Use FractionalLit more extensively to improve other pretty printers

[ghc-hetmet.git] / compiler / deSugar / Check.lhs

diff --git a/compiler/deSugar/Check.lhs b/compiler/deSugar/Check.lhs
index 355055b..d9aefbe 100644 (file)
--- a/compiler/deSugar/Check.lhs
+++ b/compiler/deSugar/Check.lhs
@@ -27,10 +27,10 @@ import TysWiredIn
 import PrelNames
 import TyCon
 import Type
-import Unify( dataConCannotMatch )
 import SrcLoc
 import UniqSet
 import Util
+import BasicTypes
 import Outputable
 import FastString
 \end{code}
@@ -112,7 +112,8 @@ check :: [EquationInfo] -> ([ExhaustivePat], [EquationInfo])
   -- if there are view patterns, just give up - don't know what the function is
 check qs = (untidy_warns, shadowed_eqns)
       where
-       (warns, used_nos) = check' ([1..] `zip` map tidy_eqn qs)
+        tidy_qs = map tidy_eqn qs
+       (warns, used_nos) = check' ([1..] `zip` tidy_qs)
        untidy_warns = map untidy_exhaustive warns 
        shadowed_eqns = [eqn | (eqn,i) <- qs `zip` [1..], 
                                not (i `elementOfUniqSet` used_nos)]
@@ -436,14 +437,14 @@ get_lit :: Pat id -> Maybe HsLit
 -- It doesn't matter which one, because they will only be compared
 -- with other HsLits gotten in the same way
 get_lit (LitPat lit)                                     = Just lit
-get_lit (NPat (OverLit { ol_val = HsIntegral i})    mb _) = Just (HsIntPrim   (mb_neg mb i))
-get_lit (NPat (OverLit { ol_val = HsFractional f }) mb _) = Just (HsFloatPrim (mb_neg mb f))
+get_lit (NPat (OverLit { ol_val = HsIntegral i})    mb _) = Just (HsIntPrim   (mb_neg negate              mb i))
+get_lit (NPat (OverLit { ol_val = HsFractional f }) mb _) = Just (HsFloatPrim (mb_neg negateFractionalLit mb f))
 get_lit (NPat (OverLit { ol_val = HsIsString s })   _  _) = Just (HsStringPrim s)
 get_lit _                                                = Nothing
 
-mb_neg :: Num a => Maybe b -> a -> a
-mb_neg Nothing  v = v
-mb_neg (Just _) v = -v
+mb_neg :: (a -> a) -> Maybe b -> a -> a
+mb_neg _      Nothing  v = v
+mb_neg negate (Just _) v = negate v
 
 get_unused_cons :: [Pat Id] -> [DataCon]
 get_unused_cons used_cons = ASSERT( not (null used_cons) ) unused_cons
@@ -643,7 +644,7 @@ might_fail_pat (ConPatOut { pat_args = ps }) = any might_fail_lpat (hsConPatArgs
 
 -- Finally the ones that are sure to succeed, or which are covered by the checking algorithm
 might_fail_pat (LazyPat _)                   = False -- Always succeeds
-might_fail_pat _                             = False -- VarPat, VarPatOut, WildPat, LitPat, NPat, TypePat
+might_fail_pat _                             = False -- VarPat, WildPat, LitPat, NPat, TypePat
 
 --------------
 might_fail_lpat :: LPat Id -> Bool
@@ -657,7 +658,6 @@ tidy_lpat p = fmap tidy_pat p
 tidy_pat :: Pat Id -> Pat Id
 tidy_pat pat@(WildPat _)  = pat
 tidy_pat (VarPat id)      = WildPat (idType id) 
-tidy_pat (VarPatOut id _) = WildPat (idType id)        -- Ignore the bindings
 tidy_pat (ParPat p)       = tidy_pat (unLoc p)
 tidy_pat (LazyPat p)      = WildPat (hsLPatType p)     -- For overlap and exhaustiveness checking
                                                        -- purposes, a ~pat is like a wildcard
@@ -672,8 +672,6 @@ tidy_pat (CoPat _ pat _)  = tidy_pat pat
 tidy_pat (NPlusKPat id _ _ _) = WildPat (idType (unLoc id))
 tidy_pat (ViewPat _ _ ty)     = WildPat ty
 
-tidy_pat (NPat lit mb_neg eq) = tidyNPat lit mb_neg eq
-
 tidy_pat pat@(ConPatOut { pat_con = L _ id, pat_args = ps })
   = pat { pat_args = tidy_con id ps }
 
@@ -697,16 +695,18 @@ tidy_pat (TuplePat ps boxity ty)
   where
     arity = length ps
 
--- Unpack string patterns fully, so we can see when they overlap with
--- each other, or even explicit lists of Chars.
-tidy_pat (LitPat lit)
+tidy_pat (NPat lit mb_neg eq) = tidyNPat tidy_lit_pat lit mb_neg eq
+tidy_pat (LitPat lit)         = tidy_lit_pat lit
+
+tidy_lit_pat :: HsLit -> Pat Id
+-- Unpack string patterns fully, so we can see when they 
+-- overlap with each other, or even explicit lists of Chars.
+tidy_lit_pat lit
   | HsString s <- lit
-  = unLoc $ foldr (\c pat -> mkPrefixConPat consDataCon [mk_char_lit c, pat] stringTy)
+  = unLoc $ foldr (\c pat -> mkPrefixConPat consDataCon [mkCharLitPat c, pat] stringTy)
                  (mkPrefixConPat nilDataCon [] stringTy) (unpackFS s)
   | otherwise
   = tidyLitPat lit 
-  where
-    mk_char_lit c = mkPrefixConPat charDataCon [nlLitPat (HsCharPrim c)] charTy
 
 -----------------
 tidy_con :: DataCon -> HsConPatDetails Id -> HsConPatDetails Id