diff --git a/immut/list/list.mbt b/immut/list/list.mbt
index cfb26887..4b91d46d 100644
--- a/immut/list/list.mbt
+++ b/immut/list/list.mbt
@@ -1025,3 +1025,7 @@ pub impl[X : @quickcheck.Arbitrary] @quickcheck.Arbitrary for T[X] with arbitrar
 ) {
   @quickcheck.Arbitrary::arbitrary(size, rs) |> from_array
 }
+
+pub fn singleton[A](x : A) -> T[A] {
+  Cons(x, Nil)
+}
diff --git a/immut/list/list.mbti b/immut/list/list.mbti
index b43784a4..e6885301 100644
--- a/immut/list/list.mbti
+++ b/immut/list/list.mbti
@@ -6,6 +6,8 @@ alias @moonbitlang/core/quickcheck as @quickcheck
 // Values
 fn repeat[A](Int, A) -> T[A]
 
+fn singleton[A](A) -> T[A]
+
 fn unfold[A, S]((S) -> (A, S)?, ~init : S) -> T[A]
 
 fn unzip[A, B](T[(A, B)]) -> (T[A], T[B])
diff --git a/immut/list/list_test.mbt b/immut/list/list_test.mbt
index bfee5f02..74123179 100644
--- a/immut/list/list_test.mbt
+++ b/immut/list/list_test.mbt
@@ -21,7 +21,8 @@ test "from_array" {
 
 test "length" {
   let ls = @list.of([1, 2, 3, 4, 5])
-  inspect!(ls.length(), content="5")
+  @json.inspect!(ls.length(), content=5)
+  @json.inspect!(@list.singleton(11), content=[11])
 }
 
 test "iter" {