add support for accepting typed slices

generic/slice/filter.go

@@ -4,8 +4,8 @@ package slice
 type Predicate[T any] func(T) bool
 
 // Filter returns a new slice with all elements from the given elems slice for which the Predicate is satisfied.
-func Filter[T any](elems []T, predicate Predicate[T]) []T {
-	var output []T
+func Filter[S ~[]T, T any](elems S, predicate Predicate[T]) S {
+	var output S
 
 	for _, v := range elems {
 		if predicate(v) {

generic/slice/filter_test.go

@@ -12,6 +12,8 @@ func TestFilter(t *testing.T) {
 		Valid bool
 	}
 
+	type testStructSlice []testStruct
+
 	tests := []struct {
 		name      string
 		elems     []any
@@ -40,9 +42,22 @@ func TestFilter(t *testing.T) {
 			want: []any{testStruct{ID: 1, Valid: true}, testStruct{ID: 3, Valid: true}},
 		},
 	}
+
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
 			assert.EqualValues(t, tt.want, Filter(tt.elems, tt.predicate))
 		})
 	}
+
+	t.Run("ValidTypedSlice", func(t *testing.T) {
+		assert.EqualValues(t, testStructSlice{
+			testStruct{ID: 1, Valid: true},
+			testStruct{ID: 3, Valid: true},
+		}, Filter(testStructSlice{
+			testStruct{ID: 1, Valid: true},
+			testStruct{ID: 2},
+			testStruct{ID: 3, Valid: true},
+			testStruct{ID: 4},
+		}, func(i testStruct) bool { return i.Valid }))
+	})
 }

generic/slice/find.go

@@ -6,7 +6,7 @@ const NotFound = -1
 // Find returns the first element from the given elems slice for which the Predicate is satisfied.
 // Returned can be either the zero value of type or nil(if slice of pointers is given) and the index,
 // iff found otherwise -1 is returned.
-func Find[T any](elems []T, predicate Predicate[T]) (T, int) {
+func Find[S ~[]T, T any](elems S, predicate Predicate[T]) (T, int) {
 	for i, v := range elems {
 		if predicate(v) {
 			return v, i

generic/slice/find_test.go

@@ -11,6 +11,8 @@ func TestFind(t *testing.T) {
 		ID int
 	}
 
+	type testStructSlice []testStruct
+
 	tests := []struct {
 		name      string
 		elems     []any
@@ -83,4 +85,28 @@ func TestFind(t *testing.T) {
 			}
 		})
 	}
+
+	t.Run("TypedSlices", func(t *testing.T) {
+		t.Run("ElemFound", func(t *testing.T) {
+			v, index := Find(testStructSlice{
+				testStruct{ID: 1},
+				testStruct{ID: 2},
+				testStruct{ID: 3},
+				testStruct{ID: 4},
+			}, func(i testStruct) bool { return i.ID == 2 })
+			assert.NotEqual(t, NotFound, index)
+			assert.EqualValues(t, testStruct{ID: 2}, v)
+		})
+
+		t.Run("ElemNotFound", func(t *testing.T) {
+			v, index := Find(testStructSlice{
+				testStruct{ID: 1},
+				testStruct{ID: 2},
+				testStruct{ID: 3},
+				testStruct{ID: 4},
+			}, func(i testStruct) bool { return i.ID == 5 })
+			assert.Equal(t, NotFound, index)
+			assert.EqualValues(t, testStruct{}, v)
+		})
+	})
 }

generic/slice/map.go

@@ -10,7 +10,7 @@ type MapperWithContext[T1, T2 any] func(context.Context, T1) T2
 
 // Map returns a new slice populated with the result of calling the Mapper
 // on every element in the given elems slice.
-func Map[T1, T2 any](elems []T1, mapper Mapper[T1, T2]) []T2 {
+func Map[S ~[]T1, T1, T2 any](elems S, mapper Mapper[T1, T2]) []T2 {
 	output := make([]T2, 0, len(elems))
 
 	for _, e := range elems {
@@ -22,7 +22,8 @@ func Map[T1, T2 any](elems []T1, mapper Mapper[T1, T2]) []T2 {
 
 // MapConcurrentWithContext does the same as Map, but concurrently, and receives a context.Context to be cancellable.
 // Note: For simple map operations, Map is about 50x faster than MapConcurrentWithContext.
-func MapConcurrentWithContext[T1, T2 any](ctx context.Context, elems []T1, mapper MapperWithContext[T1, T2]) []T2 {
+func MapConcurrentWithContext[S ~[]T1, T1, T2 any](
+	ctx context.Context, elems S, mapper MapperWithContext[T1, T2]) []T2 {
 	elemOrder := make(chan chan T2, len(elems))
 	output := make([]T2, 0, len(elems))
 
@@ -70,6 +71,6 @@ loop:
 
 // MapConcurrent does the same as Map, but concurrently.
 // Note: For simple map operations, Map is about 50x faster than MapConcurrent.
-func MapConcurrent[T1, T2 any](elems []T1, mapper Mapper[T1, T2]) []T2 {
+func MapConcurrent[S ~[]T1, T1, T2 any](elems S, mapper Mapper[T1, T2]) []T2 {
 	return MapConcurrentWithContext(context.Background(), elems, func(_ context.Context, e T1) T2 { return mapper(e) })
 }

generic/slice/map_test.go

@@ -12,6 +12,8 @@ type testStructA struct {
 	Value int
 }
 
+type testStructASlice []testStructA
+
 type testStructB struct {
 	Value int
 }
@@ -46,6 +48,14 @@ func TestMap(t *testing.T) {
 			assert.EqualValues(t, tt.want, Map(tt.elems, tt.mapper))
 		})
 	}
+
+	t.Run("MapTypedSlice", func(t *testing.T) {
+		assert.EqualValues(t, []testStructB{{Value: 4}, {Value: 8}, {Value: 12}}, Map(testStructASlice{
+			testStructA{Value: 2},
+			testStructA{Value: 4},
+			testStructA{Value: 6},
+		}, func(i testStructA) testStructB { return testStructB{Value: i.Value * 2} }))
+	})
 }
 
 func TestMapConcurrentWithContext(t *testing.T) {

generic/slice/reduce.go

@@ -6,7 +6,7 @@ type Accumulator[T1, T2 any] func(T2, T1) T2
 
 // Reduce iterates over the slice and executes an Accumulator function on each element.
 // The final result of running the Accumulator across all slice elements is returned.
-func Reduce[T1, T2 any](elems []T1, accumulator Accumulator[T1, T2]) T2 {
+func Reduce[S ~[]T1, T1, T2 any](elems S, accumulator Accumulator[T1, T2]) T2 {
 	var initial T2
 
 	return ReduceWithInitialValue(elems, initial, accumulator)
@@ -15,7 +15,7 @@ func Reduce[T1, T2 any](elems []T1, accumulator Accumulator[T1, T2]) T2 {
 // ReduceWithInitialValue iterates over the slice and executes an Accumulator function on each element.
 // Unlike Reduce, the initial value of the accumulator can be provided as an argument.
 // The final result of running the Accumulator across all slice elements is returned.
-func ReduceWithInitialValue[T1, T2 any](elems []T1, initial T2, accumulator Accumulator[T1, T2]) T2 {
+func ReduceWithInitialValue[S ~[]T1, T1, T2 any](elems S, initial T2, accumulator Accumulator[T1, T2]) T2 {
 	for _, v := range elems {
 		initial = accumulator(initial, v)
 	}

generic/slice/reduce_test.go

@@ -11,6 +11,8 @@ func TestReduce(t *testing.T) {
 		Value float64
 	}
 
+	type testStructSlice []testStruct
+
 	tests := []struct {
 		name        string
 		elems       []any
@@ -72,13 +74,32 @@ func TestReduce(t *testing.T) {
 			assert.Equal(t, tt.want, Reduce(tt.elems, tt.accumulator))
 		})
 	}
+
+	t.Run("FindStructWithMaxValueFromTypedSlice", func(t *testing.T) {
+		assert.EqualValues(t, testStruct{Value: 6.91}, Reduce(testStructSlice{
+			testStruct{Value: 1.02},
+			testStruct{Value: 4.2},
+			testStruct{Value: 2.01},
+			testStruct{Value: 6.91},
+			testStruct{Value: 3.14},
+			testStruct{Value: 5.3},
+		}, func(in testStruct, e testStruct) testStruct {
+			if in.Value > e.Value {
+				return in
+			}
+
+			return e
+		}))
+	})
 }
 
 func TestReduceWithInitialValue(t *testing.T) {
 	type testStruct struct {
 		Value float64
 	}
 
+	type testStructSlice []testStruct
+
 	tests := []struct {
 		name        string
 		elems       []any
@@ -126,4 +147,21 @@ func TestReduceWithInitialValue(t *testing.T) {
 			assert.Equal(t, tt.want, ReduceWithInitialValue(tt.elems, tt.initial, tt.accumulator))
 		})
 	}
+
+	t.Run("FindStructWithMaxValueFromTypedSlice", func(t *testing.T) {
+		assert.EqualValues(t, testStruct{Value: 6.91}, ReduceWithInitialValue(testStructSlice{
+			testStruct{Value: 1.02},
+			testStruct{Value: 4.2},
+			testStruct{Value: 2.01},
+			testStruct{Value: 6.91},
+			testStruct{Value: 3.14},
+			testStruct{Value: 5.3},
+		}, testStruct{Value: 0.0}, func(in testStruct, e testStruct) testStruct {
+			if in.Value > e.Value {
+				return in
+			}
+
+			return e
+		}))
+	})
 }