X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2Ftypecheck%2FTcInstDcls.lhs;h=e7c472b4751cbf3d863b209687da1596e0256eea;hp=466cee9d25aa130a121976a046b6d6832ea9313a;hb=e79c9ce01d0ce4412bd4bcd99c8c728a6a2ec569;hpb=62ee856ca84f409741f472ce3527d6deafa5b62a

diff --git a/compiler/typecheck/TcInstDcls.lhs b/compiler/typecheck/TcInstDcls.lhs
index 466cee9..e7c472b 100644
--- a/compiler/typecheck/TcInstDcls.lhs
+++ b/compiler/typecheck/TcInstDcls.lhs
@@ -96,9 +96,9 @@ Running example:
 	op1_i = /\a. \(d:C a). 
 	       let this :: C [a]
 		   this = df_i a d
+	             -- Note [Subtle interaction of recursion and overlap]
 
 		   local_op1 :: forall b. Ix b => [a] -> b -> b
-	             -- Note [Subtle interaction of recursion and overlap]
 	           local_op1 = <rhs>
 	       	     -- Source code; run the type checker on this
 		     -- NB: Type variable 'a' (but not 'b') is in scope in <rhs>
@@ -571,7 +571,7 @@ tcInstDecl2 :: InstInfo Name -> TcM (LHsBinds Id)
 --      newtype N a = MkN (Tree [a]) deriving( Foo Int )
 --
 -- The newtype gives an FC axiom looking like
---      axiom CoN a ::  N a :=: Tree [a]
+--      axiom CoN a ::  N a ~ Tree [a]
 --   (see Note [Newtype coercions] in TyCon for this unusual form of axiom)
 --
 -- So all need is to generate a binding looking like:
@@ -614,9 +614,10 @@ tcInstDecl2 (InstInfo { iSpec = ispec, iBinds = NewTypeDerived })
 
         -- Figure out bindings for the superclass context from dfun_dicts
         -- Don't include this_dict in the 'givens', else
-        -- sc_dicst get bound by just selecting from this_dict!!
+        -- sc_dicts get bound by just selecting from this_dict!!
         ; sc_binds <- addErrCtxt superClassCtxt $
-                      tcSimplifySuperClasses inst_loc dfun_dicts (rep_dict:sc_dicts)
+                      tcSimplifySuperClasses inst_loc this_dict dfun_dicts 
+					     (rep_dict:sc_dicts)
 
 	-- It's possible that the superclass stuff might unified something
 	-- in the envt with one of the clas_tyvars
@@ -636,7 +637,7 @@ tcInstDecl2 (InstInfo { iSpec = ispec, iBinds = NewTypeDerived })
       --        make_coercion
       -- The inst_head looks like (C s1 .. sm (T a1 .. ak))
       -- But we want the coercion (C s1 .. sm (sym (CoT a1 .. ak)))
-      --        with kind (C s1 .. sm (T a1 .. ak)  :=:  C s1 .. sm <rep_ty>)
+      --        with kind (C s1 .. sm (T a1 .. ak)  ~  C s1 .. sm <rep_ty>)
       --        where rep_ty is the (eta-reduced) type rep of T
       -- So we just replace T with CoT, and insert a 'sym'
       -- NB: we know that k will be >= arity of CoT, because the latter fully eta-reduced
@@ -735,7 +736,7 @@ tcInstDecl2 (InstInfo { iSpec = ispec, iBinds = VanillaInst monobinds uprags })
     -- Don't include this_dict in the 'givens', else
     -- sc_dicts get bound by just selecting  from this_dict!!
     sc_binds <- addErrCtxt superClassCtxt $
-                tcSimplifySuperClasses inst_loc dfun_dicts sc_dicts
+                tcSimplifySuperClasses inst_loc this_dict dfun_dicts sc_dicts
 		-- Note [Recursive superclasses]
 
 	-- It's possible that the superclass stuff might unified something