fn-pattern code in but not tested yet; hello compiles

7 files changed, 143 insertions, 113 deletions

diff --git a/lib/ur/list.ur b/lib/ur/list.ur
index 7527362d..90729f5c 100644
--- a/lib/ur/list.ur
+++ b/lib/ur/list.ur
@@ -83,3 +83,29 @@ fun filter (a ::: Type) f =
     in
         fil []
     end
+
+fun exists (a ::: Type) f =
+    let
+        fun ex ls =
+            case ls of
+                [] => False
+              | x :: ls =>
+                if f x then
+                    True
+                else
+                    ex ls
+    in
+        ex
+    end
+
+fun foldlMap (a ::: Type) (b ::: Type) (c ::: Type) f =
+    let
+        fun fold ls' st ls =
+            case ls of
+                [] => (rev ls', st)
+              | x :: ls =>
+                case f x st of
+                    (y, st) => fold (y :: ls') st ls
+    in
+        fold []
+    end
diff --git a/lib/ur/list.urs b/lib/ur/list.urs
index fb3407ae..28f08317 100644
--- a/lib/ur/list.urs
+++ b/lib/ur/list.urs
@@ -18,3 +18,8 @@ val mapM : m ::: (Type -> Type) -> monad m -> a ::: Type -> b ::: Type
            -> (a -> m b) -> list a -> m (list b)
 
 val filter : a ::: Type -> (a -> bool) -> t a -> t a
+
+val exists : a ::: Type -> (a -> bool) -> t a -> bool
+
+val foldlMap : a ::: Type -> b ::: Type -> c ::: Type
+               -> (a -> b -> c * b) -> b -> t a -> t c * b
diff --git a/lib/ur/top.ur b/lib/ur/top.ur
index f9b3d033..785a9c8c 100644
--- a/lib/ur/top.ur
+++ b/lib/ur/top.ur
@@ -6,44 +6,44 @@ con folder = K ==> fn r :: {K} =>
                           tf r -> tf ([nm = v] ++ r))
                       -> tf [] -> tf r
 
-fun fold K (tf :: {K} -> Type)
+fun fold [K] [tf :: {K} -> Type]
          (f : (nm :: Name -> v :: K -> r :: {K} -> [[nm] ~ r] =>
                tf r -> tf ([nm = v] ++ r)))
-         (i : tf []) (r :: {K}) (fl : folder r) = fl [tf] f i
+         (i : tf []) [r :: {K}] (fl : folder r) = fl [tf] f i
 
 structure Folder = struct
-    fun nil K (tf :: {K} -> Type)
+    fun nil [K] [tf :: {K} -> Type]
             (f : nm :: Name -> v :: K -> r :: {K} -> [[nm] ~ r] =>
              tf r -> tf ([nm = v] ++ r))
             (i : tf []) = i
 
-    fun cons K (r ::: {K}) (nm :: Name) (v :: K) [[nm] ~ r] (fold : folder r)
-             (tf :: {K} -> Type)
+    fun cons [K] [r ::: {K}] [nm :: Name] [v :: K] [[nm] ~ r] (fold : folder r)
+             [tf :: {K} -> Type]
              (f : nm :: Name -> v :: K -> r :: {K} -> [[nm] ~ r] =>
               tf r -> tf ([nm = v] ++ r))
              (i : tf []) = f [nm] [v] [r] ! (fold [tf] f i)
 
-    fun concat K (r1 ::: {K}) (r2 ::: {K}) [r1 ~ r2]
+    fun concat [K] [r1 ::: {K}] [r2 ::: {K}] [r1 ~ r2]
         (f1 : folder r1) (f2 : folder r2)
-        (tf :: {K} -> Type)
+        [tf :: {K} -> Type]
         (f : nm :: Name -> v :: K -> r :: {K} -> [[nm] ~ r] =>
          tf r -> tf ([nm = v] ++ r))
         (i : tf []) =
         f1 [fn r1' => [r1' ~ r2] => tf (r1' ++ r2)]
-           (fn (nm :: Name) (v :: K) (r1' :: {K}) [[nm] ~ r1']
+           (fn [nm :: Name] [v :: K] [r1' :: {K}] [[nm] ~ r1']
                             (acc : [r1' ~ r2] => tf (r1' ++ r2))
                             [[nm = v] ++ r1' ~ r2] =>
                f [nm] [v] [r1' ++ r2] ! acc)
            (fn [[] ~ r2] => f2 [tf] f i) !
 
-    fun mp K1 K2 (f ::: K1 -> K2) (r ::: {K1})
+    fun mp [K1] [K2] [f ::: K1 -> K2] [r ::: {K1}]
         (fold : folder r)
-        (tf :: {K2} -> Type)
+        [tf :: {K2} -> Type]
         (f : nm :: Name -> v :: K2 -> r :: {K2} -> [[nm] ~ r] =>
          tf r -> tf ([nm = v] ++ r))
         (i : tf []) =
         fold [fn r => tf (map f r)]
-        (fn (nm :: Name) (v :: K1) (rest :: {K1}) [[nm] ~ rest] (acc : tf (map f rest)) =>
+        (fn [nm :: Name] [v :: K1] [rest :: {K1}] [[nm] ~ rest] (acc : tf (map f rest)) =>
             f [nm] [f v] [map f rest] ! acc)
         i
 end
@@ -64,20 +64,20 @@ con mapU = K ==> fn f :: K => map (fn _ :: Unit => f)
 con ex = fn tf :: (Type -> Type) =>
             res ::: Type -> (choice :: Type -> tf choice -> res) -> res
 
-fun ex (tf :: (Type -> Type)) (choice :: Type) (body : tf choice) : ex tf =
- fn (res ::: Type) (f : choice :: Type -> tf choice -> res) =>
+fun ex [tf :: (Type -> Type)] [choice :: Type] (body : tf choice) : ex tf =
+ fn [res] (f : choice :: Type -> tf choice -> res) =>
     f [choice] body
 
-fun compose (t1 ::: Type) (t2 ::: Type) (t3 ::: Type)
+fun compose [t1 ::: Type] [t2 ::: Type] [t3 ::: Type]
             (f1 : t2 -> t3) (f2 : t1 -> t2) (x : t1) = f1 (f2 x)
 
-fun show_option (t ::: Type) (_ : show t) =
+fun show_option [t ::: Type] (_ : show t) =
     mkShow (fn opt : option t =>
                case opt of
                    None => ""
                  | Some x => show x)
 
-fun read_option (t ::: Type) (_ : read t) =
+fun read_option [t ::: Type] (_ : read t) =
     mkRead (fn s =>
                case s of
                    "" => None
@@ -89,79 +89,79 @@ fun read_option (t ::: Type) (_ : read t) =
                             None => None
                           | v => Some v)
 
-fun txt (t ::: Type) (ctx ::: {Unit}) (use ::: {Type}) (_ : show t) (v : t) =
+fun txt [t] [ctx ::: {Unit}] [use ::: {Type}] (_ : show t) (v : t) =
     cdata (show v)
 
-fun foldUR (tf :: Type) (tr :: {Unit} -> Type)
+fun foldUR [tf :: Type] [tr :: {Unit} -> Type]
            (f : nm :: Name -> rest :: {Unit}
                 -> [[nm] ~ rest] =>
                       tf -> tr rest -> tr ([nm] ++ rest))
-           (i : tr []) (r :: {Unit}) (fl : folder r)=
+           (i : tr []) [r :: {Unit}] (fl : folder r)=
     fl [fn r :: {Unit} => $(mapU tf r) -> tr r]
-       (fn (nm :: Name) (t :: Unit) (rest :: {Unit}) [[nm] ~ rest] acc r =>
+       (fn [nm :: Name] [t :: Unit] [rest :: {Unit}] [[nm] ~ rest] acc r =>
            f [nm] [rest] ! r.nm (acc (r -- nm)))
        (fn _ => i)
 
-fun foldUR2 (tf1 :: Type) (tf2 :: Type) (tr :: {Unit} -> Type)
+fun foldUR2 [tf1 :: Type] [tf2 :: Type] [tr :: {Unit} -> Type]
            (f : nm :: Name -> rest :: {Unit}
                 -> [[nm] ~ rest] =>
                       tf1 -> tf2 -> tr rest -> tr ([nm] ++ rest))
-           (i : tr []) (r :: {Unit}) (fl : folder r) =
+           (i : tr []) [r :: {Unit}] (fl : folder r) =
     fl [fn r :: {Unit} => $(mapU tf1 r) -> $(mapU tf2 r) -> tr r]
-       (fn (nm :: Name) (t :: Unit) (rest :: {Unit}) [[nm] ~ rest] acc r1 r2 =>
+       (fn [nm :: Name] [t :: Unit] [rest :: {Unit}] [[nm] ~ rest] acc r1 r2 =>
            f [nm] [rest] ! r1.nm r2.nm (acc (r1 -- nm) (r2 -- nm)))
        (fn _ _ => i)
 
-fun foldURX2 (tf1 :: Type) (tf2 :: Type) (ctx :: {Unit})
+fun foldURX2 [tf1 :: Type] [tf2 :: Type] [ctx :: {Unit}]
            (f : nm :: Name -> rest :: {Unit}
                 -> [[nm] ~ rest] =>
                       tf1 -> tf2 -> xml ctx [] []) =
     foldUR2 [tf1] [tf2] [fn _ => xml ctx [] []]
-            (fn (nm :: Name) (rest :: {Unit}) [[nm] ~ rest] v1 v2 acc =>
+            (fn [nm :: Name] [rest :: {Unit}] [[nm] ~ rest] v1 v2 acc =>
                 <xml>{f [nm] [rest] ! v1 v2}{acc}</xml>)
             <xml/>
 
-fun foldR K (tf :: K -> Type) (tr :: {K} -> Type)
+fun foldR [K] [tf :: K -> Type] [tr :: {K} -> Type]
            (f : nm :: Name -> t :: K -> rest :: {K}
                 -> [[nm] ~ rest] =>
                       tf t -> tr rest -> tr ([nm = t] ++ rest))
-           (i : tr []) (r :: {K}) (fl : folder r) =
+           (i : tr []) [r :: {K}] (fl : folder r) =
     fl [fn r :: {K} => $(map tf r) -> tr r]
-       (fn (nm :: Name) (t :: K) (rest :: {K}) [[nm] ~ rest] (acc : _ -> tr rest) r =>
+       (fn [nm :: Name] [t :: K] [rest :: {K}] [[nm] ~ rest] (acc : _ -> tr rest) r =>
            f [nm] [t] [rest] ! r.nm (acc (r -- nm)))
        (fn _ => i)
 
-fun foldR2 K (tf1 :: K -> Type) (tf2 :: K -> Type) (tr :: {K} -> Type)
+fun foldR2 [K] [tf1 :: K -> Type] [tf2 :: K -> Type] [tr :: {K} -> Type]
             (f : nm :: Name -> t :: K -> rest :: {K}
                  -> [[nm] ~ rest] =>
                        tf1 t -> tf2 t -> tr rest -> tr ([nm = t] ++ rest))
-            (i : tr []) (r :: {K}) (fl : folder r) =
+            (i : tr []) [r :: {K}] (fl : folder r) =
     fl [fn r :: {K} => $(map tf1 r) -> $(map tf2 r) -> tr r]
-       (fn (nm :: Name) (t :: K) (rest :: {K}) [[nm] ~ rest] 
+       (fn [nm :: Name] [t :: K] [rest :: {K}] [[nm] ~ rest] 
                         (acc : _ -> _ -> tr rest) r1 r2 =>
            f [nm] [t] [rest] ! r1.nm r2.nm (acc (r1 -- nm) (r2 -- nm)))
        (fn _ _ => i)
 
-fun foldRX K (tf :: K -> Type) (ctx :: {Unit})
+fun foldRX [K] [tf :: K -> Type] [ctx :: {Unit}]
             (f : nm :: Name -> t :: K -> rest :: {K}
                  -> [[nm] ~ rest] =>
                        tf t -> xml ctx [] []) =
     foldR [tf] [fn _ => xml ctx [] []]
-          (fn (nm :: Name) (t :: K) (rest :: {K}) [[nm] ~ rest] r acc =>
+          (fn [nm :: Name] [t :: K] [rest :: {K}] [[nm] ~ rest] r acc =>
               <xml>{f [nm] [t] [rest] ! r}{acc}</xml>)
           <xml/>
 
-fun foldRX2 K (tf1 :: K -> Type) (tf2 :: K -> Type) (ctx :: {Unit})
+fun foldRX2 [K] [tf1 :: K -> Type] [tf2 :: K -> Type] [ctx :: {Unit}]
              (f : nm :: Name -> t :: K -> rest :: {K}
                   -> [[nm] ~ rest] =>
                         tf1 t -> tf2 t -> xml ctx [] []) =
     foldR2 [tf1] [tf2] [fn _ => xml ctx [] []]
-           (fn (nm :: Name) (t :: K) (rest :: {K}) [[nm] ~ rest]
+           (fn [nm :: Name] [t :: K] [rest :: {K}] [[nm] ~ rest]
                             r1 r2 acc =>
                <xml>{f [nm] [t] [rest] ! r1 r2}{acc}</xml>)
            <xml/>
 
-fun queryI (tables ::: {{Type}}) (exps ::: {Type})
+fun queryI [tables ::: {{Type}}] [exps ::: {Type}]
            [tables ~ exps] (q : sql_query tables exps)
            (f : $(exps ++ map (fn fields :: {Type} => $fields) tables)
                 -> transaction unit) =
@@ -169,7 +169,7 @@ fun queryI (tables ::: {{Type}}) (exps ::: {Type})
           (fn fs _ => f fs)
           ()
 
-fun queryX (tables ::: {{Type}}) (exps ::: {Type}) (ctx ::: {Unit})
+fun queryX [tables ::: {{Type}}] [exps ::: {Type}] [ctx ::: {Unit}]
            [tables ~ exps] (q : sql_query tables exps)
            (f : $(exps ++ map (fn fields :: {Type} => $fields) tables)
                 -> xml ctx [] []) =
@@ -177,7 +177,7 @@ fun queryX (tables ::: {{Type}}) (exps ::: {Type}) (ctx ::: {Unit})
           (fn fs acc => return <xml>{acc}{f fs}</xml>)
           <xml/>
 
-fun queryX' (tables ::: {{Type}}) (exps ::: {Type}) (ctx ::: {Unit})
+fun queryX' [tables ::: {{Type}}] [exps ::: {Type}] [ctx ::: {Unit}]
             [tables ~ exps] (q : sql_query tables exps)
             (f : $(exps ++ map (fn fields :: {Type} => $fields) tables)
                  -> transaction (xml ctx [] [])) =
@@ -187,28 +187,28 @@ fun queryX' (tables ::: {{Type}}) (exps ::: {Type}) (ctx ::: {Unit})
               return <xml>{acc}{r}</xml>)
           <xml/>
 
-fun oneOrNoRows (tables ::: {{Type}}) (exps ::: {Type})
+fun oneOrNoRows [tables ::: {{Type}}] [exps ::: {Type}]
                 [tables ~ exps]
                 (q : sql_query tables exps)  =
     query q
           (fn fs _ => return (Some fs))
           None
 
-fun oneRow (tables ::: {{Type}}) (exps ::: {Type})
-                [tables ~ exps] (q : sql_query tables exps) =
+fun oneRow [tables ::: {{Type}}] [exps ::: {Type}]
+           [tables ~ exps] (q : sql_query tables exps) =
     o <- oneOrNoRows q;
     return (case o of
                 None => error <xml>Query returned no rows</xml>
               | Some r => r)
 
-fun eqNullable (tables ::: {{Type}}) (agg ::: {{Type}}) (exps ::: {Type})
-    (t ::: Type) (_ : sql_injectable (option t))
+fun eqNullable [tables ::: {{Type}}] [agg ::: {{Type}}] [exps ::: {Type}]
+    [t ::: Type] (_ : sql_injectable (option t))
     (e1 : sql_exp tables agg exps (option t))
     (e2 : sql_exp tables agg exps (option t)) =
     (SQL ({e1} IS NULL AND {e2} IS NULL) OR {e1} = {e2})
 
-fun eqNullable' (tables ::: {{Type}}) (agg ::: {{Type}}) (exps ::: {Type})
-    (t ::: Type) (_ : sql_injectable (option t))
+fun eqNullable' [tables ::: {{Type}}] [agg ::: {{Type}}] [exps ::: {Type}]
+    [t ::: Type] (_ : sql_injectable (option t))
     (e1 : sql_exp tables agg exps (option t))
     (e2 : option t) =
     case e2 of
diff --git a/src/elaborate.sml b/src/elaborate.sml
index 49b826eb..6f8575db 100644
--- a/src/elaborate.sml
+++ b/src/elaborate.sml
@@ -1291,7 +1291,15 @@ fun elabPat (pAll as (p, loc), (env, bound)) =
                   (L'.TRecord c, loc)),
                  (env, bound))
             end
-                                           
+
+          | L.PAnnot (p, t) =>
+            let
+                val ((p', pt), (env, bound)) = elabPat (p, (env, bound))
+                val (t', k, _) = elabCon (env, D.empty) t
+            in
+                checkPatCon env p' pt t';
+                ((p', t'), (env, bound))
+            end   
     end
 
 (* This exhaustiveness checking follows Luc Maranget's paper "Warnings for pattern matching." *)
diff --git a/src/source.sml b/src/source.sml
index 0f62cadd..bfa270d8 100644
--- a/src/source.sml
+++ b/src/source.sml
@@ -109,6 +109,7 @@ and pat' =
   | PPrim of Prim.t
   | PCon of string list * string * pat option
   | PRecord of (string * pat) list * bool
+  | PAnnot of pat * con
 
 and exp' =
     EAnnot of exp * con
diff --git a/src/source_print.sml b/src/source_print.sml
index b4f9bfd3..a16b5bb1 100644
--- a/src/source_print.sml
+++ b/src/source_print.sml
@@ -207,6 +207,12 @@ fun p_pat' par (p, _) =
                  string "}"]
         end
 
+      | PAnnot (p, t) => box [p_pat p,
+                              space,
+                              string ":",
+                              space,
+                              p_con t]
+
 and p_pat x = p_pat' false x
 
 fun p_exp' par (e, _) =
diff --git a/src/urweb.grm b/src/urweb.grm
index bfb230a6..638ede12 100644
--- a/src/urweb.grm
+++ b/src/urweb.grm
@@ -178,6 +178,11 @@ datatype prop_kind = Delete | Update
 
 datatype attr = Class of exp | Normal of con * exp
 
+fun patType loc (p : pat) =
+    case #1 p of
+        PAnnot (_, t) => t
+      | _ => (CWild (KType, loc), loc)
+
 %%
 %header (functor UrwebLrValsFn(structure Token : TOKEN))
 
@@ -290,6 +295,7 @@ datatype attr = Class of exp | Normal of con * exp
 
  | earg of exp * con -> exp * con
  | eargp of exp * con -> exp * con
+ | earga of exp * con -> exp * con
  | eargs of exp * con -> exp * con
  | eargl of exp * con -> exp * con
  | eargl2 of exp * con -> exp * con
@@ -297,6 +303,7 @@ datatype attr = Class of exp | Normal of con * exp
  | branch of pat * exp
  | branchs of (pat * exp) list
  | pat of pat
+ | patS of pat
  | pterm of pat
  | rpat of (string * pat) list * bool
  | ptuple of pat list
@@ -971,79 +978,53 @@ eargl  : eargp eargp                    (eargp1 o eargp2)
 eargl2 :                                (fn x => x)
        | eargp eargl2                   (eargp o eargl2)
 
-earg   : SYMBOL kcolon kind             (fn (e, t) =>
-                                            let
-                                                val loc = s (SYMBOLleft, kindright)
-                                            in
-                                                ((ECAbs (kcolon, SYMBOL, kind, e), loc),
-                                                 (TCFun (kcolon, SYMBOL, kind, t), loc))
-                                            end)
-       | SYMBOL COLON cexp              (fn (e, t) =>
+earg   : patS                           (fn (e, t) =>
                                             let
-                                                val loc = s (SYMBOLleft, cexpright)
+                                                val loc = s (patSleft, patSright)
+                                                val pt = patType loc patS
+
+                                                val e' = case #1 patS of
+                                                             PVar x => (EAbs (x, NONE, e), loc)
+                                                           | _ => (EAbs ("$x", SOME pt,
+                                                                         (ECase ((EVar ([], "$x", DontInfer),
+                                                                                  loc),
+                                                                                 [(patS, e)]), loc)), loc)
                                             in
-                                                ((EAbs (SYMBOL, SOME cexp, e), loc),
-                                                 (TFun (cexp, t), loc))
+                                                (e', (TFun (pt, t), loc))
                                             end)
-       | UNDER COLON cexp               (fn (e, t) =>
-                                            let
-                                                val loc = s (UNDERleft, cexpright)
-                                            in
-                                                ((EAbs ("_", SOME cexp, e), loc),
-                                                 (TFun (cexp, t), loc))
-                                            end)
-       | eargp                          (eargp)
+       | earga                          (earga)
 
-eargp  : SYMBOL                         (fn (e, t) =>
-                                            let
-                                                val loc = s (SYMBOLleft, SYMBOLright)
-                                            in
-                                                ((EAbs (SYMBOL, NONE, e), loc),
-                                                 (TFun ((CWild (KType, loc), loc), t), loc))
-                                            end)
-       | UNIT                           (fn (e, t) =>
+eargp  : pterm                          (fn (e, t) =>
                                             let
-                                                val loc = s (UNITleft, UNITright)
-                                                val t' = (TRecord (CRecord [], loc), loc)
+                                                val loc = s (ptermleft, ptermright)
+                                                val pt = patType loc pterm
+
+                                                val e' = case #1 pterm of
+                                                             PVar x => (EAbs (x, NONE, e), loc)
+                                                           | _ => (EAbs ("$x", SOME pt,
+                                                                         (ECase ((EVar ([], "$x", DontInfer),
+                                                                                  loc),
+                                                                                 [(pterm, e)]), loc)), loc)
                                             in
-                                                ((EAbs ("_", SOME t', e), loc),
-                                                 (TFun (t', t), loc))
+                                                (e', (TFun (pt, t), loc))
                                             end)
-       | UNDER                          (fn (e, t) =>
-                                            let
-                                                val loc = s (UNDERleft, UNDERright)
-                                            in
-                                                ((EAbs ("_", NONE, e), loc),
-                                                 (TFun ((CWild (KType, loc), loc), t), loc))
-                                            end)
-       | LPAREN SYMBOL kcolon kind RPAREN(fn (e, t) =>
+       | earga                          (earga)
+
+earga  : LBRACK SYMBOL RBRACK            (fn (e, t) =>
                                              let
-                                                 val loc = s (LPARENleft, RPARENright)
+                                                 val loc = s (LBRACKleft, RBRACKright)
+                                                 val kind = (KWild, loc)
+                                             in
+                                                 ((ECAbs (Implicit, SYMBOL, kind, e), loc),
+                                                  (TCFun (Implicit, SYMBOL, kind, t), loc))
+                                             end)
+       | LBRACK SYMBOL kcolon kind RBRACK(fn (e, t) =>
+                                             let
+                                                 val loc = s (LBRACKleft, RBRACKright)
                                              in
                                                  ((ECAbs (kcolon, SYMBOL, kind, e), loc),
                                                   (TCFun (kcolon, SYMBOL, kind, t), loc))
                                              end)
-       | LPAREN SYMBOL COLON cexp RPAREN  (fn (e, t) =>
-                                              let
-                                                  val loc = s (LPARENleft, RPARENright)
-                                              in
-                                                  ((EAbs (SYMBOL, SOME cexp, e), loc),
-                                                   (TFun (cexp, t), loc))
-                                              end)
-       | LPAREN UNDER COLON cexp RPAREN   (fn (e, t) =>
-                                            let
-                                                val loc = s (LPARENleft, RPARENright)
-                                            in
-                                                ((EAbs ("_", SOME cexp, e), loc),
-                                                 (TFun (cexp, t), loc))
-                                            end)
-       | LPAREN cexp TWIDDLE cexp RPAREN  (fn (e, t) =>
-                                            let
-                                                val loc = s (LPARENleft, RPARENright)
-                                            in
-                                                ((EDisjoint (cexp1, cexp2, e), loc),
-                                                 (TDisjoint (cexp1, cexp2, t), loc))
-                                            end)
        | LBRACK cexp TWIDDLE cexp RBRACK(fn (e, t) =>
                                             let
                                                 val loc = s (LBRACKleft, RBRACKright)
@@ -1051,7 +1032,7 @@ eargp  : SYMBOL                         (fn (e, t) =>
                                                 ((EDisjoint (cexp1, cexp2, e), loc),
                                                  (TDisjoint (cexp1, cexp2, t), loc))
                                             end)
-       | CSYMBOL                           (fn (e, t) =>
+       | LBRACK CSYMBOL RBRACK          (fn (e, t) =>
                                                let
                                                    val loc = s (CSYMBOLleft, CSYMBOLright)
                                                in
@@ -1214,15 +1195,18 @@ branch : pat DARROW eexp                (pat, eexp)
 branchs:                                ([])
        | BAR branch branchs             (branch :: branchs)
 
-pat    : pterm                          (pterm)
-       | cpath pterm                    (PCon (#1 cpath, #2 cpath, SOME pterm), s (cpathleft, ptermright))
-       | pterm DCOLON pat               (let
-                                             val loc = s (ptermleft, patright)
+patS   : pterm                          (pterm)
+       | pterm DCOLON patS              (let
+                                             val loc = s (ptermleft, patSright)
                                          in
                                              (PCon (["Basis"], "Cons", SOME (PRecord ([("1", pterm),
-                                                                                       ("2", pat)], false), loc)),
+                                                                                       ("2", patS)], false), loc)),
                                               loc)
                                          end)
+       | patS COLON cexp                (PAnnot (patS, cexp), s (patSleft, cexpright))
+
+pat    : patS                           (patS)
+       | cpath pterm                    (PCon (#1 cpath, #2 cpath, SOME pterm), s (cpathleft, ptermright))
 
 pterm  : SYMBOL                         (PVar SYMBOL, s (SYMBOLleft, SYMBOLright))
        | cpath                          (PCon (#1 cpath, #2 cpath, NONE), s (cpathleft, cpathright))