go genericsメモ

go 1.18でchunk?が書きやすくなったのでメモ。

import (
	"fmt"
)

func chunks[T any](l []T, n int) chan []T {
	ch := make(chan []T)
	go func() {
		for i := 0; i < len(l); i += n {
			fromIdx := i
			toIdx := i + n
			if toIdx > len(l) {
				toIdx = len(l)
			}
			ch <- l[fromIdx:toIdx]
		}
		close(ch)
	}()
	return ch
}

func main() {
	mm := []map[string]interface{}{
		{"a": 1, "b": 2},
		{"a": 3, "b": 4},
		{"a": 5, "b": 6},
		{"a": 7, "b": 8},
		{"a": 9, "b": 10},
	}

	for m := range chunks(mm, 3) {
		log.Printf("m %v", m)
	}

	nums := []int{0, 1, 2, 3, 4, 5, 6, 7, 8, 9}
	for n := range chunks(nums, 3) {
		log.Printf("n %v", n)
	}
}