods. The second instance is in "Þrymskviða" when Loki is attempting to convince Thor to dress up as Freyja in order to get back Mjölnir by claiming that without his hammer to protect them, jötnar would soon be living in Asgard. "Grímnismál" contains among its cosmological descriptions, a number of abodes of the gods, such as Álfheim, Nóatún and Valhalla, which some scholars have identified as being in Asgard. Asgard is not mentioned at any point in the poem. Furthermore, "Völuspá" references Iðavöllr, one of the most common meeting places of Æsir gods, which in "Gylfaginning", Snorri locates in the centre of Asgard. The Prose Edda. Prologue. The Prose Edda's euhemeristic prologue portrays the Æsir gods as people who travelled from the East to northern territories. According to Snorri, Asgard represented the town of Troy before Greek warriors overtook it. After the defeat, Trojans moved to northern Europe, where they became a dominant group due to their "advanced technologies and culture". Eventually, other tribes began to perceive the Trojans and their leader Trór (Thor in Old Norse) as gods.
Gylfaginning. In "Gylfaginning", Snorri Sturluson describes how during the creation of the world, the gods made the earth and surrounded it with the sea. They made the sky from the skull of Ymir and settled the on the shores of the earth. They set down the brows of Ymir, forming Midgard, and in the centre of the world they built Asgard, which he identifies as Troy: After Asgard is made, the gods then built a hof named Glaðsheimr at Iðavöllr, in the centre of the burg, or walled city, with a high seat for Odin and twelve seats for other gods. It is described as like gold both on the inside and the outside, and as the best of all buildings in the world. They also built Vingólf for the female gods, which is described as both a hall and a hörgr, and a forge with which they crafted objects from gold. After Ragnarök, some gods such as Váli and Baldr will meet at Iðavöllr where Asgard once stood and discuss matters together. There they will also find in the grass the golden chess pieces that the Æsir had once owned.
Later, the section describes how an unnamed jötunn came to the gods with his stallion, Svaðilfari and offered help in building a burg for the gods in three winters, asking in return for the sun, moon, and marriage with Freyja. Despite Freyja's opposition, together the gods agree to fulfill his request if he completes his work in just one winter. As time goes on, the gods grow desperate as it becomes apparent that the jötunn will construct the burg on time. To their surprise, his stallion contributes much of the progress, swiftly moving boulders and rocks. To deal with the problem, Loki comes up with a plan whereupon he changes his appearance to that of a mare, and distracts Svaðilfari to slow down construction. Without the help of his stallion, the builder realises he cannot complete his task in time and goes into a rage, revealing his identity as a jötunn. Thor then kills the builder with Mjöllnir, before any harm to the gods is done. The chapter does not explicitly name Asgard as the fortress but they are commonly identified by scholars.