// run // Copyright 2021 The Go Authors. All rights reserved. // Use of this source code is governed by a BSD-style // license that can be found in the LICENSE file. package main import ( "fmt" "reflect" "strconv" ) // Map calls the function f on every element of the slice s, // returning a new slice of the results. func mapper[F, T any](s []F, f func(F) T) []T { r := make([]T, len(s)) for i, v := range s { r[i] = f(v) } return r } func main() { got := mapper([]int{1, 2, 3}, strconv.Itoa) want := []string{"1", "2", "3"} if !reflect.DeepEqual(got, want) { panic(fmt.Sprintf("got %s, want %s", got, want)) } fgot := mapper([]float64{2.5, 2.3, 3.5}, func(f float64) string { return strconv.FormatFloat(f, 'f', -1, 64) }) fwant := []string{"2.5", "2.3", "3.5"} if !reflect.DeepEqual(fgot, fwant) { panic(fmt.Sprintf("got %s, want %s", fgot, fwant)) } }