Streaming Reduce, Map, and Collect in Go

main.go

package main

import (
	"fmt"
	"strconv"
)

type Power struct {
	up int
}

func main() {
	s := []int{2, 3, 5, 7, 11, 13}
	fmt.Println("s ==", s)

	// Filter
	f := func(nums []int) <-chan int {
		dest := make(chan int)
		go func() {
			for _, v := range nums {
				if v > 3 && v < 13 {
					dest <- v
				}
			}
			close(dest)
		}()
		return dest
	}(s[0:])

	// Map
	m := func(y <-chan int) <-chan Power {
		dest := make(chan Power)
		go func() {
			for v := range y {
				dest <- Power{v}
			}
			close(dest)
		}()
		return dest
	}(f)

	// Collect
	res := func(x <-chan Power) string {
		powers := "The powers: "
		pow := 0

		for v := range x {
			pow += v.up
		}

		return powers + strconv.Itoa(pow)
	}(m)

	fmt.Println(res)
}