X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2FhsSyn%2FHsPat.lhs;h=87f471788129a863aa9cdd745925449dac66f919;hb=3787d9878e4d62829a555f01b2a4c5866f24f303;hp=842a4f1e51e56bc652ae5ccde6cbc7fb6d23a385;hpb=2eb04ca0f8d0ec72b417cddc60672c696b4a3daa;p=ghc-hetmet.git diff --git a/compiler/hsSyn/HsPat.lhs b/compiler/hsSyn/HsPat.lhs index 842a4f1..87f4717 100644 --- a/compiler/hsSyn/HsPat.lhs +++ b/compiler/hsSyn/HsPat.lhs @@ -5,6 +5,13 @@ \section[PatSyntax]{Abstract Haskell syntax---patterns} \begin{code} +{-# OPTIONS -w #-} +-- The above warning supression flag is a temporary kludge. +-- While working on this module you are encouraged to remove it and fix +-- any warnings in the module. See +-- http://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#Warnings +-- for details + module HsPat ( Pat(..), InPat, OutPat, LPat, @@ -12,7 +19,7 @@ module HsPat ( HsConPatDetails, hsConPatArgs, HsRecFields(..), HsRecField(..), hsRecFields, - mkPrefixConPat, mkCharLitPat, mkNilPat, mkCoPat, + mkPrefixConPat, mkCharLitPat, mkNilPat, mkCoPat, mkCoPatCoI, isBangHsBind, patsAreAllCons, isConPat, isSigPat, isWildPat, @@ -21,8 +28,7 @@ module HsPat ( #include "HsVersions.h" - -import {-# SOURCE #-} HsExpr ( SyntaxExpr ) +import {-# SOURCE #-} HsExpr (SyntaxExpr, LHsExpr, pprLExpr) -- friends: import HsBinds @@ -31,6 +37,7 @@ import HsTypes import HsDoc import BasicTypes -- others: +import Coercion import PprCore ( {- instance OutputableBndr TyVar -} ) import TysWiredIn import Var @@ -60,7 +67,7 @@ data Pat id | LazyPat (LPat id) -- Lazy pattern | AsPat (Located id) (LPat id) -- As pattern | ParPat (LPat id) -- Parenthesised pattern - | BangPat (LPat id) -- Bang patterng + | BangPat (LPat id) -- Bang pattern ------------ Lists, tuples, arrays --------------- | ListPat [LPat id] -- Syntactic list @@ -90,14 +97,22 @@ data Pat id | ConPatOut { pat_con :: Located DataCon, - pat_tvs :: [TyVar], -- Existentially bound type variables - -- including any bound coercion variables - pat_dicts :: [id], -- Ditto dictionaries + pat_tvs :: [TyVar], -- Existentially bound type variables (tyvars only) + pat_dicts :: [id], -- Ditto *coercion variables* and *dictionaries* + -- One reason for putting coercion variable here, I think, + -- is to ensure their kinds are zonked pat_binds :: DictBinds id, -- Bindings involving those dictionaries pat_args :: HsConPatDetails id, pat_ty :: Type -- The type of the pattern } + ------------ View patterns --------------- + | ViewPat (LHsExpr id) + (LPat id) + PostTcType -- The overall type of the pattern + -- (= the argument type of the view function) + -- for hsPatType. + ------------ Literal and n+k patterns --------------- | LitPat HsLit -- Used for *non-overloaded* literal patterns: -- Int#, Char#, Int, Char, String, etc. @@ -106,7 +121,6 @@ data Pat id (Maybe (SyntaxExpr id)) -- Just (Name of 'negate') for negative -- patterns, Nothing otherwise (SyntaxExpr id) -- Equality checker, of type t->t->Bool - PostTcType -- Type of the pattern | NPlusKPat (Located id) -- n+k pattern (HsOverLit id) -- It'll always be an HsIntegral @@ -213,6 +227,7 @@ pprPat (WildPat _) = char '_' pprPat (LazyPat pat) = char '~' <> ppr pat pprPat (BangPat pat) = char '!' <> ppr pat pprPat (AsPat name pat) = parens (hcat [ppr name, char '@', ppr pat]) +pprPat (ViewPat expr pat _) = parens (hcat [pprLExpr expr, text " -> ", ppr pat]) pprPat (ParPat pat) = parens (ppr pat) pprPat (ListPat pats _) = brackets (interpp'SP pats) pprPat (PArrPat pats _) = pabrackets (interpp'SP pats) @@ -229,8 +244,8 @@ pprPat (ConPatOut { pat_con = con, pat_tvs = tvs, pat_dicts = dicts, else pprUserCon con details pprPat (LitPat s) = ppr s -pprPat (NPat l Nothing _ _) = ppr l -pprPat (NPat l (Just _) _ _) = char '-' <> ppr l +pprPat (NPat l Nothing _) = ppr l +pprPat (NPat l (Just _) _) = char '-' <> ppr l pprPat (NPlusKPat n k _ _) = hcat [ppr n, char '+', ppr k] pprPat (TypePat ty) = ptext SLIT("{|") <> ppr ty <> ptext SLIT("|}") pprPat (CoPat co pat _) = parens (pprHsWrapper (ppr pat) co) @@ -286,10 +301,14 @@ mkNilPat ty = mkPrefixConPat nilDataCon [] ty mkCharLitPat :: Char -> OutPat id mkCharLitPat c = mkPrefixConPat charDataCon [noLoc $ LitPat (HsCharPrim c)] charTy -mkCoPat :: HsWrapper -> OutPat id -> Type -> OutPat id -mkCoPat co lpat@(L loc pat) ty - | isIdHsWrapper co = lpat - | otherwise = L loc (CoPat co pat ty) +mkCoPat :: HsWrapper -> Pat id -> Type -> Pat id +mkCoPat co pat ty + | isIdHsWrapper co = pat + | otherwise = CoPat co pat ty + +mkCoPatCoI :: CoercionI -> Pat id -> Type -> Pat id +mkCoPatCoI IdCo pat ty = pat +mkCoPatCoI (ACo co) pat ty = mkCoPat (WpCo co) pat ty \end{code} @@ -346,7 +365,7 @@ patsAreAllLits pat_list = all isLitPat pat_list isLitPat (AsPat _ pat) = isLitPat (unLoc pat) isLitPat (LitPat _) = True -isLitPat (NPat _ _ _ _) = True +isLitPat (NPat _ _ _) = True isLitPat (NPlusKPat _ _ _ _) = True isLitPat other = False @@ -356,7 +375,12 @@ isBangHsBind (PatBind { pat_lhs = L _ (BangPat p) }) = True isBangHsBind bind = False isIrrefutableHsPat :: LPat id -> Bool --- This function returns False if it's in doubt; specifically +-- (isIrrefutableHsPat p) is true if matching against p cannot fail, +-- in the sense of falling through to the next pattern. +-- (NB: this is not quite the same as the (silly) defn +-- in 3.17.2 of the Haskell 98 report.) +-- +-- isIrrefutableHsPat returns False if it's in doubt; specifically -- on a ConPatIn it doesn't know the size of the constructor family -- But if it returns True, the pattern is definitely irrefutable isIrrefutableHsPat pat @@ -372,6 +396,7 @@ isIrrefutableHsPat pat go1 (CoPat _ pat _) = go1 pat go1 (ParPat pat) = go pat go1 (AsPat _ pat) = go pat + go1 (ViewPat _ pat _) = go pat go1 (SigPatIn pat _) = go pat go1 (SigPatOut pat _) = go pat go1 (TuplePat pats _ _) = all go pats @@ -384,7 +409,7 @@ isIrrefutableHsPat pat && all go (hsConPatArgs details) go1 (LitPat _) = False - go1 (NPat _ _ _ _) = False + go1 (NPat _ _ _) = False go1 (NPlusKPat _ _ _ _) = False go1 (TypePat _) = panic "isIrrefutableHsPat: type pattern"