mkPrefixConPat, mkCharLitPat, mkNilPat,
- isWildPat,
- patsAreAllCons, isConPat, isSigPat,
- patsAreAllLits, isLitPat
+ isBangHsBind,
+ patsAreAllCons, isConPat, isSigPat, isWildPat,
+ patsAreAllLits, isLitPat, isIrrefutableHsPat
) where
#include "HsVersions.h"
-import {-# SOURCE #-} HsExpr ( HsExpr )
+import {-# SOURCE #-} HsExpr ( SyntaxExpr )
-- friends:
-import HsBinds ( DictBinds, emptyLHsBinds, pprLHsBinds )
+import HsBinds ( DictBinds, HsBind(..), emptyLHsBinds, pprLHsBinds )
import HsLit ( HsLit(HsCharPrim), HsOverLit )
-import HsTypes ( LHsType, SyntaxName, PostTcType )
+import HsTypes ( LHsType, PostTcType )
import BasicTypes ( Boxity, tupleParens )
-- others:
import PprCore ( {- instance OutputableBndr TyVar -} )
import TysWiredIn ( nilDataCon, charDataCon, charTy )
import Var ( TyVar )
-import DataCon ( DataCon )
+import DataCon ( DataCon, dataConTyCon )
+import TyCon ( isProductTyCon )
import Outputable
import Type ( Type )
import SrcLoc ( Located(..), unLoc, noLoc )
| LazyPat (LPat id) -- Lazy pattern
| AsPat (Located id) (LPat id) -- As pattern
| ParPat (LPat id) -- Parenthesised pattern
+ | BangPat (LPat id) -- Bang patterng
------------ Lists, tuples, arrays ---------------
| ListPat [LPat id] -- Syntactic list
| TuplePat [LPat id] -- Tuple
Boxity -- UnitPat is TuplePat []
+ PostTcType
+ -- You might think that the PostTcType was redundant, but it's essential
+ -- data T a where
+ -- T1 :: Int -> T Int
+ -- f :: (T a, a) -> Int
+ -- f (T1 x, z) = z
+ -- When desugaring, we must generate
+ -- f = /\a. \v::a. case v of (t::T a, w::a) ->
+ -- case t of (T1 (x::Int)) ->
+ -- Note the (w::a), NOT (w::Int), because we have not yet
+ -- refined 'a' to Int. So we must know that the second component
+ -- of the tuple is of type 'a' not Int. See selectMatchVar
| PArrPat [LPat id] -- Syntactic parallel array
PostTcType -- The type of the elements
| ConPatIn (Located id)
(HsConDetails id (LPat id))
- | ConPatOut DataCon
+ | ConPatOut (Located DataCon)
[TyVar] -- Existentially bound type variables
[id] -- Ditto dictionaries
(DictBinds id) -- Bindings involving those dictionaries
| LitPat HsLit -- Used for *non-overloaded* literal patterns:
-- Int#, Char#, Int, Char, String, etc.
- | NPatIn HsOverLit -- Always positive
- (Maybe SyntaxName) -- Just (Name of 'negate') for negative
- -- patterns, Nothing otherwise
-
- | NPatOut HsLit -- Used for literal patterns where there's an equality function to call
- -- The literal is retained so that the desugarer can readily identify
- -- equations with identical literal-patterns
- -- Always HsInteger, HsRat or HsString.
- -- *Unlike* NPatIn, for negative literals, the
- -- literal is acutally negative!
- Type -- Type of pattern, t
- (HsExpr id) -- Of type t -> Bool; detects match
-
- | NPlusKPatIn (Located id) -- n+k pattern
- HsOverLit -- It'll always be an HsIntegral
- SyntaxName -- Name of '-' (see RnEnv.lookupSyntaxName)
-
- | NPlusKPatOut (Located id)
- Integer
- (HsExpr id) -- Of type t -> Bool; detects match
- (HsExpr id) -- Of type t -> t; subtracts k
+ | NPat (HsOverLit id) -- ALWAYS positive
+ (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
+ (SyntaxExpr id) -- (>=) function, of type t->t->Bool
+ (SyntaxExpr id) -- Name of '-' (see RnEnv.lookupSyntaxName)
------------ Generics ---------------
| TypePat (LHsType id) -- Type pattern for generic definitions
ppr var
pprPat :: (OutputableBndr name) => Pat name -> SDoc
-
pprPat (VarPat var) = pprPatBndr var
pprPat (VarPatOut var bs) = parens (pprPatBndr var <+> braces (ppr bs))
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 (ParPat pat) = parens (ppr pat)
-
-pprPat (ListPat pats _) = brackets (interpp'SP pats)
-pprPat (PArrPat pats _) = pabrackets (interpp'SP pats)
-pprPat (TuplePat pats bx) = tupleParens bx (interpp'SP pats)
+pprPat (ListPat pats _) = brackets (interpp'SP pats)
+pprPat (PArrPat pats _) = pabrackets (interpp'SP pats)
+pprPat (TuplePat pats bx _) = tupleParens bx (interpp'SP pats)
pprPat (ConPatIn con details) = pprUserCon con details
pprPat (ConPatOut con tvs dicts binds details _)
else pprUserCon con details
pprPat (LitPat s) = ppr s
-pprPat (NPatIn l _) = ppr l
-pprPat (NPatOut l _ _) = ppr l
-pprPat (NPlusKPatIn n k _) = hcat [ppr n, char '+', ppr k]
-pprPat (NPlusKPatOut n k _ _) = hcat [ppr n, char '+', integer k]
+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 (SigPatIn pat ty) = ppr pat <+> dcolon <+> ppr ty
pprPat (SigPatOut pat ty) = ppr pat <+> dcolon <+> ppr ty
\begin{code}
mkPrefixConPat :: DataCon -> [OutPat id] -> Type -> OutPat id
-- Make a vanilla Prefix constructor pattern
-mkPrefixConPat dc pats ty = noLoc $ ConPatOut dc [] [] emptyLHsBinds (PrefixCon pats) ty
+mkPrefixConPat dc pats ty = noLoc $ ConPatOut (noLoc dc) [] [] emptyLHsBinds (PrefixCon pats) ty
mkNilPat :: Type -> OutPat id
mkNilPat ty = mkPrefixConPat nilDataCon [] ty
isConPat (ConPatOut _ _ _ _ _ _) = True
isConPat (ListPat _ _) = True
isConPat (PArrPat _ _) = True
-isConPat (TuplePat _ _) = True
+isConPat (TuplePat _ _ _) = True
isConPat (DictPat ds ms) = (length ds + length ms) > 1
isConPat other = False
isLitPat (AsPat _ pat) = isLitPat (unLoc pat)
isLitPat (LitPat _) = True
-isLitPat (NPatIn _ _) = True
-isLitPat (NPatOut _ _ _) = True
-isLitPat (NPlusKPatIn _ _ _) = True
-isLitPat (NPlusKPatOut _ _ _ _) = True
+isLitPat (NPat _ _ _ _) = True
+isLitPat (NPlusKPat _ _ _ _) = True
isLitPat other = 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
+-- 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
+ = go pat
+ where
+ go (L _ pat) = go1 pat
+
+ go1 (WildPat _) = True
+ go1 (VarPat _) = True
+ go1 (VarPatOut _ _) = True
+ go1 (LazyPat pat) = True
+ go1 (BangPat pat) = go pat
+ go1 (ParPat pat) = go pat
+ go1 (AsPat _ 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 (ConPatIn _ _) = False -- Conservative
+ go1 (ConPatOut (L _ con) _ _ _ details _)
+ = isProductTyCon (dataConTyCon con)
+ && all go (hsConArgs details)
+
+ go1 (LitPat _) = False
+ go1 (NPat _ _ _ _) = False
+ go1 (NPlusKPat _ _ _ _) = False
+
+ go1 (TypePat _) = panic "isIrrefutableHsPat: type pattern"
+ go1 (DictPat _ _) = panic "isIrrefutableHsPat: type pattern"
\end{code}
projects / ghc-hetmet.git / blobdiff