Recently Go has released an experimentation tool for generics. Here is my quick attempts.

Contains function

Playground link

package main

import "fmt"

func Contains(type T comparable)(col []T, item T) bool {
    for _, e := range col {
        if e == item {
            return true
        }
    }
    return false
}

func main() {
    fmt.Println(Contains([]string{"coffee", "tea"}, "coffee")) // true
    fmt.Println(Contains([]int{1, 2, 3}, 11)) // false
    fmt.Println(Contains([]int{1, 2, 3}, 1)) // true
}

Mappable function

Playground link

package main

import "fmt"

type Mapable(type T) struct {
    Arr []T
}

func NewMapable(type T)(col []T) Mapable(T) {
    return Mapable(T){Arr: col}
}

func (m Mapable(T)) Map(fn func(T) T) Mapable(T) {
    var newCol []T
    for _, item := range m.Arr {
        newCol = append(newCol, fn(item))
    }
    return NewMapable(newCol)
}

func main() {
    mapable := NewMapable([]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10})
    res := mapable.
        Map(func(s int) int {
            return s * 10
        }). // {[10 20 30 40 50 60 70 80 90 100]}
        Map(func(s int) int {
            return s + 20
        }) // {[30 40 50 60 70 80 90 100 110 120]}

    fmt.Println(res)
}

Hashtable

I wonder why choose () over <>, a bit too much parenthesis in my opinion. Let's discuss about it.