jusjinuk/racket-manuals · Datasets at Hugging Face

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# 15.5 Logging - If the PLTSTDOUT environment variable is defined and is not overridden by a command-line flag, it determines the level of the [log receiver](#%28tech._log._receiver%29) that propagates events to the original output port. The possible values are the same as for PLTSTDERR. The default is "none". - ...
#### 15.5.1 Creating Loggers > ``` (logger? v) → boolean? v : any/c ``` (parameter) → (-> or/c symbol? #f)``` Creates a new [logger](#%28tech._logger%29) with an optional topic and parent. The optional propagate-level and propagate-topic arguments constrain the events that are propagated from the new logger to ...
# 15.5 Logging <p>([define-logger](#%28form._%28%28lib._racket%2Fprivate%2Fmore-scheme..rkt%29._define-logger%29%29) id maybe-parent)</p></blockquote></td></tr><tr><td> </td></tr><tr><td><table data-cellpadding="0" data-cellspacing="0"><colgroup><col style="width: 20%" /><col style="width: 20%" /><col style="width: 20%...
# 15.5 Logging Defines log-id-fatal, log-id-error, log-id-warning, log-id-info, and log-id-debug as forms like [log-fatal](#%28form._%28%28lib._racket%2Fprivate%2Fmore-scheme..rkt%29._log-fatal%29%29), [log-error](#%28form._%28%28lib._racket%2Fprivate%2Fmore-scheme..rkt%29._log-error%29%29),[log-warning](#%28form._%28%...
#### 15.5.2 Logging Events > ``` (parameter) → (-> or/c symbol? #f) ``` (parameter) → (-> or/c symbol? #f)``` Reports whether any [log receiver](#%28tech._log._receiver%29) attached to logger or one of its ancestors is interested in level events (or potentially lower) for topic. If topic is #f, the result indicates...
# 15.5 Logging (parameter) → (-> list/c (or/c #f log-level/c) (or/c #f symbol?) ... ...)``` Summarizes the possible results of [log-max-level](#%28def._%28%28quote._~23~25kernel%29._log-max-level%29%29) on all possible [interned](reader.html#%28tech._interned%29) symbols. The result list contains a sequence of...
# 15.5 Logging A log receiver is a synchronizable event. It becomes ready for synchronization when a logging event is received, so use sync to receive a logged event. The log receiver’s synchronization result is an immutable vector containing four values: the level of the event as a symbol, an immutable string for the ...
#### 15.5.4 Additional Logging Functions \| \| \| \|:--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------\|--------------------------------------------------------------...
# 15.5 Logging ``` (parameter) → (-> any)``` Runs proc, outputting any logging that the execution of proc emits to [current-logger](#%28def._%28%28quote._~23~25kernel%29._current-logger%29%29) at the specified levels and topics. If #:logger is specified, intercepts events sent to that logger, otherwise uses a new ch...
# 15.5 Logging ``` (parameter) →``` Takes secs-n, a time in seconds since [the epoch](#%28tech._the._epoch%29) (like the value of ([current-seconds](#%28def._%28%28quote._~23~25kernel%29._current-seconds%29%29)), ([file-or-directory-modify-seconds](Filesystem.html#%28def._%28%28quote._~23~25kernel%29._file-or-directo...
# 15.5 Logging (parameter) → (-> or/c #f thread? 'subprocesses)``` Returns an amount of processor time in [fixnum](numbers.html#%28tech._fixnum%29) milliseconds that has been consumed by on the underlying operating system, including both user and system time. - If scope is #f, the reported time is for all Racket thr...
# 15.5 Logging ``` (current-process-milliseconds) →``` Collects timing information for a procedure application. Four values are returned: a list containing the result(s) of applying proc to the arguments in lst, the number of milliseconds of CPU time required to obtain this result, the number of “real” milliseconds ...
# 15.5 Logging (current-inexact-milliseconds) → (-> * 0.001 (current-inexact-milliseconds))``` Converts a date to a string. The returned string contains the time of day only if time?. See also [date-display-format](#%28def._%28%28lib._racket%2Fdate..rkt%29._date-display-format%29%29). > ``` (date-display-format) → (-...
# 15.5 Logging (find-seconds second minute hour day month year [ local-time?) → exact-integer? second : (integer-in 0 61) minute : (integer-in 0 59) hour : (integer-in 0 23) day : (integer-in 1 31) month : (integer-in 1 12) year : exact-no...
# 15.5 Logging ``` (parameter) → (-> environment-variables? v)``` Returns #t if v is an [environment variable set](#%28tech._environment._variable._set%29), #f otherwise. > ``` (current-environment-variables) → (-> current-environment-variables env) (current-environment-variables env) → void? env : (-> curren...
# 15.5 Logging ``` Creates a fresh environment variable set that is initialized with the given name to val mappings. > ``` (environment-variables-ref env name) → (or/c #f (and/c bytes-no-nuls? immutable?)) env : environment-variables? name : bytes-environment-variable-name?``` Returns the mapping for name i...
# 15.5 Logging On success, the result of environment-variables-set! is #<void>. If env is the initial environment variable set of the Racket process, then attempting to adjust the operating system environment-variable mapping might fail for some reason, in which case fail is called in tail position with respect to the ...
# 15.5 Logging ``` Returns an environment variable set that is initialized with the same mappings as env. > ``` (getenv name) → (or/c string-no-nuls? #f) name : string-environment-variable-name? (putenv name value) → boolean? name : string-environment-variable-name? value : string-no-nuls?``` Convenie...
# 15.5 Logging Returns information about the operating system, build mode, or machine for a running Racket. (Installation tools should use [cross-system-type](https://plt.cs.northwestern.edu/new-snapshots/new-snapshots/doc/local-redirect/index.html?doc=raco&rel=cross-system.html%23%2528def._%2528%2528lib._setup%252Fcro...
# 15.5 Logging In 'gc mode, the possible symbol results are (see also [Implementations](implementations.html)): - 'cgc — when ([system-type](#%28def._%28%28quote._~23~25kernel%29._system-type%29%29) 'vm) is 'racket - '3m — when ([system-type](#%28def._%28%28quote._~23~25kernel%29._system-type%29%29) 'vm) is 'racket...
# 15.5 Logging In 'so-suffix mode, then the result is a byte string that represents the file extension used for shared objects on the current platform. The byte string starts with a period, so it is suitable as a second argument to [path-replace-suffix](Manipulating_Paths.html#%28def._%28%28lib._racket%2Fprivate%2Fmisc...
# 15.5 Logging - 'file-level — a [filesystem change event](Filesystem.html#%28tech._filesystem._change._event%29) can track changes at the level of a file, as opposed to the file’s directory; this property is #f on Windows In 'cross mode, the result reports whether cross-platform build mode has been selected (through...
# 15.5 Logging ``` Returns a string to identify the current user’s language and country. On Unix and Mac OS, the string is five characters: two lowercase ASCII letters for the language, an underscore, and two uppercase ASCII letters for the country. On Windows, the string can be arbitrarily long, but the language and ...
# 15.5 Logging Returns an immutable string indicating the currently executing version of Racket. > ``` (banner) → (and/c string? immutable?) ``` Returns an immutable string for Racket’s start-up banner text (or the banner text for an embedding program, such as GRacket). The banner string ends with a newline. > ```...
# 15.5 Logging ``` (parameter) →``` Parses a command line according to the specification in the flag-clauses. The name-expr, if provided, should produce a path or string to be used as the program name for reporting errors when the command-line is ill-formed. It defaults to ([find-system-path](Filesystem.html#%28def....
# 15.5 Logging (non-flag) →``` Returns a string for the current machine’s hostname (including its domain). > ``` (getpid) → exact-integer? ``` Returns an integer identifying the current process within the operating system. ------------------------------------------------------------------------ # 16 Memory Manageme...
# 15.5 Logging Returns the value contained in weak-box. If the garbage collector has proven that the previous content value of weak-box was reachable only through a weak reference, then gced-v (which defaults to #f) is returned. > ``` (weak-box? v) → boolean? v : any/c ``` Returns #t if v is a weak box, #f otherw...
# 15.5 Logging Returns a new ephemeron whose key is key and whose value is initially v. > ``` (ephemeron-value ephemeron [gced-v retain-v) → any/c ephemeron : ephemeron? gced-v : any/c = #f retain-v : any/c = #f``` Returns the value contained in ephemeron. If the garbage collector has proven that the key for ephe...
# 15.5 Logging ``` Returns #t if v is an ephemeron, #f otherwise. ------------------------------------------------------------------------ # 16.3 Wills and Executors ### 16.3 Wills and Executors A will executor manages a collection of values and associated will procedures (a.k.a. finalizers). The will procedure for...
# 15.5 Logging (parameter) → (-> any/c . → . any)``` Registers the value v with the will procedure proc in the will executor executor. When v is proven unreachable, then the procedure proc is ready to be called with v as its argument via [will-execute](#%28def._%28%28quote._~23~25kernel%29._will-execute%29%29) or [wil...
# 15.5 Logging (parameter) → (-> or/c #f 'cumulative 'peak custodian?)``` Returns information about memory use: - If mode is #f (the default), the result is an estimate of the number of bytes reachable from any custodian. - If mode is 'cumulative, returns an estimate of the total number of bytes allocated since st...
# 15.5 Logging Changed in version 6.6.0.3 of package base: Added 'cumulative mode. Changed in version 8.10.0.3: Added 'peak mode. > ``` (dump-memory-stats v ...) → any v : any/c ``` (parameter) →``` Returns #t if v is a [phantom byte string](#%28tech._phantom._byte._string%29), #f otherwise. > ``` (make-phantom-...
# 17 Unsafe Operations
## 17 Unsafe Operations \| \| \| \|...
# 17 Unsafe Operations Functions provided by [racket/unsafe/ops]() are unsafe. They have certain constraints, but the constraints are not checked, which allows the system to generate and execute faster code. If arguments violate an unsafe function’s constraints, the function’s behavior and result is unpredictable, and ...
### 17.1 Unsafe Numeric Operations > ``` (unsafe-fx+ a ...) → fixnum? a : fixnum? (unsafe-fx- a b ...) → fixnum? a : fixnum? b : fixnum? (unsafe-fx* a ...) → fixnum? a : fixnum? (unsafe-fxquotient a b) → fixnum? a : fixnum? b : fixnum? (unsafe-fxremainder a b) → fixnum? a : fixnum? b : fixnum? (...
### 17.1 Unsafe Numeric Operations For fixnums: Unchecked versions of fxpopcount, fxpopcount32, and fxpopcount16. Added in version 8.5.0.6 of package base. > ``` (unsafe-fx+/wraparound a b) → fixnum? a : fixnum? b : fixnum? (unsafe-fx-/wraparound [a] b) → fixnum? a : fixnum? = 0 b : fixnum? (unsafe-fx*/wrap...
### 17.1 Unsafe Numeric Operations ``` For fixnums: Unchecked versions of fx=, fx<, fx>, fx<=, fx>=, fxmin, and fxmax. Changed in version 7.0.0.13 of package base: Allow one or more argument, instead of allowing just two. > ``` (unsafe-fl+ a ...) → flonum? a : flonum? (unsafe-fl- a b ...) → flonum? a : flonu...
### 17.1 Unsafe Numeric Operations For flonums: Unchecked versions of fl=, fl<, fl>, fl<=, fl>=, flmin, and flmax. Changed in version 7.0.0.13 of package base: Allow one or more argument, instead of allowing just two. > ``` (unsafe-flround a) → flonum? a : flonum? (unsafe-flfloor a) → flonum? a : flonum? (unsaf...
### 17.1 Unsafe Numeric Operations ``` For flonums: Unchecked (potentially) version of flsingle. Added in version 7.8.0.7 of package base. > ``` (flbit-field a start end) → exact-nonnegative-integer? a : flonum? start : (integer-in 0 64) end : (integer-in 0 64)``` For [flonums](numbers.html#%28tech._flonu...
### 17.1 Unsafe Numeric Operations > ( lambda ( c ) ( flonum? ( real-part c ) ) ) > ( lambda ( c ) ( flonum? ( imag-part c ) ) ) )``` For [flonums](numbers.html#%28tech._flonum%29): Unchecked versions of [make-flrectangular](flonums.html#%28def._%28%28lib._racket%2Fflonum..rkt%29._make-flrectangular%29%29), [flreal-par...
### 17.1 Unsafe Numeric Operations Unsafe variants of [car](pairs.html#%28def._%28%28quote._~23~25kernel%29._car%29%29), [cdr](pairs.html#%28def._%28%28quote._~23~25kernel%29._cdr%29%29), [mcar](mpairs.html#%28def._%28%28quote._~23~25kernel%29._mcar%29%29), [mcdr](mpairs.html#%28def._%28%28quote._~23~25kernel%29._mcdr%...
### 17.1 Unsafe Numeric Operations Unsafe versions of [unbox](boxes.html#%28def._%28%28quote._~23~25kernel%29._unbox%29%29) and [set-box!](boxes.html#%28def._%28%28quote._~23~25kernel%29._set-box%21%29%29), where the box\* variants can be faster but do not work on [impersonators](chaperones.html#%28tech._impersonator%2...
### 17.1 Unsafe Numeric Operations Similar to vector → immutable-vector, but potentially destroys v and reuses it space, so v must not be used after calling unsafe-vector* → immutable-vector!. Added in version 7.7.0.6 of package base. > ``` (ch) → ( → unsafe-string-ref str k)``` Unsafe versions of [string-leng...
### 17.1 Unsafe Numeric Operations ``` (parameter) → (-> parameter)``` Unsafe versions of [bytes-length](bytestrings.html#%28def._%28%28quote._~23~25kernel%29._bytes-length%29%29), [bytes-ref](bytestrings.html#%28def._%28%28quote._~23~25kernel%29._bytes-ref%29%29), [bytes-set!](bytestrings.html#%28def._%28%28quote._...
### 17.1 Unsafe Numeric Operations ``` (parameter) → (-> unsafe-f64vector-set! vec k n)``` Unsafe versions of [f64vector-ref](https://plt.cs.northwestern.edu/new-snapshots/new-snapshots/doc/local-redirect/index.html?doc=foreign&rel=homogeneous-vectors.html%23%2528def._%2528%2528lib._ffi%252Fvector..rkt%2529._f64vect...
### 17.1 Unsafe Numeric Operations ``` (parameter) → (-> unsafe-struct-set! v k val)``` Unsafe field access and update for an instance of a structure type, where the struct\* variants can be faster but do not work on [impersonators](chaperones.html#%28tech._impersonator%29). The index k must be between 0 (inclusive)...
### 17.1 Unsafe Numeric Operations (unsafe-mutable-hash-iterate-next hash pos) → (or/c #f any/c) hash : (and/c hash? (not/c immutable?) hash-strong?) pos : any/c (unsafe-mutable-hash-iterate-key hash pos) → any/c hash : (and/c hash? (not/c immutable?) hash-strong?) pos : any/c (unsafe-mutable-hash-itera...
### 17.1 Unsafe Numeric Operations (unsafe-immutable-hash-iterate-next hash pos) → (or/c #f any/c) hash : (and/c hash? immutable?) pos : any/c (unsafe-immutable-hash-iterate-key hash pos) → any/c hash : (and/c hash? immutable?) pos : any/c (unsafe-immutable-hash-iterate-k...
### 17.1 Unsafe Numeric Operations (unsafe-weak-hash-iterate-key hash pos) → any/c hash : (and/c hash? hash-weak?) pos : any/c (unsafe-weak-hash-iterate-key hash pos bad-index-v) → any/c hash : (and/c hash? hash-weak?) pos : any/c bad-index-v : any/c (unsafe-weak-hash-itera...
### 17.1 Unsafe Numeric Operations hash : (and/c hash? hash-ephemeron?) pos : any/c bad-index-v : any/c (unsafe-ephemeron-hash-iterate-value hash pos) → any/c hash : (and/c hash? hash-ephemeron?) pos : any/c (unsafe-ephemeron-hash-iterate-value hash pos bad-index-...
### 17.1 Unsafe Numeric Operations Each unsafe ...-first and ...-next procedure may return, instead of a number index, an internal representation of a view into the hash structure, enabling faster iteration. The result of these ...-first and ...-next functions should be given as pos to the corresponding unsafe accessor...
### 17.1 Unsafe Numeric Operations ``` Unsafe version of srcloc. Added in version 7.2.0.10 of package base. ### 17.4 Unsafe Extflonum Operations > ``` (unsafe-extfl+ a b) → extflonum? a : extflonum? b : extflonum? (unsafe-extfl- a b) → extflonum? a : extflonum? b : extflonum? (unsafe-extfl* a b) ...
### 17.1 Unsafe Numeric Operations (unsafe-extflceiling a) → extflonum? a : extflonum? (unsafe-extfltruncate a) → extflonum? a : extflonum?``` Unchecked (potentially) versions of [extflround](extflonums.html#%28def._%28%28lib._racket%2Fextflonum..rkt%29._extflround%29%29), [extflfloor](extflonums.html#%28de...
### 17.1 Unsafe Numeric Operations ``` Unchecked (potentially) versions of extflsin, extflcos, extfltan, extflasin, extflacos, extflatan, extfllog, extflexp, extflsqrt, and extflexpt. Currently, some of these bindings are simply aliases for the corresponding safe bindings. > ``` (unsafe-fx → extfl a) → extflonum...
### 17.5 Unsafe Impersonators and Chaperones > ``` (unsafe-impersonate-procedure proc replacement-proc prop prop-val ... ...) → (and/c procedure? impersonator?) proc : procedure? replacement-proc : procedure? prop : impersonator-property? prop-val : any``` Like [impersonate-procedur...
### 17.5 Unsafe Impersonators and Chaperones If proc is itself an impersonator that is derived from [impersonate-procedure](chaperones.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._impersonate-procedure%2A%29%29) or [chaperone-procedure](chaperones.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._c...
### 17.5 Unsafe Impersonators and Chaperones The unsafety of [unsafe-impersonate-procedure](#%28def._%28%28lib._racket%2Funsafe%2Fops..rkt%29._unsafe-impersonate-procedure%29%29) is limited to the above differences from [impersonate-procedure](chaperones.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._imperson...
### 17.5 Unsafe Impersonators and Chaperones Similarly, with the same assumptions about f, the following two procedures wrap-f1 and wrap-f2 are almost equivalent; they differ only in the error message produced when their arguments are functions that return multiple values (and that they update different global variable...
### 17.5 Unsafe Impersonators and Chaperones (unsafe-chaperone-procedure proc wrapper-proc prop prop-val ... ...) → (and/c procedure? chaperone?) proc : procedure? wrapper-proc : procedure? prop : impersonator-property? prop-val : any ``` Like unsafe-impersonate-procedure, but creates...
### 17.5 Unsafe Impersonators and Chaperones Added in version 6.9.0.2 of package base.
### 17.6 Unsafe Assertions > ``` (unsafe-assert-unreachable) → none/c``` Like [assert-unreachable](unreachable.html#%28def._%28%28quote._~23~25kernel%29._assert-unreachable%29%29), but the contract of [unsafe-assert-unreachable](#%28def._%28%28lib._racket%2Funsafe%2Fops..rkt%29._unsafe-assert-unreachable%29%29) is ...
### 17.6 Unsafe Assertions Added in version 8.0.0.11 of package base.
### 17.7 Unsafe Undefined \| \| ...
### 17.7 Unsafe Undefined The constant [unsafe-undefined](#%28def._%28%28lib._racket%2Funsafe%2Fundefined..rkt%29._unsafe-undefined%29%29) is used internally as a placeholder value. For example, it is used by [letrec](let.html#%28form._%28%28lib._racket%2Fprivate%2Fletstx-scheme..rkt%29._letrec%29%29) as a value for a ...
### 17.7 Unsafe Undefined > <table data-cellpadding="0" data-cellspacing="0"><colgroup><col style="width: 100%" /></colgroup><tbody><tr><td><blockquote> <p>value</p> <p>[unsafe-undefined](#%28def._%28%28lib._racket%2Funsafe%2Fundefined..rkt%29._unsafe-undefined%29%29) : [any/c](data-structure-contracts.html#%28def._%28...
### 17.7 Unsafe Undefined - The path produced by ([build-path](Manipulating_Paths.html#%28def._%28%28quote._~23~25kernel%29._build-path%29%29) ([find-system-path](Filesystem.html#%28def._%28%28quote._~23~25kernel%29._find-system-path%29%29) 'addon-dir) name "collects") is the first element of the default collection p...
### 17.7 Unsafe Undefined - If the PLTCOLLECTS environment variable is defined, it is combined with the default list using [path-list-string->path-list](Filesystem.html#%28def._%28%28lib._racket%2Fprivate%2Fmisc..rkt%29._path-list-string-~3epath-list%29%29), as long as the value of [use-user-specific-search-paths](#%...
### 17.7 Unsafe Undefined ``` (find-config-dir) → (-> regexp-match? #rx"[.]rkt$" file)``` Returns the path to the file indicated by file in the collection specified by the collections, where the second collection (if any) names a sub-collection, and so on. The search uses the values of [current-library-collection-li...
### 17.7 Unsafe Undefined (current-library-collection-paths) → (-> listof (and/c path? complete-path?)) (current-library-collection-paths paths) → void? paths : (-> listof (and/c path? complete-path?))``` Parameter that determines a list of complete directory paths for finding libraries (as referenced in [require...
### 17.7 Unsafe Undefined ``` (use-user-specific-search-paths) → (-> use-user-specific-search-paths on?)``` Parameter that determines whether user-specific paths, which are in the directory produced by ([find-system-path](Filesystem.html#%28def._%28%28quote._~23~25kernel%29._find-system-path%29%29) 'addon-dir), are ...
# 18.3 Interactive Help
### 18.3 Interactive Help \| \| \| \|:---...
# 18.3 Interactive Help <p>[help](#%28form._%28%28lib._racket%2Fhelp..rkt%29._help%29%29)</p></blockquote></td></tr><tr><td>([help](#%28form._%28%28lib._racket%2Fhelp..rkt%29._help%29%29) string ...)</td></tr><tr><td>([help](#%28form._%28%28lib._racket%2Fhelp..rkt%29._help%29%29) id)</td></tr><tr><td>([help](#%28form._...
# 18.3 Interactive Help searches the documentation index for references that include the phrase “web browser” or “firefox.” A ([help](#%28form._%28%28lib._racket%2Fhelp..rkt%29._help%29%29) id) form looks for documentation specific to the current binding of id. For example, > ```racket > ( require net/url ) > ( help ur...
# 18.3 Interactive Help The ([help](#%28form._%28%28lib._racket%2Fhelp..rkt%29._help%29%29) id #:from module-path) variant is similar to ([help](#%28form._%28%28lib._racket%2Fhelp..rkt%29._help%29%29) id), but using only the exports of module-path. (The module-path module is required [for-label](require.html#%28form._%...
# 18.4 Interaction Configuration
### 18.4 Interaction Configuration \| \| ...
# 18.4 Interaction Configuration ``` (parameter) → (-> e.g., in a tool that uses racket/enter)``` Procedure variant of [enter!](#%28form._%28%28lib._racket%2Fenter..rkt%29._enter%21%29%29), where verbosity is passed along to [dynamic-rerequire](#%28def._%28%28lib._racket%2Frerequire..rkt%29._dynamic-rerequire%29%29)...
# 18.4 Interaction Configuration (current-error-port) → (-> string? . → . any)``` A [parameter](eval-model.html#%28tech._parameter%29) that determines the way that trace output is displayed. The string given to proc is a trace; it does not end with a newline, but it may contain internal newlines. Each call or result i...
# 18.4 Interaction Configuration ``` (current-trace-print-args) → (-> symbol? list? (listof keyword?) list? number? void?) (current-trace-print-args trace-print-args) → void? trace-print-args : (-> symbol? list? (listof keyword?) list? number? void?)``` The value of this ...
# 18.4 Interaction Configuration (current-prefix-in) → (-> current-prefix-in prefix) (current-prefix-in prefix) → void? prefix : (-> current-prefix-in prefix)``` This string is used by the default value of [current-trace-print-args](#%28def._%28%28lib._racket%2Ftrace..rkt%29._current-trace-print-args%29%29) indic...

# 15.5 Logging - If the PLTSTDOUT environment variable is defined and is not overridden by a command-line flag, it determines the level of the [log receiver](#%28tech._log._receiver%29) that propagates events to the original output port. The possible values are the same as for PLTSTDERR. The default is "none". - ...

#### 15.5.1 Creating Loggers > ``` (logger? v) → boolean? v : any/c ``` (parameter) → (-> or/c symbol? #f)``` Creates a new [logger](#%28tech._logger%29) with an optional topic and parent. The optional propagate-level and propagate-topic arguments constrain the events that are propagated from the new logger to ...

# 15.5 Logging <p>([define-logger](#%28form._%28%28lib._racket%2Fprivate%2Fmore-scheme..rkt%29._define-logger%29%29) id maybe-parent)</p></blockquote></td></tr><tr><td> </td></tr><tr><td><table data-cellpadding="0" data-cellspacing="0"><colgroup><col style="width: 20%" /><col style="width: 20%" /><col style="width: 20%...

# 15.5 Logging Defines log-id-fatal, log-id-error, log-id-warning, log-id-info, and log-id-debug as forms like [log-fatal](#%28form._%28%28lib._racket%2Fprivate%2Fmore-scheme..rkt%29._log-fatal%29%29), [log-error](#%28form._%28%28lib._racket%2Fprivate%2Fmore-scheme..rkt%29._log-error%29%29),[log-warning](#%28form._%28%...

#### 15.5.2 Logging Events > ``` (parameter) → (-> or/c symbol? #f) ``` (parameter) → (-> or/c symbol? #f)``` Reports whether any [log receiver](#%28tech._log._receiver%29) attached to logger or one of its ancestors is interested in level events (or potentially lower) for topic. If topic is #f, the result indicates...

# 15.5 Logging (parameter) → (-> list/c (or/c #f log-level/c) (or/c #f symbol?) ... ...)``` Summarizes the possible results of [log-max-level](#%28def._%28%28quote._~23~25kernel%29._log-max-level%29%29) on all possible [interned](reader.html#%28tech._interned%29) symbols. The result list contains a sequence of...

# 15.5 Logging A log receiver is a synchronizable event. It becomes ready for synchronization when a logging event is received, so use sync to receive a logged event. The log receiver’s synchronization result is an immutable vector containing four values: the level of the event as a symbol, an immutable string for the ...

#### 15.5.4 Additional Logging Functions | | | |:--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------------------------------------------------------------...

# 15.5 Logging ``` (parameter) → (-> any)``` Runs proc, outputting any logging that the execution of proc emits to [current-logger](#%28def._%28%28quote._~23~25kernel%29._current-logger%29%29) at the specified levels and topics. If #:logger is specified, intercepts events sent to that logger, otherwise uses a new ch...

# 15.5 Logging ``` (parameter) →``` Takes secs-n, a time in seconds since [the epoch](#%28tech._the._epoch%29) (like the value of ([current-seconds](#%28def._%28%28quote._~23~25kernel%29._current-seconds%29%29)), ([file-or-directory-modify-seconds](Filesystem.html#%28def._%28%28quote._~23~25kernel%29._file-or-directo...

# 15.5 Logging (parameter) → (-> or/c #f thread? 'subprocesses)``` Returns an amount of processor time in [fixnum](numbers.html#%28tech._fixnum%29) milliseconds that has been consumed by on the underlying operating system, including both user and system time. - If scope is #f, the reported time is for all Racket thr...

# 15.5 Logging ``` (current-process-milliseconds) →``` Collects timing information for a procedure application. Four values are returned: a list containing the result(s) of applying proc to the arguments in lst, the number of milliseconds of CPU time required to obtain this result, the number of “real” milliseconds ...

# 15.5 Logging (current-inexact-milliseconds) → (-> * 0.001 (current-inexact-milliseconds))``` Converts a date to a string. The returned string contains the time of day only if time?. See also [date-display-format](#%28def._%28%28lib._racket%2Fdate..rkt%29._date-display-format%29%29). > ``` (date-display-format) → (-...

# 15.5 Logging (find-seconds second minute hour day month year [ local-time?) → exact-integer? second : (integer-in 0 61) minute : (integer-in 0 59) hour : (integer-in 0 23) day : (integer-in 1 31) month : (integer-in 1 12) year : exact-no...

# 15.5 Logging ``` (parameter) → (-> environment-variables? v)``` Returns #t if v is an [environment variable set](#%28tech._environment._variable._set%29), #f otherwise. > ``` (current-environment-variables) → (-> current-environment-variables env) (current-environment-variables env) → void? env : (-> curren...

# 15.5 Logging ``` Creates a fresh environment variable set that is initialized with the given name to val mappings. > ``` (environment-variables-ref env name) → (or/c #f (and/c bytes-no-nuls? immutable?)) env : environment-variables? name : bytes-environment-variable-name?``` Returns the mapping for name i...

# 15.5 Logging On success, the result of environment-variables-set! is #<void>. If env is the initial environment variable set of the Racket process, then attempting to adjust the operating system environment-variable mapping might fail for some reason, in which case fail is called in tail position with respect to the ...

# 15.5 Logging ``` Returns an environment variable set that is initialized with the same mappings as env. > ``` (getenv name) → (or/c string-no-nuls? #f) name : string-environment-variable-name? (putenv name value) → boolean? name : string-environment-variable-name? value : string-no-nuls?``` Convenie...

# 15.5 Logging Returns information about the operating system, build mode, or machine for a running Racket. (Installation tools should use [cross-system-type](https://plt.cs.northwestern.edu/new-snapshots/new-snapshots/doc/local-redirect/index.html?doc=raco&rel=cross-system.html%23%2528def._%2528%2528lib._setup%252Fcro...

# 15.5 Logging In 'gc mode, the possible symbol results are (see also [Implementations](implementations.html)): - 'cgc — when ([system-type](#%28def._%28%28quote._~23~25kernel%29._system-type%29%29) 'vm) is 'racket - '3m — when ([system-type](#%28def._%28%28quote._~23~25kernel%29._system-type%29%29) 'vm) is 'racket...

# 15.5 Logging In 'so-suffix mode, then the result is a byte string that represents the file extension used for shared objects on the current platform. The byte string starts with a period, so it is suitable as a second argument to [path-replace-suffix](Manipulating_Paths.html#%28def._%28%28lib._racket%2Fprivate%2Fmisc...

# 15.5 Logging - 'file-level — a [filesystem change event](Filesystem.html#%28tech._filesystem._change._event%29) can track changes at the level of a file, as opposed to the file’s directory; this property is #f on Windows In 'cross mode, the result reports whether cross-platform build mode has been selected (through...

# 15.5 Logging ``` Returns a string to identify the current user’s language and country. On Unix and Mac OS, the string is five characters: two lowercase ASCII letters for the language, an underscore, and two uppercase ASCII letters for the country. On Windows, the string can be arbitrarily long, but the language and ...

# 15.5 Logging Returns an immutable string indicating the currently executing version of Racket. > ``` (banner) → (and/c string? immutable?) ``` Returns an immutable string for Racket’s start-up banner text (or the banner text for an embedding program, such as GRacket). The banner string ends with a newline. > ```...

# 15.5 Logging ``` (parameter) →``` Parses a command line according to the specification in the flag-clauses. The name-expr, if provided, should produce a path or string to be used as the program name for reporting errors when the command-line is ill-formed. It defaults to ([find-system-path](Filesystem.html#%28def....

# 15.5 Logging (non-flag) →``` Returns a string for the current machine’s hostname (including its domain). > ``` (getpid) → exact-integer? ``` Returns an integer identifying the current process within the operating system. ------------------------------------------------------------------------ # 16 Memory Manageme...

# 15.5 Logging Returns the value contained in weak-box. If the garbage collector has proven that the previous content value of weak-box was reachable only through a weak reference, then gced-v (which defaults to #f) is returned. > ``` (weak-box? v) → boolean? v : any/c ``` Returns #t if v is a weak box, #f otherw...

# 15.5 Logging Returns a new ephemeron whose key is key and whose value is initially v. > ``` (ephemeron-value ephemeron [gced-v retain-v) → any/c ephemeron : ephemeron? gced-v : any/c = #f retain-v : any/c = #f``` Returns the value contained in ephemeron. If the garbage collector has proven that the key for ephe...

# 15.5 Logging ``` Returns #t if v is an ephemeron, #f otherwise. ------------------------------------------------------------------------ # 16.3 Wills and Executors ### 16.3 Wills and Executors A will executor manages a collection of values and associated will procedures (a.k.a. finalizers). The will procedure for...

# 15.5 Logging (parameter) → (-> any/c . → . any)``` Registers the value v with the will procedure proc in the will executor executor. When v is proven unreachable, then the procedure proc is ready to be called with v as its argument via [will-execute](#%28def._%28%28quote._~23~25kernel%29._will-execute%29%29) or [wil...

# 15.5 Logging (parameter) → (-> or/c #f 'cumulative 'peak custodian?)``` Returns information about memory use: - If mode is #f (the default), the result is an estimate of the number of bytes reachable from any custodian. - If mode is 'cumulative, returns an estimate of the total number of bytes allocated since st...

# 15.5 Logging Changed in version 6.6.0.3 of package base: Added 'cumulative mode. Changed in version 8.10.0.3: Added 'peak mode. > ``` (dump-memory-stats v ...) → any v : any/c ``` (parameter) →``` Returns #t if v is a [phantom byte string](#%28tech._phantom._byte._string%29), #f otherwise. > ``` (make-phantom-...

# 17 Unsafe Operations

## 17 Unsafe Operations | | | |...

# 17 Unsafe Operations Functions provided by [racket/unsafe/ops]() are unsafe. They have certain constraints, but the constraints are not checked, which allows the system to generate and execute faster code. If arguments violate an unsafe function’s constraints, the function’s behavior and result is unpredictable, and ...

### 17.1 Unsafe Numeric Operations > ``` (unsafe-fx+ a ...) → fixnum? a : fixnum? (unsafe-fx- a b ...) → fixnum? a : fixnum? b : fixnum? (unsafe-fx* a ...) → fixnum? a : fixnum? (unsafe-fxquotient a b) → fixnum? a : fixnum? b : fixnum? (unsafe-fxremainder a b) → fixnum? a : fixnum? b : fixnum? (...

### 17.1 Unsafe Numeric Operations For fixnums: Unchecked versions of fxpopcount, fxpopcount32, and fxpopcount16. Added in version 8.5.0.6 of package base. > ``` (unsafe-fx+/wraparound a b) → fixnum? a : fixnum? b : fixnum? (unsafe-fx-/wraparound [a] b) → fixnum? a : fixnum? = 0 b : fixnum? (unsafe-fx*/wrap...

### 17.1 Unsafe Numeric Operations ``` For fixnums: Unchecked versions of fx=, fx<, fx>, fx<=, fx>=, fxmin, and fxmax. Changed in version 7.0.0.13 of package base: Allow one or more argument, instead of allowing just two. > ``` (unsafe-fl+ a ...) → flonum? a : flonum? (unsafe-fl- a b ...) → flonum? a : flonu...

### 17.1 Unsafe Numeric Operations For flonums: Unchecked versions of fl=, fl<, fl>, fl<=, fl>=, flmin, and flmax. Changed in version 7.0.0.13 of package base: Allow one or more argument, instead of allowing just two. > ``` (unsafe-flround a) → flonum? a : flonum? (unsafe-flfloor a) → flonum? a : flonum? (unsaf...

### 17.1 Unsafe Numeric Operations ``` For flonums: Unchecked (potentially) version of flsingle. Added in version 7.8.0.7 of package base. > ``` (flbit-field a start end) → exact-nonnegative-integer? a : flonum? start : (integer-in 0 64) end : (integer-in 0 64)``` For [flonums](numbers.html#%28tech._flonu...

### 17.1 Unsafe Numeric Operations > ( lambda ( c ) ( flonum? ( real-part c ) ) ) > ( lambda ( c ) ( flonum? ( imag-part c ) ) ) )``` For [flonums](numbers.html#%28tech._flonum%29): Unchecked versions of [make-flrectangular](flonums.html#%28def._%28%28lib._racket%2Fflonum..rkt%29._make-flrectangular%29%29), [flreal-par...

### 17.1 Unsafe Numeric Operations Unsafe variants of [car](pairs.html#%28def._%28%28quote._~23~25kernel%29._car%29%29), [cdr](pairs.html#%28def._%28%28quote._~23~25kernel%29._cdr%29%29), [mcar](mpairs.html#%28def._%28%28quote._~23~25kernel%29._mcar%29%29), [mcdr](mpairs.html#%28def._%28%28quote._~23~25kernel%29._mcdr%...

### 17.1 Unsafe Numeric Operations Unsafe versions of [unbox](boxes.html#%28def._%28%28quote._~23~25kernel%29._unbox%29%29) and [set-box!](boxes.html#%28def._%28%28quote._~23~25kernel%29._set-box%21%29%29), where the box\* variants can be faster but do not work on [impersonators](chaperones.html#%28tech._impersonator%2...

### 17.1 Unsafe Numeric Operations Similar to vector → immutable-vector, but potentially destroys v and reuses it space, so v must not be used after calling unsafe-vector* → immutable-vector!. Added in version 7.7.0.6 of package base. > ``` (ch) → ( → unsafe-string-ref str k)``` Unsafe versions of [string-leng...

### 17.1 Unsafe Numeric Operations ``` (parameter) → (-> parameter)``` Unsafe versions of [bytes-length](bytestrings.html#%28def._%28%28quote._~23~25kernel%29._bytes-length%29%29), [bytes-ref](bytestrings.html#%28def._%28%28quote._~23~25kernel%29._bytes-ref%29%29), [bytes-set!](bytestrings.html#%28def._%28%28quote._...

### 17.1 Unsafe Numeric Operations ``` (parameter) → (-> unsafe-f64vector-set! vec k n)``` Unsafe versions of [f64vector-ref](https://plt.cs.northwestern.edu/new-snapshots/new-snapshots/doc/local-redirect/index.html?doc=foreign&rel=homogeneous-vectors.html%23%2528def._%2528%2528lib._ffi%252Fvector..rkt%2529._f64vect...

### 17.1 Unsafe Numeric Operations ``` (parameter) → (-> unsafe-struct-set! v k val)``` Unsafe field access and update for an instance of a structure type, where the struct\* variants can be faster but do not work on [impersonators](chaperones.html#%28tech._impersonator%29). The index k must be between 0 (inclusive)...

### 17.1 Unsafe Numeric Operations (unsafe-mutable-hash-iterate-next hash pos) → (or/c #f any/c) hash : (and/c hash? (not/c immutable?) hash-strong?) pos : any/c (unsafe-mutable-hash-iterate-key hash pos) → any/c hash : (and/c hash? (not/c immutable?) hash-strong?) pos : any/c (unsafe-mutable-hash-itera...

### 17.1 Unsafe Numeric Operations (unsafe-immutable-hash-iterate-next hash pos) → (or/c #f any/c) hash : (and/c hash? immutable?) pos : any/c (unsafe-immutable-hash-iterate-key hash pos) → any/c hash : (and/c hash? immutable?) pos : any/c (unsafe-immutable-hash-iterate-k...

### 17.1 Unsafe Numeric Operations (unsafe-weak-hash-iterate-key hash pos) → any/c hash : (and/c hash? hash-weak?) pos : any/c (unsafe-weak-hash-iterate-key hash pos bad-index-v) → any/c hash : (and/c hash? hash-weak?) pos : any/c bad-index-v : any/c (unsafe-weak-hash-itera...

### 17.1 Unsafe Numeric Operations hash : (and/c hash? hash-ephemeron?) pos : any/c bad-index-v : any/c (unsafe-ephemeron-hash-iterate-value hash pos) → any/c hash : (and/c hash? hash-ephemeron?) pos : any/c (unsafe-ephemeron-hash-iterate-value hash pos bad-index-...

### 17.1 Unsafe Numeric Operations Each unsafe ...-first and ...-next procedure may return, instead of a number index, an internal representation of a view into the hash structure, enabling faster iteration. The result of these ...-first and ...-next functions should be given as pos to the corresponding unsafe accessor...

### 17.1 Unsafe Numeric Operations ``` Unsafe version of srcloc. Added in version 7.2.0.10 of package base. ### 17.4 Unsafe Extflonum Operations > ``` (unsafe-extfl+ a b) → extflonum? a : extflonum? b : extflonum? (unsafe-extfl- a b) → extflonum? a : extflonum? b : extflonum? (unsafe-extfl* a b) ...

### 17.1 Unsafe Numeric Operations (unsafe-extflceiling a) → extflonum? a : extflonum? (unsafe-extfltruncate a) → extflonum? a : extflonum?``` Unchecked (potentially) versions of [extflround](extflonums.html#%28def._%28%28lib._racket%2Fextflonum..rkt%29._extflround%29%29), [extflfloor](extflonums.html#%28de...

### 17.1 Unsafe Numeric Operations ``` Unchecked (potentially) versions of extflsin, extflcos, extfltan, extflasin, extflacos, extflatan, extfllog, extflexp, extflsqrt, and extflexpt. Currently, some of these bindings are simply aliases for the corresponding safe bindings. > ``` (unsafe-fx → extfl a) → extflonum...

### 17.5 Unsafe Impersonators and Chaperones > ``` (unsafe-impersonate-procedure proc replacement-proc prop prop-val ... ...) → (and/c procedure? impersonator?) proc : procedure? replacement-proc : procedure? prop : impersonator-property? prop-val : any``` Like [impersonate-procedur...

### 17.5 Unsafe Impersonators and Chaperones If proc is itself an impersonator that is derived from [impersonate-procedure*](chaperones.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._impersonate-procedure%2A%29%29) or [chaperone-procedure*](chaperones.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._c...

### 17.5 Unsafe Impersonators and Chaperones The unsafety of [unsafe-impersonate-procedure](#%28def._%28%28lib._racket%2Funsafe%2Fops..rkt%29._unsafe-impersonate-procedure%29%29) is limited to the above differences from [impersonate-procedure](chaperones.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._imperson...

### 17.5 Unsafe Impersonators and Chaperones Similarly, with the same assumptions about f, the following two procedures wrap-f1 and wrap-f2 are almost equivalent; they differ only in the error message produced when their arguments are functions that return multiple values (and that they update different global variable...

### 17.5 Unsafe Impersonators and Chaperones (unsafe-chaperone-procedure proc wrapper-proc prop prop-val ... ...) → (and/c procedure? chaperone?) proc : procedure? wrapper-proc : procedure? prop : impersonator-property? prop-val : any ``` Like unsafe-impersonate-procedure, but creates...

### 17.5 Unsafe Impersonators and Chaperones Added in version 6.9.0.2 of package base.

### 17.6 Unsafe Assertions > ``` (unsafe-assert-unreachable) → none/c``` Like [assert-unreachable](unreachable.html#%28def._%28%28quote._~23~25kernel%29._assert-unreachable%29%29), but the contract of [unsafe-assert-unreachable](#%28def._%28%28lib._racket%2Funsafe%2Fops..rkt%29._unsafe-assert-unreachable%29%29) is ...

### 17.6 Unsafe Assertions Added in version 8.0.0.11 of package base.

### 17.7 Unsafe Undefined | | ...

### 17.7 Unsafe Undefined The constant [unsafe-undefined](#%28def._%28%28lib._racket%2Funsafe%2Fundefined..rkt%29._unsafe-undefined%29%29) is used internally as a placeholder value. For example, it is used by [letrec](let.html#%28form._%28%28lib._racket%2Fprivate%2Fletstx-scheme..rkt%29._letrec%29%29) as a value for a ...

### 17.7 Unsafe Undefined > <table data-cellpadding="0" data-cellspacing="0"><colgroup><col style="width: 100%" /></colgroup><tbody><tr><td><blockquote> <p>value</p> <p>[unsafe-undefined](#%28def._%28%28lib._racket%2Funsafe%2Fundefined..rkt%29._unsafe-undefined%29%29) : [any/c](data-structure-contracts.html#%28def._%28...

### 17.7 Unsafe Undefined - The path produced by ([build-path](Manipulating_Paths.html#%28def._%28%28quote._~23~25kernel%29._build-path%29%29) ([find-system-path](Filesystem.html#%28def._%28%28quote._~23~25kernel%29._find-system-path%29%29) 'addon-dir) name "collects") is the first element of the default collection p...

### 17.7 Unsafe Undefined - If the PLTCOLLECTS environment variable is defined, it is combined with the default list using [path-list-string->path-list](Filesystem.html#%28def._%28%28lib._racket%2Fprivate%2Fmisc..rkt%29._path-list-string-~3epath-list%29%29), as long as the value of [use-user-specific-search-paths](#%...

### 17.7 Unsafe Undefined ``` (find-config-dir) → (-> regexp-match? #rx"[.]rkt$" file)``` Returns the path to the file indicated by file in the collection specified by the collections, where the second collection (if any) names a sub-collection, and so on. The search uses the values of [current-library-collection-li...

### 17.7 Unsafe Undefined (current-library-collection-paths) → (-> listof (and/c path? complete-path?)) (current-library-collection-paths paths) → void? paths : (-> listof (and/c path? complete-path?))``` Parameter that determines a list of complete directory paths for finding libraries (as referenced in [require...

### 17.7 Unsafe Undefined ``` (use-user-specific-search-paths) → (-> use-user-specific-search-paths on?)``` Parameter that determines whether user-specific paths, which are in the directory produced by ([find-system-path](Filesystem.html#%28def._%28%28quote._~23~25kernel%29._find-system-path%29%29) 'addon-dir), are ...

# 18.3 Interactive Help

### 18.3 Interactive Help | | | |:---...

# 18.3 Interactive Help <p>[help](#%28form._%28%28lib._racket%2Fhelp..rkt%29._help%29%29)</p></blockquote></td></tr><tr><td>([help](#%28form._%28%28lib._racket%2Fhelp..rkt%29._help%29%29) string ...)</td></tr><tr><td>([help](#%28form._%28%28lib._racket%2Fhelp..rkt%29._help%29%29) id)</td></tr><tr><td>([help](#%28form._...

# 18.3 Interactive Help searches the documentation index for references that include the phrase “web browser” or “firefox.” A ([help](#%28form._%28%28lib._racket%2Fhelp..rkt%29._help%29%29) id) form looks for documentation specific to the current binding of id. For example, > ```racket > ( require net/url ) > ( help ur...

# 18.3 Interactive Help The ([help](#%28form._%28%28lib._racket%2Fhelp..rkt%29._help%29%29) id #:from module-path) variant is similar to ([help](#%28form._%28%28lib._racket%2Fhelp..rkt%29._help%29%29) id), but using only the exports of module-path. (The module-path module is required [for-label](require.html#%28form._%...

# 18.4 Interaction Configuration

### 18.4 Interaction Configuration | | ...

# 18.4 Interaction Configuration ``` (parameter) → (-> e.g., in a tool that uses racket/enter)``` Procedure variant of [enter!](#%28form._%28%28lib._racket%2Fenter..rkt%29._enter%21%29%29), where verbosity is passed along to [dynamic-rerequire](#%28def._%28%28lib._racket%2Frerequire..rkt%29._dynamic-rerequire%29%29)...

# 18.4 Interaction Configuration (current-error-port) → (-> string? . → . any)``` A [parameter](eval-model.html#%28tech._parameter%29) that determines the way that trace output is displayed. The string given to proc is a trace; it does not end with a newline, but it may contain internal newlines. Each call or result i...

# 18.4 Interaction Configuration ``` (current-trace-print-args) → (-> symbol? list? (listof keyword?) list? number? void?) (current-trace-print-args trace-print-args) → void? trace-print-args : (-> symbol? list? (listof keyword?) list? number? void?)``` The value of this ...

# 18.4 Interaction Configuration (current-prefix-in) → (-> current-prefix-in prefix) (current-prefix-in prefix) → void? prefix : (-> current-prefix-in prefix)``` This string is used by the default value of [current-trace-print-args](#%28def._%28%28lib._racket%2Ftrace..rkt%29._current-trace-print-args%29%29) indic...