-- any warnings in the module. See
-- http://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#Warnings
-- for details
+{-# LANGUAGE DeriveDataTypeable #-}
module HsPat (
Pat(..), InPat, OutPat, LPat,
HsConPatDetails, hsConPatArgs,
HsRecFields(..), HsRecField(..), hsRecFields,
- mkPrefixConPat, mkCharLitPat, mkNilPat, mkCoPat, mkCoPatCoI,
+ mkPrefixConPat, mkCharLitPat, mkNilPat,
- isBangHsBind, hsPatNeedsParens,
- patsAreAllCons, isConPat, isSigPat, isWildPat,
- patsAreAllLits, isLitPat, isIrrefutableHsPat,
+ isBangHsBind, isBangLPat, hsPatNeedsParens,
+ isIrrefutableHsPat,
pprParendLPat
) where
import HsTypes
import BasicTypes
-- others:
-import Coercion
import PprCore ( {- instance OutputableBndr TyVar -} )
import TysWiredIn
import Var
import Type
import SrcLoc
import FastString
+-- libraries:
+import Data.Data hiding (TyCon)
+import Data.Maybe
\end{code}
-- support hsPatType :: Pat Id -> Type
| VarPat id -- Variable
- | VarPatOut id (DictBinds id) -- Used only for overloaded Ids; the
+ | VarPatOut id TcEvBinds -- Used only for overloaded Ids; the
-- bindings give its overloaded instances
| LazyPat (LPat id) -- Lazy pattern
| AsPat (Located id) (LPat id) -- As pattern
| ConPatOut {
pat_con :: Located DataCon,
pat_tvs :: [TyVar], -- Existentially bound type variables (tyvars only)
- pat_dicts :: [id], -- Ditto *coercion variables* and *dictionaries*
+ pat_dicts :: [EvVar], -- 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_binds :: TcEvBinds, -- Bindings involving those dictionaries
pat_args :: HsConPatDetails id,
pat_ty :: Type -- The type of the pattern
}
Type
------------ Pattern coercions (translation only) ---------------
- | CoPat HsWrapper -- If co::t1 -> t2, p::t2,
+ | CoPat HsWrapper -- If co :: t1 ~ t2, p :: t2,
-- then (CoPat co p) :: t1
(Pat id) -- Why not LPat? Ans: existing locn will do
Type -- Type of whole pattern, t1
-- During desugaring a (CoPat co pat) turns into a cast with 'co' on
-- the scrutinee, followed by a match on 'pat'
+ deriving (Data, Typeable)
\end{code}
HsConDetails is use for patterns/expressions *and* for data type declarations
= PrefixCon [arg] -- C p1 p2 p3
| RecCon rec -- C { x = p1, y = p2 }
| InfixCon arg arg -- p1 `C` p2
+ deriving (Data, Typeable)
type HsConPatDetails id = HsConDetails (LPat id) (HsRecFields id (LPat id))
-- Used for both expressions and patterns
= HsRecFields { rec_flds :: [HsRecField id arg],
rec_dotdot :: Maybe Int } -- Note [DotDot fields]
+ deriving (Data, Typeable)
-- Note [DotDot fields]
-- ~~~~~~~~~~~~~~~~~~~~
data HsRecField id arg = HsRecField {
hsRecFieldId :: Located id,
- hsRecFieldArg :: arg,
+ hsRecFieldArg :: arg, -- Filled in by renamer
hsRecPun :: Bool -- Note [Punning]
- }
+ } deriving (Data, Typeable)
-- Note [Punning]
-- ~~~~~~~~~~~~~~
if debugStyle sty then -- typechecked Pat in an error message,
-- and we want to make sure it prints nicely
ppr con <+> sep [ hsep (map pprPatBndr tvs) <+> hsep (map pprPatBndr dicts),
- pprLHsBinds binds, pprConArgs details]
+ ppr binds, pprConArgs details]
else pprUserCon con details
pprPat (LitPat s) = ppr s
-- Make a vanilla Prefix constructor pattern
mkPrefixConPat dc pats ty
= noLoc $ ConPatOut { pat_con = noLoc dc, pat_tvs = [], pat_dicts = [],
- pat_binds = emptyLHsBinds, pat_args = PrefixCon pats,
+ pat_binds = emptyTcEvBinds, pat_args = PrefixCon pats,
pat_ty = ty }
mkNilPat :: Type -> OutPat id
mkCharLitPat :: Char -> OutPat id
mkCharLitPat c = mkPrefixConPat charDataCon [noLoc $ LitPat (HsCharPrim c)] charTy
-
-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 _ = 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 _ = 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 _ = False
-
-isSigPat :: Pat id -> Bool
-isSigPat (SigPatIn _ _) = True
-isSigPat (SigPatOut _ _) = True
-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 (NPlusKPat _ _ _ _) = True
-isLitPat _ = False
+isBangLPat :: LPat id -> Bool
+isBangLPat (L _ (BangPat {})) = True
+isBangLPat (L _ (ParPat p)) = isBangLPat p
+isBangLPat _ = False
isBangHsBind :: HsBind id -> Bool
-- In this module because HsPat is above HsBinds in the import graph
-isBangHsBind (PatBind { pat_lhs = L _ (BangPat _) }) = True
-isBangHsBind _ = False
+isBangHsBind (PatBind { pat_lhs = p }) = isBangLPat p
+isBangHsBind _ = False
isIrrefutableHsPat :: OutputableBndr id => LPat id -> Bool
-- (isIrrefutableHsPat p) is true if matching against p cannot fail,
go1 (ConPatIn {}) = False -- Conservative
go1 (ConPatOut{ pat_con = L _ con, pat_args = details })
- = isProductTyCon (dataConTyCon con)
+ = isJust (tyConSingleDataCon_maybe (dataConTyCon con))
+ -- NB: tyConSingleDataCon_maybe, *not* isProductTyCon, because
+ -- the latter is false of existentials. See Trac #4439
&& all go (hsConPatArgs details)
go1 (LitPat {}) = False
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