X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2Ftypecheck%2FTcDeriv.lhs;h=550b274ec501ab8ca3b7d29dc06e5a44ddbf6673;hb=4ea5fe11fbc339a7a1bce13cbb2a2301772b493a;hp=b77796831a97f9d29cb0e078e8a171efcef86b1b;hpb=ad4a18b179fbe4ad314b3accf32e806cf00f2a0b;p=ghc-hetmet.git

diff --git a/compiler/typecheck/TcDeriv.lhs b/compiler/typecheck/TcDeriv.lhs
index b777968..550b274 100644
--- a/compiler/typecheck/TcDeriv.lhs
+++ b/compiler/typecheck/TcDeriv.lhs
@@ -333,8 +333,9 @@ not just use the Num one.  The instance we want is something like:
      instance (Num a, Show (Foo a), Eq (Foo a)) => Num (Foo a) where
      	(+) = ((+)@a)
      	...etc...
-There's no 'corece' needed because after the type checker newtypes
-are transparent.
+There may be a coercion needed which we get from the tycon for the newtype
+when the dict is constructed in TcInstDcls.tcInstDecl2
+
 
 \begin{code}
 makeDerivEqns :: OverlapFlag
@@ -464,7 +465,7 @@ makeDerivEqns overlap_flag tycl_decls
 		-- If there are no tyvars, there's no need
 		-- to abstract over the dictionaries we need
 	dict_tvs = deriv_tvs ++ tc_tvs
-	dict_args | null dict_tvs = []
+	dict_args -- | null dict_tvs = []
 		  | otherwise     = rep_pred : sc_theta
 
 		-- Finally! Here's where we build the dictionary Id