\section[PatSyntax]{Abstract Haskell syntax---patterns}
\begin{code}
-{-# OPTIONS -w #-}
+{-# OPTIONS -fno-warn-incomplete-patterns #-}
-- 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
HsConPatDetails, hsConPatArgs,
HsRecFields(..), HsRecField(..), hsRecFields,
+ HsQuasiQuote(..),
+
mkPrefixConPat, mkCharLitPat, mkNilPat, mkCoPat, mkCoPatCoI,
isBangHsBind,
patsAreAllLits, isLitPat, isIrrefutableHsPat
) where
-#include "HsVersions.h"
-
-
-import {-# SOURCE #-} HsExpr ( SyntaxExpr )
+import {-# SOURCE #-} HsExpr (SyntaxExpr, LHsExpr, pprLExpr)
-- friends:
import HsBinds
import Outputable
import Type
import SrcLoc
+import FastString
\end{code}
| 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
| 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.
+
+ ------------ Quasiquoted patterns ---------------
+ -- See Note [Quasi-quote overview] in TcSplice
+ | QuasiQuotePat (HsQuasiQuote id)
+
------------ Literal and n+k patterns ---------------
| LitPat HsLit -- Used for *non-overloaded* literal patterns:
-- Int#, Char#, Int, Char, String, etc.
(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
hsRecFields rbinds = map (unLoc . hsRecFieldId) (rec_flds rbinds)
\end{code}
+\begin{code}
+data HsQuasiQuote id = HsQuasiQuote
+ id
+ id
+ SrcSpan
+ FastString
+
+instance OutputableBndr id => Outputable (HsQuasiQuote id) where
+ ppr = ppr_qq
+
+ppr_qq :: OutputableBndr id => HsQuasiQuote id -> SDoc
+ppr_qq (HsQuasiQuote name quoter _ quote) =
+ char '$' <> brackets (ppr name) <>
+ ptext (sLit "[:") <> ppr quoter <> ptext (sLit "|") <>
+ ppr quote <> ptext (sLit "|]")
+\end{code}
+
%************************************************************************
%* *
pprPat (LazyPat pat) = char '~' <> ppr pat
pprPat (BangPat pat) = char '!' <> ppr pat
pprPat (AsPat name pat) = parens (hcat [ppr name, char '@', ppr pat])
+pprPat (ViewPat expr pat _) = parens (hcat [pprLExpr expr, text " -> ", ppr pat])
pprPat (ParPat pat) = parens (ppr pat)
pprPat (ListPat pats _) = brackets (interpp'SP pats)
pprPat (PArrPat pats _) = pabrackets (interpp'SP pats)
else pprUserCon con details
pprPat (LitPat s) = ppr s
-pprPat (NPat l Nothing _ _) = ppr l
-pprPat (NPat l (Just _) _ _) = char '-' <> ppr l
+pprPat (NPat l Nothing _) = ppr l
+pprPat (NPat l (Just _) _) = char '-' <> ppr l
pprPat (NPlusKPat n k _ _) = hcat [ppr n, char '+', ppr k]
-pprPat (TypePat ty) = ptext SLIT("{|") <> ppr ty <> ptext SLIT("|}")
+pprPat (QuasiQuotePat (HsQuasiQuote name quoter _ quote))
+ = char '$' <> brackets (ppr name) <>
+ ptext (sLit "[:") <> ppr quoter <> ptext (sLit "|") <>
+ ppr quote <> ptext (sLit "|]")
+pprPat (TypePat ty) = ptext (sLit "{|") <> ppr ty <> ptext (sLit "|}")
pprPat (CoPat co pat _) = parens (pprHsWrapper (ppr pat) co)
pprPat (SigPatIn pat ty) = ppr pat <+> dcolon <+> ppr ty
pprPat (SigPatOut pat ty) = ppr pat <+> dcolon <+> ppr ty
+pprUserCon :: (Outputable con, OutputableBndr id) => con -> HsConPatDetails id -> SDoc
pprUserCon c (InfixCon p1 p2) = ppr p1 <+> ppr c <+> ppr p2
pprUserCon c details = ppr c <+> pprConArgs details
+pprConArgs :: OutputableBndr id => HsConPatDetails id -> SDoc
pprConArgs (PrefixCon pats) = interppSP pats
pprConArgs (InfixCon p1 p2) = interppSP [p1,p2]
pprConArgs (RecCon rpats) = ppr rpats
ppr (HsRecFields { rec_flds = flds, rec_dotdot = Just n })
= braces (fsep (punctuate comma (map ppr (take n flds) ++ [dotdot])))
where
- dotdot = ptext SLIT("..") <+> ifPprDebug (ppr (drop n flds))
+ dotdot = ptext (sLit "..") <+> ifPprDebug (ppr (drop n flds))
instance (OutputableBndr id, Outputable arg)
=> Outputable (HsRecField id arg) where
-- add parallel array brackets around a document
--
pabrackets :: SDoc -> SDoc
-pabrackets p = ptext SLIT("[:") <> p <> ptext SLIT(":]")
+pabrackets p = ptext (sLit "[:") <> p <> ptext (sLit ":]")
\end{code}
| 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
+mkCoPatCoI IdCo pat _ = pat
+mkCoPatCoI (ACo co) pat ty = mkCoPat (WpCast co) pat ty
\end{code}
The 1.3 report defines what ``irrefutable'' and ``failure-free'' patterns are.
\begin{code}
+isWildPat :: Pat id -> Bool
isWildPat (WildPat _) = True
-isWildPat other = False
+isWildPat _ = False
patsAreAllCons :: [Pat id] -> Bool
patsAreAllCons pat_list = all isConPat pat_list
+isConPat :: Pat id -> Bool
isConPat (AsPat _ pat) = isConPat (unLoc pat)
isConPat (ConPatIn {}) = True
isConPat (ConPatOut {}) = True
isConPat (ListPat {}) = True
isConPat (PArrPat {}) = True
isConPat (TuplePat {}) = True
-isConPat other = False
+isConPat _ = False
+isSigPat :: Pat id -> Bool
isSigPat (SigPatIn _ _) = True
isSigPat (SigPatOut _ _) = True
-isSigPat other = False
+isSigPat _ = False
patsAreAllLits :: [Pat id] -> Bool
patsAreAllLits pat_list = all isLitPat pat_list
+isLitPat :: Pat id -> Bool
isLitPat (AsPat _ pat) = isLitPat (unLoc pat)
isLitPat (LitPat _) = True
-isLitPat (NPat _ _ _ _) = True
+isLitPat (NPat _ _ _) = True
isLitPat (NPlusKPat _ _ _ _) = True
-isLitPat other = False
+isLitPat _ = False
isBangHsBind :: HsBind id -> Bool
-- In this module because HsPat is above HsBinds in the import graph
-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
+isBangHsBind (PatBind { pat_lhs = L _ (BangPat _) }) = True
+isBangHsBind _ = False
+
+isIrrefutableHsPat :: OutputableBndr id => LPat id -> Bool
+-- (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
go1 (WildPat _) = True
go1 (VarPat _) = True
go1 (VarPatOut _ _) = True
- go1 (LazyPat pat) = True
+ go1 (LazyPat _) = True
go1 (BangPat pat) = go 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
- go1 (ListPat pats _) = False
- go1 (PArrPat pats _) = False -- ?
+ go1 (ListPat _ _) = False
+ go1 (PArrPat _ _) = False -- ?
go1 (ConPatIn _ _) = False -- Conservative
go1 (ConPatOut{ pat_con = L _ con, pat_args = details })
&& all go (hsConPatArgs details)
go1 (LitPat _) = False
- go1 (NPat _ _ _ _) = False
+ go1 (NPat _ _ _) = False
go1 (NPlusKPat _ _ _ _) = False
- go1 (TypePat _) = panic "isIrrefutableHsPat: type pattern"
+ go1 (QuasiQuotePat {}) = urk pat -- Gotten rid of by renamer, before
+ -- isIrrefutablePat is called
+ go1 (TypePat {}) = urk pat
+
+ urk pat = pprPanic "isIrrefutableHsPat:" (ppr pat)
\end{code}
projects / ghc-hetmet.git / blobdiff