feat: contains

README.md

@@ -1,4 +1,21 @@
 # Underscore
 
-A port from the `underscore.js` library based on generics brought by `go1.18`.
+`underscore` is a `Go` library that provides useful functional programming helpers without extending any built-in
+objects.
 
+It is mostly a port from the `underscore.js` library based on generics brought by `go1.18`.
+
+## Functions
+
+`underscore` provides 100s of functions that support your favorite functional helpers
+
+### Collections
+
+- `map`
+- `filter`
+- `reduce`
+- `each`
+- `some`
+- `every`
+- `find`
+- `contains` (only numerics values at the moment)

contains.go

@@ -0,0 +1,14 @@
+package underscore
+
+type numbers interface {
+	int | int8 | int16 | int32 | int64 | uint | uint8 | uint16 | uint32 | uint64 | float32 | float64
+}
+
+func Contains[T numbers](values []T, value T) bool {
+	for _, v := range values {
+		if v == value {
+			return true
+		}
+	}
+	return false
+}

contains_test.go

@@ -0,0 +1,14 @@
+package underscore_test
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	u "github.com/rjNemo/underscore"
+)
+
+func TestContains(t *testing.T) {
+	nums := []int{1, 3, 5, 7, 9}
+	assert.True(t, u.Contains(nums, 5))
+}