[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, 2 insertions, 2 deletions

diff --git a/ghc/compiler/rename/ParseIface.y b/ghc/compiler/rename/ParseIface.y
index 7fa4cd352e..e4bcf4b67f 100644
--- a/ghc/compiler/rename/ParseIface.y
+++ b/ghc/compiler/rename/ParseIface.y
@@ -524,8 +524,8 @@ context_list1	: class					{ [$1] }
 		| class ',' context_list1 		{ $1 : $3 }
 
 class		:: { HsPred RdrName }
-class		:  qcls_name atypes			{ (HsPClass $1 $2) }
-		|  ipvar_name '::' type			{ (HsPIParam $1 $3) }
+class		:  qcls_name atypes			{ (HsClassP $1 $2) }
+		|  ipvar_name '::' type			{ (HsIParam $1 $3) }
 
 types0		:: { [RdrNameHsType] 			{- Zero or more -}  }	
 types0		:  {- empty -}				{ [ ] }