Fix haddock markup

[ghc-hetmet.git] / compiler / typecheck / TcCanonical.lhs

diff --git a/compiler/typecheck/TcCanonical.lhs b/compiler/typecheck/TcCanonical.lhs
index 2331d2d..42c2515 100644 (file)
--- a/compiler/typecheck/TcCanonical.lhs
+++ b/compiler/typecheck/TcCanonical.lhs
@@ -497,10 +497,10 @@ inert set is an idempotent subustitution...
 
 \begin{code}
 data TypeClassifier 
-  = FskCls TcTyVar      -- Flatten skolem 
-  | VarCls TcTyVar     -- *Non-flatten-skolem* variable 
-  | FunCls TyCon [Type]        -- Type function, exactly saturated
-  | OtherCls TcType    -- Neither of the above
+  = FskCls TcTyVar      -- ^ Flatten skolem 
+  | VarCls TcTyVar      -- ^ *Non-flatten-skolem* variable 
+  | FunCls TyCon [Type] -- ^ Type function, exactly saturated
+  | OtherCls TcType     -- ^ Neither of the above
 
 unClassify :: TypeClassifier -> TcType
 unClassify (VarCls tv)      = TyVarTy tv
@@ -541,15 +541,19 @@ reOrient _untch (FunCls {})   (VarCls tv2)  = isMetaTyVar tv2
 reOrient _untch (FunCls {}) _               = False             -- Fun/Other on rhs
 
 reOrient _untch (VarCls tv1) (FunCls {})    = not $ isMetaTyVar tv1
+        -- Put function on the left, *except* if the RHS becomes
+        -- a meta-tyvar; see invariant on CFunEqCan 
+        -- and Note [No touchables as FunEq RHS]
 
-reOrient _untch (VarCls tv1)  (FskCls {})   = not $ isMetaTyVar tv1
-      -- See Note [Loopy Spontaneous Solving, Example 4]
+reOrient _untch (VarCls tv1) (FskCls {})    = not $ isMetaTyVar tv1
+   -- Put flatten-skolems on the left if possible:
+   --   see Note [Loopy Spontaneous Solving, Example 4] in TcInteract
 
 reOrient _untch (VarCls {})  (OtherCls {})  = False
 reOrient _untch (VarCls {})  (VarCls {})    = False
 
 reOrient _untch (FskCls {}) (VarCls tv2)    = isMetaTyVar tv2 
-      -- See Note [Loopy Spontaneous Solving, Example 4]
+      -- See Note [Loopy Spontaneous Solving, Example 4] in TcInteract
 
 reOrient _untch (FskCls {}) (FskCls {})     = False
 reOrient _untch (FskCls {}) (FunCls {})     = True