feat: add slicesx.Map extension

slicesx/filter_test.go

@@ -23,8 +23,8 @@ func TestFilter(t *testing.T) {
 		{Category: "Medicine", Laureate: "Julius Axelrod"},
 	}
 
-	filtered := Filter(nobelPrizes, func(l nobelPrize) bool {
-		return l.Category == "Medicine"
+	filtered := Filter(nobelPrizes, func(n nobelPrize) bool {
+		return n.Category == "Medicine"
 	})
 
 	assert.EqualValues(t, []nobelPrize{

slicesx/map.go

@@ -0,0 +1,9 @@
+package slicesx
+
+func Map[S ~[]E, E, T any](s S, f func(E) T) []T {
+	t := make([]T, len(s))
+	for i, e := range s {
+		t[i] = f(e)
+	}
+	return t
+}

slicesx/map_test.go

@@ -0,0 +1,42 @@
+package slicesx
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestMap(t *testing.T) {
+	type nobelPrize struct {
+		Category string
+		Laureate string
+	}
+	nobelPrizes := []nobelPrize{
+		{Category: "Chemistry", Laureate: "Luis Leloir"},
+		{Category: "Economics", Laureate: "Paul Samuelson"},
+		{Category: "Literature", Laureate: "Aleksandr Solzhenitsyn"},
+		{Category: "Peace", Laureate: "Norman Borlaug"},
+		{Category: "Physics", Laureate: "Hannes Alfvén"},
+		{Category: "Physics", Laureate: "Louis Néel"},
+		{Category: "Medicine", Laureate: "Sir Bernard Katz"},
+		{Category: "Medicine", Laureate: "Ulf von Euler"},
+		{Category: "Medicine", Laureate: "Julius Axelrod"},
+	}
+
+	lowered := Map(nobelPrizes, func(n nobelPrize) string {
+		return strings.ToLower(n.Laureate)
+	})
+
+	assert.EqualValues(t, []string{
+		"luis leloir",
+		"paul samuelson",
+		"aleksandr solzhenitsyn",
+		"norman borlaug",
+		"hannes alfvén",
+		"louis néel",
+		"sir bernard katz",
+		"ulf von euler",
+		"julius axelrod",
+	}, lowered)
+}