Learning Functional Programming in Go

Morphisms

A morphism is an arrow from one object (A, B, C in our example) in a category (our grouping of A, B, C). There can be more than one arrow from A to B (or from B to C, or A to C). Also, arrows can go from any object to itself; this is called the identity morphism.

• f:A→B statement is a morphism (f) from A to B
• Hom(A,B) is the collection of all arrows from A to B
• Hom(A,B) is also known as the Hom-Set of A to B
• idA:A→A is a morphism from A to A