1package u
 2
 3func Filter[T any](v []T, f func(T) bool) []T {
 4	var result []T
 5
 6	for _, s := range v {
 7		if f(s) {
 8			result = append(result, s)
 9		}
10	}
11
12	return result
13}
14
15func Map[T any, V any](a []T, f func(T) V) []V {
16	result := make([]V, len(a))
17	for i, v := range a {
18		result[i] = f(v)
19	}
20	return result
21}
22
23func First[T any](v []T) (T, bool) {
24	if len(v) == 0 {
25		var zero T
26		return zero, false
27	}
28	return v[0], true
29}
30
31func FirstOrZero[T any](v []T) T {
32	if len(v) == 0 {
33		var zero T
34		return zero
35	}
36	return v[0]
37}
38
39func LastOrZero[T any](v []T) T {
40	if len(v) == 0 {
41		var zero T
42		return zero
43	}
44	return v[len(v)-1]
45}
46
47func ChunkBy[T any](items []T, chunkSize int) [][]T {
48	chunks := make([][]T, 0, (len(items)/chunkSize)+1)
49	for chunkSize < len(items) {
50		items, chunks = items[chunkSize:], append(chunks, items[0:chunkSize:chunkSize])
51	}
52	return append(chunks, items)
53}