From: audreyt@audreyt.org <unknown>
Date: Sun, 24 Sep 2006 12:31:51 +0000 (+0000)
Subject: Comment-only: Fix a typo, and note that the PredTy case on SplitTyConApp_maybe was... 
X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=commitdiff_plain;h=2fff69381d951c08a42e512722c3633d9ba556d0

Comment-only: Fix a typo, and note that the PredTy case on SplitTyConApp_maybe was added as a kluge.
---

diff --git a/compiler/typecheck/TcType.lhs b/compiler/typecheck/TcType.lhs
index 888452b..c10c2eb 100644
--- a/compiler/typecheck/TcType.lhs
+++ b/compiler/typecheck/TcType.lhs
@@ -10,7 +10,7 @@ compiler.  These parts
 		newtypes, and predicates are meaningful. 
 	* look through usage types
 
-The "tc" prefix is for "typechechecker", because the type checker
+The "tc" prefix is for "TypeChecker", because the type checker
 is the principal client.
 
 \begin{code}
@@ -713,10 +713,16 @@ tcSplitTyConApp_maybe ty | Just ty' <- tcView ty = tcSplitTyConApp_maybe ty'
 tcSplitTyConApp_maybe (TyConApp tc tys) = Just (tc, tys)
 tcSplitTyConApp_maybe (FunTy arg res)   = Just (funTyCon, [arg,res])
 tcSplitTyConApp_maybe (AppTy arg res)   = Just (funTyCon, [arg,res])
-tcSplitTyConApp_maybe (PredTy (ClassP _ [ty']))   = tcSplitTyConApp_maybe ty'
 	-- Newtypes are opaque, so they may be split
 	-- However, predicates are not treated
 	-- as tycon applications by the type checker
+
+-- XXX - 2006-09-24: This case is hard-coded in (rendering predicates opaque as well)
+--       to make the newly reworked newtype-deriving work on the trivial case:
+--              newtype T = T () deriving (Eq, Ord)
+--       Please remove this if the newtype-deriving scheme no longer produces a PredTy.
+tcSplitTyConApp_maybe (PredTy (ClassP _ [ty']))   = tcSplitTyConApp_maybe ty'
+
 tcSplitTyConApp_maybe other	      	= Nothing
 
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