feat: add UniqMap (#527)

README.md

@@ -80,6 +80,7 @@ Supported helpers for slices:
 
 - [Filter](#filter)
 - [Map](#map)
+- [UniqMap](#uniqmap)
 - [FilterMap](#filtermap)
 - [FlatMap](#flatmap)
 - [Reduce](#reduce)
@@ -345,6 +346,23 @@ lop.Map([]int64{1, 2, 3, 4}, func(x int64, _ int) string {
 // []string{"1", "2", "3", "4"}
 ```
 
+### UniqMap
+
+UniqMap manipulates a slice and transforms it to a slice of another type with unique values.
+
+```go
+type User struct {
+    Name string
+    Age  int
+}
+users := []User{{Name: "Alex", Age: 10}, {Name: "Alex", Age: 12}, {Name: "Bob", Age: 11}, {Name: "Alice", Age: 20}}
+
+names := UniqMap(users, func(u User, index int) string {
+    return u.Name
+})
+// []string{"Alex", "Bob", "Alice"}
+```
+
 ### FilterMap
 
 Returns a slice which obtained after both filtering and mapping using the given callback function.

slice.go

@@ -33,6 +33,21 @@ func Map[T any, R any](collection []T, iteratee func(item T, index int) R) []R {
 	return result
 }
 
+// UniqMap manipulates a slice and transforms it to a slice of another type with unique values.
+func UniqMap[T any, R comparable](collection []T, iteratee func(item T, index int) R) []R {
+	result := make([]R, 0, len(collection))
+	seen := make(map[R]struct{}, len(collection))
+
+	for i, item := range collection {
+		r := iteratee(item, i)
+		if _, ok := seen[r]; !ok {
+			result = append(result, r)
+			seen[r] = struct{}{}
+		}
+	}
+	return result
+}
+
 // FilterMap returns a slice which obtained after both filtering and mapping using the given callback function.
 // The callback function should return two values:
 //   - the result of the mapping operation and

slice_example_test.go

@@ -28,6 +28,21 @@ func ExampleMap() {
 	// Output: [2 4 6 8]
 }
 
+func ExampleUniqMap() {
+	type User struct {
+		Name string
+		Age  int
+	}
+	users := []User{{Name: "Alex", Age: 10}, {Name: "Alex", Age: 12}, {Name: "Bob", Age: 11}, {Name: "Alice", Age: 20}}
+
+	result := UniqMap(users, func(u User, index int) string {
+		return u.Name
+	})
+
+	fmt.Printf("%v", result)
+	// Output: [Alex Bob Alice]
+}
+
 func ExampleFilterMap() {
 	list := []int64{1, 2, 3, 4}
 

slice_test.go

@@ -50,6 +50,23 @@ func TestMap(t *testing.T) {
 	is.Equal(result2, []string{"1", "2", "3", "4"})
 }
 
+func TestUniqMap(t *testing.T) {
+	t.Parallel()
+	is := assert.New(t)
+
+	type User struct {
+		Name string
+		age  int
+	}
+
+	users := []User{{Name: "Alice", age: 20}, {Name: "Alex", age: 21}, {Name: "Alex", age: 22}}
+	result := UniqMap(users, func(item User, index int) string {
+		return item.Name
+	})
+
+	is.Equal(result, []string{"Alice", "Alex"})
+}
+
 func TestFilterMap(t *testing.T) {
 	t.Parallel()
 	is := assert.New(t)