diff --git a/map.go b/map.go
new file mode 100644
index 0000000..0509887
--- /dev/null
+++ b/map.go
@@ -0,0 +1,46 @@
+package laniakea
+
+type HashMap[K comparable, V any] map[K]V
+
+func NewMapFrom[K comparable, V any](m map[K]V) HashMap[K, V] {
+	out := make(HashMap[K, V])
+	for k, v := range m {
+		out[k] = v
+	}
+	return out
+}
+func (m HashMap[K, V]) Len() int {
+	return len(m)
+}
+func (m HashMap[K, V]) Add(key K, val V) HashMap[K, V] {
+	m[key] = val
+	return m
+}
+func (m HashMap[K, V]) Remove(key K) HashMap[K, V] {
+	delete(m, key)
+	return m
+}
+func (m HashMap[K, V]) Get(key K) V {
+	return m[key]
+}
+func (m HashMap[K, V]) GetOrDefault(key K, def V) V {
+	v, ok := m[key]
+	if !ok {
+		return def
+	}
+	return v
+}
+func (m HashMap[K, V]) Contains(key K) bool {
+	_, ok := m[key]
+	return ok
+}
+func (m HashMap[K, V]) Filter(f func(K, V) bool) HashMap[K, V] {
+	out := make(HashMap[K, V])
+	for k, v := range m {
+		if !f(k, v) {
+			continue
+		}
+		out[k] = v
+	}
+	return out
+}
diff --git a/slice.go b/slice.go
index 219b0a2..2d62079 100644
--- a/slice.go
+++ b/slice.go
@@ -6,7 +6,7 @@ type Slice[T comparable] []T
 
 func NewSliceFrom[T comparable](slice []T) Slice[T] {
 	s := make(Slice[T], len(slice))
-	copy(s[:], slice)
+	copy(s, slice)
 	return s
 }
 func (s Slice[T]) Len() int {
@@ -21,6 +21,11 @@ func (s Slice[T]) Get(index int) T {
 func (s Slice[T]) Last() T {
 	return s.Get(s.Len() - 1)
 }
+func (s Slice[T]) Index(el T) int {
+	return slices.Index(s, el)
+}
+
+// Swap is mutable func
 func (s Slice[T]) Swap(i, j int) Slice[T] {
 	s[i], s[j] = s[j], s[i]
 	return s
@@ -55,7 +60,7 @@ func (s Slice[T]) Pop(index int) Slice[T] {
 	return out
 }
 func (s Slice[T]) Remove(el T) Slice[T] {
-	index := slices.Index(s, el)
+	index := s.Index(el)
 	if index == -1 {
 		return s
 	}
@@ -78,12 +83,20 @@ func (s Slice[T]) ToAnyArray() []any {
 	return out
 }
 
+// ForEach is mutable func
+func (s Slice[T]) ForEach(f func(e T) T) Slice[T] {
+	for i, v := range s {
+		s[i] = f(v)
+	}
+	return s
+}
+
 type Set[T comparable] []T
 
 func NewSetFrom[T comparable](slice []T) Set[T] {
 	s := make(Set[T], 0)
 	for _, v := range slice {
-		if slices.Index(slice, v) >= 0 {
+		if s.Index(v) >= 0 {
 			continue
 		}
 		s = append(s, v)
@@ -102,11 +115,14 @@ func (s Set[T]) Get(index int) T {
 func (s Set[T]) Last() T {
 	return s[s.Len()-1]
 }
+func (s Set[T]) Index(el T) int {
+	return slices.Index(s, el)
+}
 func (s Set[T]) Swap(i, j int) {
 	s[i], s[j] = s[j], s[i]
 }
 func (s Set[T]) Add(v T) Set[T] {
-	index := slices.Index(s, v)
+	index := s.Index(v)
 	if index >= 0 {
 		return s
 	}
@@ -126,7 +142,7 @@ func (s Set[T]) Pop(index int) Set[T] {
 	return out
 }
 func (s Set[T]) Remove(el T) Set[T] {
-	index := slices.Index(s, el)
+	index := s.Index(el)
 	if index == -1 {
 		return s
 	}
diff --git a/version.go b/version.go
index a98aaa7..2661f98 100644
--- a/version.go
+++ b/version.go
@@ -1,8 +1,8 @@
 package laniakea
 
 const (
-	VersionString = "0.3.8"
+	VersionString = "0.3.9"
 	VersionMajor  = 0
 	VersionMinor  = 3
-	VersionPatch  = 8
+	VersionPatch  = 9
 )