functional_programming/CHANGELOG.md

Changelog of the functional-programming course

2025-04-08

functors.py

• restructure the notebook
• replace f in the function signatures with g to indicate regular functions and distinguish from functors
• move Maybe funtor to section More Functor instances

• add Either functor
• add unzip utility function for functors

2025-04-07

applicatives.py

• the apply method of Maybe Applicative should return None when fg or fa is None

• add sequenceL as a classmethod for Applicative and add examples for Wrapper, Maybe, List
• add description for utility functions of Applicative

• refine the implementation of IO Applicative
• reimplement get_chars with IO.sequenceL

• add an example to show that ListMonoidal is equivalent to List Applicative

2025-04-06

applicatives.py

• remove sequenceL from Applicative because it should be a classmethod but can't be generically implemented

2025-04-02

functors.py

• Migrate to python3.13

  • Replace all occurrences of

    class Functor(Generic[A])
    

    with

    class Functor[A]
    

    for conciseness

• Use fa in function signatures instead of a when fa is a Functor

applicatives.py

• 0.1.0 version of notebook 06_applicatives.py

2025-03-16

functors.py

• Use uppercased letters for Generic types, e.g. A = TypeVar("A")

• Refactor the Functor class, changing fmap and utility methods to classmethod

  For example:

  @dataclass
  class Wrapper(Functor, Generic[A]):
      value: A
  
      @classmethod
      def fmap(cls, f: Callable[[A], B], a: "Wrapper[A]") -> "Wrapper[B]":
          return Wrapper(f(a.value))
  
  >>> Wrapper.fmap(lambda x: x + 1, wrapper)
  Wrapper(value=2)
  

• Move the check_functor_law method from Functor class to a standard function

• Rename ListWrapper to List for simplicity
• Remove the Just class

• Rewrite proofs

2025-03-13

functors.py

• 0.1.0 version of notebook 05_functors

Thank Akshay and Haleshot for reviewing

2025-03-11

functors.py

• Demo version of notebook 05_functors.py