[project @ 2001-03-13 14:58:25 by simonpj]

----------------
	Nuke ClassContext
	----------------

This commit tidies up a long-standing inconsistency in GHC.
The context of a class or instance decl used to be restricted
to predicates of the form
	C t1 .. tn
with
	type ClassContext = [(Class,[Type])]

but everywhere else in the compiler we used

	type ThetaType = [PredType]
where PredType can be any sort of constraint (= predicate).

The inconsistency actually led to a crash, when compiling
	class (?x::Int) => C a where {}

I've tidied all this up by nuking ClassContext altogether, and using
PredType throughout.  Lots of modified files, but all in
more-or-less trivial ways.

I've also added a check that the context of a class or instance
decl doesn't include a non-inheritable predicate like (?x::Int).

Other things

 * rename constructor 'Class' from type TypeRep.Pred to 'ClassP'
   (makes it easier to grep for)

 * rename constructor HsPClass  => HsClassP
		      HsPIParam => HsIParam

1 files changed, 6 insertions, 6 deletions

diff --git a/ghc/compiler/rename/RnSource.lhs b/ghc/compiler/rename/RnSource.lhs
index fe24db11ab..491e4bf116 100644
--- a/ghc/compiler/rename/RnSource.lhs
+++ b/ghc/compiler/rename/RnSource.lhs
@@ -651,19 +651,19 @@ rnContext doc ctxt
 			   (naughtyCCallContextErr pred')	`thenRn_`
 		   returnRn pred'
 
-    bad_pred (HsPClass clas _) = getUnique clas `elem` cCallishClassKeys
+    bad_pred (HsClassP clas _) = getUnique clas `elem` cCallishClassKeys
     bad_pred other	       = False
 
 
-rnPred doc (HsPClass clas tys)
+rnPred doc (HsClassP clas tys)
   = lookupOccRn clas		`thenRn` \ clas_name ->
     rnHsTypes doc tys		`thenRn` \ tys' ->
-    returnRn (HsPClass clas_name tys')
+    returnRn (HsClassP clas_name tys')
 
-rnPred doc (HsPIParam n ty)
+rnPred doc (HsIParam n ty)
   = newIPName n			`thenRn` \ name ->
     rnHsType doc ty		`thenRn` \ ty' ->
-    returnRn (HsPIParam name ty')
+    returnRn (HsIParam name ty')
 \end{code}
 
 \begin{code}
@@ -893,7 +893,7 @@ dupClassAssertWarn ctxt (assertion : dups)
 	       ptext SLIT("in the context:")],
 	 nest 4 (pprHsContext ctxt <+> ptext SLIT("..."))]
 
-naughtyCCallContextErr (HsPClass clas _)
+naughtyCCallContextErr (HsClassP clas _)
   = sep [ptext SLIT("Can't use class") <+> quotes (ppr clas), 
 	 ptext SLIT("in a context")]
 \end{code}