Go Variadic Functions and Function Values

ExampleGo

package main

import "fmt"

func sum(nums ...int) int {
  total := 0
  for _, n := range nums {
    total += n
  }
  return total
}

func apply(nums []int, f func(int) int) []int {
  out := make([]int, 0, len(nums))
  for _, n := range nums {
    out = append(out, f(n))
  }
  return out
}

func main() {
  fmt.Println(sum(), sum(1, 2, 3))
  values := []int{4, 5, 6}
  fmt.Println(sum(values...))
  fmt.Println(apply(values, func(n int) int { return n * n }))
}

Output

0 6
15
[16 25 36]

nums ...int collects any number of arguments into a slice. Functions are values in Go, so you can pass them around, as apply does.

Quick check

What does the ... before values do in sum(values...)?

Spreads a slice into separate argumentsRepeats the callMakes the slice optional

Finish the quick check (and any code exercise) to complete this lesson, or mark it done yourself.

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