feat: partition

README.md

@@ -21,3 +21,4 @@ It is mostly a port from the `underscore.js` library based on generics brought b
 - `contains` (only numerics values at the moment)
 - `max`
 - `min`
+- `partition`

partition.go

@@ -0,0 +1,17 @@
+package underscore
+
+// Partition splits the slice into two slices: one whose elements all satisfy predicate
+// and one whose elements all do not satisfy predicate.
+func Partition[T any](values []T, predicate func(T) bool) ([]T, []T) {
+	keep := make([]T, 0)
+	reject := make([]T, 0)
+
+	for _, v := range values {
+		if predicate(v) {
+			keep = append(keep, v)
+		} else {
+			reject = append(reject, v)
+		}
+	}
+	return keep, reject
+}

partition_test.go

@@ -0,0 +1,22 @@
+package underscore_test
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	u "github.com/rjNemo/underscore"
+)
+
+func TestPartition(t *testing.T) {
+	nums := []int{0, 1, 2, 3, 4, 5, 6, 7, 8, 9}
+	isEven := func(n int) bool { return n%2 == 0 }
+
+	wantEvens := []int{0, 2, 4, 6, 8}
+	wantOdds := []int{1, 3, 5, 7, 9}
+
+	evens, odds := u.Partition(nums, isEven)
+
+	assert.Equal(t, wantEvens, evens)
+	assert.Equal(t, wantOdds, odds)
+}