Learning Functional Programming in Go

Build a 12-hour clock functor

We'll build a 12-hour clock functor like this one:

Structure	A clock with 12 places for the hours
Transformation operation	f(x) = x + 12, where x is the hour

First, let’s examine the functor implementation:

// src/functor/clock.gopackage functorimport (   "fmt")

Define our ClockFunctor interface to include a single function (Map):

type ClockFunctor interface {   Map(f func(int) int) ClockFunctor}

Create a container to hold our list of 12 hours:

type hourContainer struct {   hours []int}

When called, Map will be executed/applied to each element in the container:

func (box hourContainer) Map(f func(int) int) ClockFunctor ...