diff --git a/Assignments/03.rkt b/Assignments/03.rkt
index 63130d6..f2f7093 100644
--- a/Assignments/03.rkt
+++ b/Assignments/03.rkt
@@ -89,7 +89,8 @@
        (interp (closureV-body lam-val)
              (BindValue (closureV-param lam-val)
                         arg-val
-                        (closureV-env lam-val))))]))
+                        (closureV-env lam-val))))]
+    [(listE lst) (listV (map (lambda (x) (interp x env)) lst))])) ;; TODO COME BACK TO
 
 (define (lookup name env)
   (type-case ValueEnv env
@@ -233,7 +234,8 @@
     [(boolTE) (boolT)]
     [(arrowTE a b) (arrowT (parse-type a)
                            (parse-type b))]
-    [(guessTE) (varT (gen-tvar-id!) (box (none)))]))
+    [(guessTE) (varT (gen-tvar-id!) (box (none)))]
+    [(listTE e) .... ]))
 (define (type-lookup name-to-find env)
   (type-case TypeEnv env
     [(EmptyTypeEnv ) (error 'type-lookup "free variable, so no type")]
@@ -321,6 +323,10 @@
            (begin
              (unify! a1 a2 expr)
              (unify! b1 b2 expr))]
+          [else (type-error expr t1 t2)])]
+       [(listT a2)
+        (type-case Type t1
+          [(listT a1) (unify! a1 a2 expr)]
           [else (type-error expr t1 t2)])])]))
 
 (define (typecheck [exp : Exp] [env : TypeEnv]) : Type
@@ -369,6 +375,7 @@
      (let* ([arg-type (parse-type te)]
             [res-type (typecheck body (BindType name arg-type env))])
        (arrowT arg-type res-type))]
+    [(listE list) .... ]
     ))
 
 ;; ----------------------------------------
@@ -525,3 +532,43 @@
   #;(test/exn (typecheck (recE 'f (arrowTE (numTE) (numTE)) (idE 'f) (appE (idE 'f) (numE 10)))
                          (EmptyTypeEnv))
               "no type"))
+
+;; New list tests
+;; ------------------------------------
+
+(module+ test
+  (test (unify! (listT (boolT)) (listT (boolT)) 'test) (void))
+  (test/exn (unify! (listT (boolT)) (listT (numT)) 'test) "no type")
+  (test/exn (unify! (boolT) (listT (numT)) 'test) "no type")
+  (test/exn (unify! (listT (numT)) (boolT) 'test) "no type"))
+
+(module+ test
+  (test (run `{list 1 2}) (listV (list (numV 1) (numV 2))))
+  (test (run `{list false true false}) (listV (list (boolV #f) (boolV #t) (boolV #f)))))
+
+(module+ test
+  ;; lists of numbers
+  (test/type `{list 1 2} (listT (numT)))
+
+  ;; report error for mixed types
+  (test/notype  `{list 1 true})
+
+  ;; infer type of list
+  (test/type `{lam {x : num} {list x}} (arrowT (numT) (listT (numT))))
+
+  ;; functions taking list parameters
+  (test/type `{lam {x : {listof num}} x}
+             (arrowT (listT (numT)) (listT (numT))))
+
+  ;; report error for mixed inferred types
+  (test/notype `{lam {x : num} {list true x}})
+
+  ;; infer type of function parameter from list element
+  (test/type `{lam {x : ?} {list x 1}} (arrowT (numT) (listT (numT))))
+
+  ;; complain about cyclic type (Y-combinator) inside list
+  (test/notype `{lam {x : ?} {list {x x}}})
+
+  ;; infer type of list from function application
+  (test/type `{{lam {x : ?} {list x}} 2} (listT (numT)))
+)