feat(type_manipulation): add Nil (#383)

Co-authored-by: Gustavo Okuyama <gustavo.okuyama@ifood.com.br>

README.md

@@ -238,6 +238,7 @@ Type manipulation helpers:
 
 - [IsNil](#isnil)
 - [ToPtr](#toptr)
+- [Nil](#nil)
 - [EmptyableToPtr](#emptyabletoptr)
 - [FromPtr](#fromptr)
 - [FromPtrOr](#fromptror)
@@ -2443,6 +2444,15 @@ ptr := lo.ToPtr("hello world")
 // *string{"hello world"}
 ```
 
+### Nil
+
+Returns a nil pointer of type.
+
+```go
+ptr := lo.Nil[float64]()
+// nil
+```
+
 ### EmptyableToPtr
 
 Returns a pointer copy of value if it's nonzero.

type_manipulation.go

@@ -13,6 +13,11 @@ func ToPtr[T any](x T) *T {
 	return &x
 }
 
+// Nil returns a nil pointer of type.
+func Nil[T any]() *T {
+	return nil
+}
+
 // EmptyableToPtr returns a pointer copy of value if it's nonzero.
 // Otherwise, returns nil pointer.
 func EmptyableToPtr[T any](x T) *T {

type_manipulation_test.go

@@ -39,6 +39,27 @@ func TestToPtr(t *testing.T) {
 	is.Equal(*result1, []int{1, 2})
 }
 
+func TestNil(t *testing.T) {
+	t.Parallel()
+	is := assert.New(t)
+
+	nilFloat64 := Nil[float64]()
+	var expNilFloat64 *float64
+
+	nilString := Nil[string]()
+	var expNilString *string
+
+	is.Equal(expNilFloat64, nilFloat64)
+	is.Nil(nilFloat64)
+	is.NotEqual(nil, nilFloat64)
+
+	is.Equal(expNilString, nilString)
+	is.Nil(nilString)
+	is.NotEqual(nil, nilString)
+
+	is.NotEqual(nilString, nilFloat64)
+}
+
 func TestEmptyableToPtr(t *testing.T) {
 	t.Parallel()
 	is := assert.New(t)