Your goal in this kata is to implement a difference function, which subtracts one list from another and returns the result.

TypeScript

function arrayDiff(a: number[], b: number[]): number[] {
    return a.filter(e => !b.includes(e));
}

console.log(arrayDiff([3, 4], [3]));

Go

package main

import (
	"fmt"
)

func arrayDiff(a []int, b []int) []int {
	diff := []int{}
	for _, e := range a {
		if !contains(b, e) {
			diff = append(diff, e)
		}
	}
	return diff
}

func contains(arr []int, val int) bool {
	for _, el := range arr {
		if el == val {
			return true
		}
	}
	return false
}

func main() {
	fmt.Println(arrayDiff([]int{3, 4}, []int{3}))
}

Python

def array_diff(a, b):
    return [e for e in a if e not in b]

print(array_diff([3, 4], [3]))

PHP

function arrayDiff($a, $b) {
    return array_filter($a, function($e) use ($b) {
        return !in_array($e, $b);
    });
}

echo print_r(arrayDiff([3, 4], [3]));

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