Acing the Technical Interview in #golang https://aphyr.com/posts/340-acing-the-technical-interview

list.go

package list

import (
	"fmt"
	"io"
)

// generics - swap out V1 for a new implementation
type V1 int32
type I1 interface {
	Get() V1
	Next() I1
}
type T1 V1
type N1 func(bool) I1

func (t T1) Get() V1  { return V1(t) }
func (t T1) Next() I1 { return nil }
func (l N1) Get() V1  { return l(true).Get() }
func (l N1) Next() I1 { return l(false) }

var e I1

func Cons(h, t I1) N1 {
	return func(q bool) I1 {
		if q {
			return h
		}
		return t
	}
}

func Nth(l I1, n int) V1 {
	switch n {
	case 0:
		return l.Get()
	default:
		return Nth(l.Next(), n-1)
	}
}

func Print(l I1, w io.Writer) {
	fmt.Fprint(w, "(")
	for l != e {
		fmt.Fprint(w, l.Get())
		l = l.Next()
		if l != e {
			fmt.Fprint(w, " ")
		}
	}
	fmt.Fprint(w, ")")
}

func Reverse(l I1) I1 {
	return reverse(e, l)
}

func reverse(r, l I1) I1 {
	if l == e {
		return r
	}
	return reverse(Cons(T1(l.Get()), r), l.Next())
}

list_test.go

package list_test

import "fmt"
import (
	"localhost.localdomain/list"
	"os"
)

func ExampleCons() {
	l := list.Cons(list.T1(1), list.Cons(list.T1(2), nil))
	fmt.Println(l.Get())
	fmt.Println(l.Next().Get())
	// Output:
	// 1
	// 2
}

func ExampleNth() {
	l := list.Cons(list.T1(1), list.Cons(list.T1(2), nil))
	l = list.Cons(list.T1(3), l)
	fmt.Println(list.Nth(l, 1))
	fmt.Println(list.Nth(l, 2))
	// Output:
	// 1
	// 2
}


func ExamplePrint() {
	l := list.Cons(list.T1(1), list.Cons(list.T1(2), list.Cons(list.T1(3), nil)))
	list.Print(l, os.Stdout)
	// Output:
	// (1 2 3)
}

func ExampleReverse() {
	l := list.Cons(list.T1(1), list.Cons(list.T1(2), list.Cons(list.T1(3), nil)))
	list.Print(list.Reverse(l), os.Stdout)
	// Output:
	// (3 2 1)
}