diff --git a/langext/array.go b/langext/array.go
index 430ef45..053d618 100644
--- a/langext/array.go
+++ b/langext/array.go
@@ -163,6 +163,25 @@ func ArrLast[T comparable](arr []T, comp func(v T) bool) (T, bool) {
 	return result, found
 }
 
+func ArrFirstIndex[T comparable](arr []T, needle T) int {
+	for i, v := range arr {
+		if v == needle {
+			return i
+		}
+	}
+	return -1
+}
+
+func ArrLastIndex[T comparable](arr []T, needle T) int {
+	result := -1
+	for i, v := range arr {
+		if v == needle {
+			result = i
+		}
+	}
+	return result
+}
+
 func AddToSet[T comparable](set []T, add T) []T {
 	for _, v := range set {
 		if v == add {
@@ -171,3 +190,19 @@ func AddToSet[T comparable](set []T, add T) []T {
 	}
 	return append(set, add)
 }
+
+func ArrMap[T1 any, T2 any](arr []T1, conv func(v T1) T2) []T2 {
+	r := make([]T2, len(arr))
+	for i, v := range arr {
+		r[i] = conv(v)
+	}
+	return r
+}
+
+func ArrSum[T NumberConstraint](arr []T) T {
+	var r T = 0
+	for _, v := range arr {
+		r += v
+	}
+	return r
+}