feat: add ConcatBy

slice/slice.go

@@ -1411,3 +1411,22 @@ func JoinFunc[T any](slice []T, sep string, transform func(T) T) string {
 	}
 	return buf.String()
 }
+
+// ConcatBy concats the elements of a slice into a single value using the provided separator and connector function.
+// Play: todo
+func ConcatBy[T any](slice []T, sep T, connector func(T, T) T) T {
+	var result T
+
+	if len(slice) == 0 {
+		return result
+	}
+
+	for i, v := range slice {
+		result = connector(result, v)
+		if i < len(slice)-1 {
+			result = connector(result, sep)
+		}
+	}
+
+	return result
+}

slice/slice_example_test.go

@@ -1272,3 +1272,31 @@ func ExampleJoinFunc() {
 	// Output:
 	// A, B, C
 }
+
+func ExampleConcatBy() {
+	type Person struct {
+		Name string
+		Age  int
+	}
+
+	people := []Person{
+		{Name: "Alice", Age: 30},
+		{Name: "Bob", Age: 25},
+		{Name: "Charlie", Age: 35},
+	}
+
+	sep := Person{Name: " | ", Age: 0}
+
+	personConnector := func(a, b Person) Person {
+		return Person{Name: a.Name + b.Name, Age: a.Age + b.Age}
+	}
+
+	result := ConcatBy(people, sep, personConnector)
+
+	fmt.Println(result.Name)
+	fmt.Println(result.Age)
+
+	// Output:
+	// Alice | Bob | Charlie
+	// 90
+}

slice/slice_test.go

@@ -1856,3 +1856,41 @@ func TestJoinFunc(t *testing.T) {
 		assert.Equal(expected, result)
 	})
 }
+
+func TestConcatBy(t *testing.T) {
+	t.Parallel()
+
+	assert := internal.NewAssert(t, "TestConcatBy")
+
+	t.Run("Join strings", func(t *testing.T) {
+		result := ConcatBy([]string{"Hello", "World"}, ", ", func(a, b string) string {
+			return a + b
+		})
+
+		expected := "Hello, World"
+		assert.Equal(expected, result)
+	})
+
+	t.Run("Join Person struct", func(t *testing.T) {
+		type Person struct {
+			Name string
+			Age  int
+		}
+
+		people := []Person{
+			{Name: "Alice", Age: 30},
+			{Name: "Bob", Age: 25},
+			{Name: "Charlie", Age: 35},
+		}
+		sep := Person{Name: " | ", Age: 0}
+
+		personConnector := func(a, b Person) Person {
+			return Person{Name: a.Name + b.Name, Age: a.Age + b.Age}
+		}
+
+		result := ConcatBy(people, sep, personConnector)
+
+		assert.Equal("Alice | Bob | Charlie", result.Name)
+		assert.Equal(90, result.Age)
+	})
+}