Learning Functional Programming in Go

A review of Category theory

Category theory is about composing functions.

A, B, C  = type = algebras/mathematical structure(homomorphisms)

Note that we no longer concern ourselves with the objects/elements inside the sets (only the arrows).

f = function = arrow that goes between objects (and maintains algebraic structure)

The f variable is a function that accepts arguments of type A and can, for example, return objects of type B.

Identity arrow (idA) goes from A to A and does nothing. f;g (composition of 1 arrow after another) is a function that accepts arguments of type A and B, and returns C.

idA;f  = f; idB  = f

There are three ways to compose two things: (f;g);h = f;(g;h).

C (category C) = set of all arrows in Category from A to C is ...