main.go

package slicefunk

func Map[T, U any](s []T, f func(T) U) []U {
	r := make([]U, len(s))
	for i, v := range s {
		r[i] = f(v)
	}
	return r
}

func Filter[T any](s []T, f func(T) bool) []T {
	r := make([]T, len(s))
	counter := 0
	for i := 0; i < len(s); i++ {
		if f(s[i]) {
			r[counter] = s[i]
			counter++
		}
	}
	return r[:counter]
}

func Unique[T comparable](s []T) []T {
	inResult := make(map[T]bool)
	var result []T
	for _, str := range s {
		if _, ok := inResult[str]; !ok {
			inResult[str] = true
			result = append(result, str)
		}
	}
	return result
}

func Flatten[T any](s [][]T) []T {
	itemCount := 0
	for i := 0; i < len(s); i++ {
		itemCount = itemCount + len(s[i])
	}

	r := make([]T, itemCount)
	idx := 0
	for i := 0; i < len(s); i++ {
		for j := 0; j < len(s[i]); j++ {
			r[idx] = s[i][j]
			idx++
		}
	}
	return r
}

func FlatMap[T, U any](s [][]T, f func(T) U) []U {
	return Flatten(Map(s, func(t []T) []U { return Map(t, f) }))
}