Location and Directory

[hcoop/domtool2.git] / src / tycheck.sml

diff --git a/src/tycheck.sml b/src/tycheck.sml
index 8d35e2d..152eaf7 100644 (file)
--- a/src/tycheck.sml
+++ b/src/tycheck.sml
@@ -112,9 +112,6 @@ datatype type_error =
        | UnboundVariable of string
        | WrongPred of string * pred * pred
 
-fun preface (s, d) = printd (PD.hovBox (PD.PPS.Rel 0,
-                                       [PD.string s, PD.space 1, d]))
-
 fun describe_unification_error t ue =
     case ue of
        UnifyPred (p1, p2) =>
@@ -173,6 +170,8 @@ fun predImplies (p1All as (p1, _), p2All as (p2, _)) =
       | (_, CPrefix p2) => predImplies (p1All, p2)
 
       | (CNot p1, CNot p2) => predImplies (p2, p1)
+      | (CRoot, CNot (CConst _, _)) => true
+      | (CConst s1, CNot (CConst s2, _)) => s1 <> s2
 
       | _ => false
 
@@ -281,17 +280,39 @@ fun whnorm (tAll as (t, loc)) =
        TUnif (_, ref (SOME tAll)) => whnorm tAll
       | _ => tAll
 
+fun baseCondition t =
+    case whnorm t of
+       (TBase name, _) => typeRule name
+      | (TList t, _) =>
+       (case baseCondition t of
+            NONE => NONE
+          | SOME f => SOME (fn (EList ls, _) => List.all f ls
+                             | _ => false))
+      | _ => NONE
+
 fun hasTyp (e, t1, t2) =
-    case whnorm t2 of
-       (TBase name, _) =>
-       (case typeRule name of
-            NONE => subTyp (t1, t2)
-          | SOME rule =>
-            if rule e then
-                ()
-            else
-                subTyp (t1, t2))
-      | _ => subTyp (t1, t2)
+    if (case baseCondition t2 of
+           NONE => false
+         | SOME rule => rule e) then
+       ()
+    else
+       subTyp (t1, t2)
+
+fun checkPred G (p, loc) =
+    let
+       val err = ErrorMsg.error (SOME loc)
+    in
+       case p of
+           CRoot => ()
+         | CConst s =>
+           if lookupContext G s then
+               ()
+           else
+               err ("Unbound context " ^ s)
+         | CPrefix p => checkPred G p
+         | CNot p => checkPred G p
+         | CAnd (p1, p2) => (checkPred G p1; checkPred G p2)
+    end
 
 fun checkTyp G (tAll as (t, loc)) =
     let
@@ -306,13 +327,32 @@ fun checkTyp G (tAll as (t, loc)) =
                 (TError, loc))
          | TList t => (TList (checkTyp G t), loc)
          | TArrow (d, r) => (TArrow (checkTyp G d, checkTyp G r), loc)
-         | TAction (p, d, r) => (TAction (p, SM.map (checkTyp G) d,
-                                          SM.map (checkTyp G) r), loc)
-         | TNested (p, t) => (TNested (p, checkTyp G t), loc)
+         | TAction (p, d, r) => (checkPred G p;
+                                 (TAction (p, SM.map (checkTyp G) d,
+                                           SM.map (checkTyp G) r), loc))
+         | TNested (p, t) => (checkPred G p;
+                              (TNested (p, checkTyp G t), loc))
          | TError => raise Fail "TError in parser-generated type"
          | TUnif _ => raise Fail "TUnif in parser-generated type"
     end
 
+fun envVarSetFrom v (e, _) =
+    case e of
+       ESet (v', e) =>
+       if v = v' then
+           SOME e
+       else
+           NONE
+      | EGet (_, _, e) => envVarSetFrom v e
+      | ESeq es => foldr (fn (e, found) =>
+                            case found of
+                                SOME _ => found
+                              | NONE => envVarSetFrom v e)
+                        NONE es
+      | ELocal (_, e) => envVarSetFrom v e
+
+      | _ => NONE
+
 fun checkExp G (eAll as (e, loc)) =
     let
        val dte = describe_type_error loc
@@ -446,21 +486,25 @@ fun checkExp G (eAll as (e, loc)) =
                                                        (case SM.find (d', name) of
                                                             NONE => SM.insert (d', name, t)
                                                           | SOME t' =>
-                                                            (subTyp (t, t')
+                                                            ((case envVarSetFrom name e1 of
+                                                                  NONE => subTyp (t, t')
+                                                                | SOME e => hasTyp (e, t, t'))
                                                              handle Unify ue =>
                                                                     dte (WrongType ("Shared environment variable",
                                                                                     (EVar name, loc),
-                                                                                    t,
                                                                                     t',
+                                                                                    t,
                                                                                     SOME ue));
                                                              d'))
                                                      | SOME t' =>
-                                                       (subTyp (t, t')
+                                                       ((case envVarSetFrom name e1 of
+                                                                  NONE => subTyp (t, t')
+                                                                | SOME e => hasTyp (e, t, t'))
                                                         handle Unify ue =>
                                                                dte (WrongType ("Shared environment variable",
                                                                                (EVar name, loc),
-                                                                               t,
                                                                                t',
+                                                                               t,
                                                                                SOME ue));
                                                         d'))
                                                d1 d2
@@ -504,21 +548,25 @@ fun checkExp G (eAll as (e, loc)) =
                                                        (case SM.find (d', name) of
                                                             NONE => SM.insert (d', name, t)
                                                           | SOME t' =>
-                                                            (subTyp (t, t')
+                                                            ((case envVarSetFrom name e1 of
+                                                                  NONE => subTyp (t', t)
+                                                                | SOME e => hasTyp (e, t', t))
                                                              handle Unify ue =>
                                                                     dte (WrongType ("Shared environment variable",
                                                                                     (EVar name, loc),
-                                                                                    t,
                                                                                     t',
+                                                                                    t,
                                                                                     SOME ue));
                                                              d'))
                                                      | SOME t' =>
-                                                       (subTyp (t, t')
+                                                       ((case envVarSetFrom name e1 of
+                                                                  NONE => subTyp (t', t)
+                                                                | SOME e => hasTyp (e, t', t))
                                                         handle Unify ue =>
                                                                dte (WrongType ("Shared environment variable",
                                                                                (EVar name, loc),
-                                                                               t,
                                                                                t',
+                                                                               t,
                                                                                SOME ue));
                                                         d'))
                                                d1 d2
@@ -659,8 +707,9 @@ fun checkDecl G (d, _, loc) =
                                                   SOME ue));
            bindVal G (name, to, SOME e)
        end
+      | DContext name => bindContext G name
 
-fun checkFile G tInit (ds, eo) =
+fun checkFile G tInit (_, ds, eo) =
     let
        val G' = foldl (fn (d, G) => checkDecl G d) G ds
     in