Clean up some comments

  MERGE TO 6.10

diff --git a/compiler/typecheck/TcSimplify.lhs b/compiler/typecheck/TcSimplify.lhs
index 534c5d0..9b192ec 100644 (file)
--- a/compiler/typecheck/TcSimplify.lhs
+++ b/compiler/typecheck/TcSimplify.lhs
@@ -1883,7 +1883,9 @@ reduceContext env wanteds0
                 }
 
           -- Solve the *wanted* *dictionary* constraints (not implications)
-         -- This may expose some further equational constraints...
+         -- This may expose some further equational constraints in the course
+          -- of improvement due to functional dependencies if any of the
+          -- involved unifications gets deferred.
        ; let (wanted_implics, wanted_dicts) = partition isImplicInst wanteds'
        ; (avails, extra_eqs) <- getLIE (reduceList env wanted_dicts init_state)
                   -- The getLIE is reqd because reduceList does improvement

diff --git a/compiler/typecheck/TcTyFuns.lhs b/compiler/typecheck/TcTyFuns.lhs
index 77d7205..2237e3f 100644 (file)
--- a/compiler/typecheck/TcTyFuns.lhs
+++ b/compiler/typecheck/TcTyFuns.lhs
@@ -231,9 +231,6 @@ tcReduceEqs locals wanteds
 We maintain normalised equalities together with the skolems introduced as
 intermediates during flattening of equalities as well as 
 
-!!!TODO: We probably now can do without the skolem set.  It's not used during
-finalisation in the current code.
-
 \begin{code}
 -- |Configuration of normalised equalities used during solving.
 --
@@ -384,9 +381,6 @@ families.  Moreover, in Forms (2) & (3), the left-hand side may not occur in
 the right-hand side, and the relation x > y is an arbitrary, but total order
 on type variables
 
-!!!TODO: We may need to keep track of swapping for error messages (and to
-re-orient on finilisation).
-
 \begin{code}
 data RewriteInst
   = RewriteVar  -- Form (2) above
@@ -960,9 +954,6 @@ applySubstFam eq1@(RewriteFam {rwi_fam = fam1, rwi_args = args1})
     -- rule matches => rewrite
   | fam1 == fam2 && tcEqTypes args1 args2 &&
     (isWantedRewriteInst eq2 || not (isWantedRewriteInst eq1))
--- !!!TODO: tcEqTypes is insufficient as it does not look through type synonyms
--- !!!Check whether anything breaks by making tcEqTypes look through synonyms.
--- !!!Should be ok and we don't want three type equalities.
   = do { co2' <- mkRightTransEqInstCo co2 co1 (lhs, rhs)
        ; eq2' <- deriveEqInst eq2 lhs rhs co2'
        ; liftM Just $ normEqInst eq2'
@@ -1240,7 +1231,7 @@ instantiateAndExtract eqs localsEmpty skolems
       | Just tv2 <- tcGetTyVar_maybe ty2
       , isMetaTyVar tv2
       , mayInst tv2 && (checkingMode || tv2 `elemVarSet` skolems)
-                        -- !!!TODO: this is too liberal, even if tv2 is in 
+                        -- !!!FIXME: this is too liberal, even if tv2 is in 
                         -- skolems we shouldn't instantiate if tvs occurs 
                         -- in other equalities that may propagate it into the
                         -- environment

diff --git a/compiler/types/Type.lhs b/compiler/types/Type.lhs
index 79a561a..07e61da 100644 (file)
--- a/compiler/types/Type.lhs
+++ b/compiler/types/Type.lhs
@@ -1147,14 +1147,16 @@ coreEqType t1 t2
 
 \begin{code}
 tcEqType :: Type -> Type -> Bool
--- ^ Type equality on source types. Does not look through @newtypes@ or 'PredType's
+-- ^ Type equality on source types. Does not look through @newtypes@ or 
+-- 'PredType's, but it does look through type synonyms.
 tcEqType t1 t2 = isEqual $ cmpType t1 t2
 
 tcEqTypes :: [Type] -> [Type] -> Bool
 tcEqTypes tys1 tys2 = isEqual $ cmpTypes tys1 tys2
 
 tcCmpType :: Type -> Type -> Ordering
--- ^ Type ordering on source types. Does not look through @newtypes@ or 'PredType's
+-- ^ Type ordering on source types. Does not look through @newtypes@ or 
+-- 'PredType's, but it does look through type synonyms.
 tcCmpType t1 t2 = cmpType t1 t2
 
 tcCmpTypes :: [Type] -> [Type] -> Ordering