add mlish/sweet-map.rkt test

tapl/tests/mlish/sweet-map.rkt

@@ -0,0 +1,20 @@
+#lang sweet-exp "../../mlish.rkt"
+
+define
+  sum [lst : (List Int)] → Int
+  match lst with
+    [] -> 0
+    x :: xs ->
+      {x + sum(xs)}
+
+define
+  map [f : (→ X Y)] [lst : (List X)] → (List Y)
+  match lst with
+    [] -> nil
+    x :: xs ->
+      cons
+        f x
+        map f xs
+
+sum
+  map string->number (list "1" "2" "3")