Comments and layout

[ghc-hetmet.git] / compiler / coreSyn / CoreUtils.lhs

diff --git a/compiler/coreSyn/CoreUtils.lhs b/compiler/coreSyn/CoreUtils.lhs
index 27813a2..38e4a11 100644 (file)
--- a/compiler/coreSyn/CoreUtils.lhs
+++ b/compiler/coreSyn/CoreUtils.lhs
@@ -633,15 +633,15 @@ exprIsHNF (Var v)         -- NB: There are no value args at this point
        -- A worry: what if an Id's unfolding is just itself: 
        -- then we could get an infinite loop...
 
-exprIsHNF (Lit l)           = True
-exprIsHNF (Type ty)         = True     -- Types are honorary Values; 
-                                       -- we don't mind copying them
-exprIsHNF (Lam b e)         = isRuntimeVar b || exprIsHNF e
-exprIsHNF (Note _ e)        = exprIsHNF e
-exprIsHNF (Cast e co)        = exprIsHNF e
+exprIsHNF (Lit l)         = True
+exprIsHNF (Type ty)       = True       -- Types are honorary Values; 
+                                       -- we don't mind copying them
+exprIsHNF (Lam b e)       = isRuntimeVar b || exprIsHNF e
+exprIsHNF (Note _ e)      = exprIsHNF e
+exprIsHNF (Cast e co)      = exprIsHNF e
 exprIsHNF (App e (Type _)) = exprIsHNF e
 exprIsHNF (App e a)        = app_is_value e [a]
-exprIsHNF other             = False
+exprIsHNF other                   = False
 
 -- There is at least one value argument
 app_is_value (Var fun) args
@@ -762,16 +762,21 @@ exprIsConApp_maybe (Cast expr co)
        -- The left-hand one must be a T, because exprIsConApp returned True
        -- but the right-hand one might not be.  (Though it usually will.)
 
-    let (from_ty, to_ty)           = coercionKind co
-       (from_tc, _from_tc_arg_tys) = splitTyConApp from_ty
+    let (from_ty, to_ty)          = coercionKind co
+       (from_tc, from_tc_arg_tys) = splitTyConApp from_ty
                -- The inner one must be a TyConApp
     in
-    ASSERT( from_tc == dataConTyCon dc )
-
     case splitTyConApp_maybe to_ty of {
        Nothing -> Nothing ;
-       Just (to_tc, _to_tc_arg_tys) | from_tc /= to_tc  -> Nothing
-                                    | otherwise  ->
+       Just (to_tc, to_tc_arg_tys) 
+               | from_tc /= to_tc -> Nothing
+               -- These two Nothing cases are possible; we might see 
+               --      (C x y) `cast` (g :: T a ~ S [a]),
+               -- where S is a type function.  In fact, exprIsConApp
+               -- will probably not be called in such circumstances,
+               -- but there't nothing wrong with it 
+
+               | otherwise  ->
     let
        tc_arity = tyConArity from_tc
 
@@ -804,10 +809,12 @@ exprIsConApp_maybe (Cast expr co)
 
     in
     ASSERT( length univ_args == tc_arity )
+    ASSERT( from_tc == dataConTyCon dc )
+    ASSERT( and (zipWith coreEqType [t | Type t <- univ_args] from_tc_arg_tys) )
     ASSERT( all isTypeArg (univ_args ++ ex_args) )
     ASSERT2( equalLength val_args arg_tys, ppr dc $$ ppr dc_tyvars $$ ppr dc_ex_tyvars $$ ppr arg_tys $$ ppr dc_args $$ ppr univ_args $$ ppr ex_args $$ ppr val_args $$ ppr arg_tys  )
 
-    Just (dc, univ_args ++ ex_args ++ new_co_args ++ new_val_args)
+    Just (dc, map Type to_tc_arg_tys ++ ex_args ++ new_co_args ++ new_val_args)
     }}
 
 exprIsConApp_maybe (Note _ expr)
@@ -1233,6 +1240,7 @@ exprIsBig (Lit _)      = False
 exprIsBig (Var v)      = False
 exprIsBig (Type t)     = False
 exprIsBig (App f a)    = exprIsBig f || exprIsBig a
+exprIsBig (Cast e _)   = exprIsBig e   -- Hopefully coercions are not too big!
 exprIsBig other               = True
 \end{code}