allow lowlevel and match

crates/compiler/test_mono/src/tests.rs

@@ -3013,3 +3013,40 @@ fn rb_tree_fbip() {
         "#
     )
 }
+
+#[mono_test]
+fn specialize_after_match() {
+    indoc!(
+        r#"
+        app "test" provides [main] to "./platform"
+
+        main = 
+            listA : LinkedList Str
+            listA = Nil
+            
+            listB : LinkedList Str
+            listB = Nil
+
+            longestLinkedList listA listB
+
+        LinkedList a : [Cons a (LinkedList a), Nil]
+
+        longestLinkedList : LinkedList a, LinkedList a -> Nat
+        longestLinkedList = \listA, listB -> when listA is
+            Nil -> linkedListLength listB
+            Cons a aa -> when listB is
+                Nil -> linkedListLength listA
+                Cons b bb -> 
+                    lengthA = (linkedListLength aa) + 1
+                    lengthB = linkedListLength listB
+                    if lengthA > lengthB
+                        then lengthA
+                        else lengthB
+        
+        linkedListLength : LinkedList a -> Nat
+        linkedListLength = \list -> when list is
+            Nil -> 0
+            Cons _ rest -> 1 + linkedListLength rest
+        "#
+    )
+}