diff --git a/fold.go b/fold.go
index 3981d5c..035796b 100644
--- a/fold.go
+++ b/fold.go
@@ -1,9 +1,22 @@
 package lambda
 
 func Foldl[T any](xs []T, fx func(T, T) T) T {
-	return *new(T)
+	if len(xs) < 1 {
+		return *new(T)
+	}
+	for i := 1; i < len(xs); i++ {
+		xs[0] = fx(xs[0], xs[i])
+	}
+	return xs[0]
 }
 
 func Foldr[T any](xs []T, fx func(T, T) T) T {
-	return *new(T)
+	if len(xs) < 1 {
+		return *new(T)
+	}
+	li := len(xs) - 1
+	for i := li - 1; i >= 0; i-- {
+		xs[li] = fx(xs[li], xs[i])
+	}
+	return xs[li]
 }