\begin{code}
module HsPat (
- Pat(..), InPat, OutPat,
+ Pat(..), InPat, OutPat, LPat,
HsConDetails(..), hsConArgs,
- mkPrefixConPat, mkCharLitPat, mkNilPat,
+ mkPrefixConPat, mkCharLitPat, mkNilPat,
- failureFreePat, isWildPat,
- patsAreAllCons, isConPat, isSigPat,
- patsAreAllLits, isLitPat,
- collectPatBinders, collectPatsBinders,
- collectSigTysFromPat, collectSigTysFromPats
+ isBangHsBind,
+ patsAreAllCons, isConPat, isSigPat, isWildPat,
+ patsAreAllLits, isLitPat, isIrrefutableHsPat
) where
#include "HsVersions.h"
-import {-# SOURCE #-} HsExpr ( HsExpr )
+import {-# SOURCE #-} HsExpr ( SyntaxExpr )
-- friends:
+import HsBinds ( DictBinds, HsBind(..), emptyLHsBinds, pprLHsBinds )
import HsLit ( HsLit(HsCharPrim), HsOverLit )
-import HsTypes ( HsType, 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, dataConTyCon )
-import Maybes ( maybeToBool )
+import TyCon ( isProductTyCon )
import Outputable
-import TyCon ( maybeTyConSingleCon )
import Type ( Type )
+import SrcLoc ( Located(..), unLoc, noLoc )
\end{code}
\begin{code}
-type InPat id = Pat id -- No 'Out' constructors
-type OutPat id = Pat id -- No 'In' constructors
+type InPat id = LPat id -- No 'Out' constructors
+type OutPat id = LPat id -- No 'In' constructors
+
+type LPat id = Located (Pat id)
data Pat id
= ------------ Simple patterns ---------------
WildPat PostTcType -- Wild card
| VarPat id -- Variable
- | LazyPat (Pat id) -- Lazy pattern
- | AsPat id (Pat id) -- As pattern
- | ParPat (Pat id) -- Parenthesised pattern
+ | VarPatOut id (DictBinds id) -- Used only for overloaded Ids; the
+ -- bindings give its overloaded instances
+ | 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 [Pat id] -- Syntactic list
+ | ListPat [LPat id] -- Syntactic list
PostTcType -- The type of the elements
- | TuplePat [Pat id] -- Tuple
+ | TuplePat [LPat id] -- Tuple
Boxity -- UnitPat is TuplePat []
-
- | PArrPat [Pat id] -- Syntactic parallel array
+ 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
------------ Constructor patterns ---------------
- | ConPatIn id
- (HsConDetails id (Pat id))
+ | ConPatIn (Located id)
+ (HsConDetails id (LPat id))
- | ConPatOut DataCon
- (HsConDetails id (Pat id))
- Type -- The type of the pattern
+ | ConPatOut (Located DataCon)
[TyVar] -- Existentially bound type variables
[id] -- Ditto dictionaries
+ (DictBinds id) -- Bindings involving those dictionaries
+ (HsConDetails id (LPat id))
+ Type -- The type of the pattern
------------ Literal and n+k patterns ---------------
| 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.
- -- 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 id -- n+k pattern
- HsOverLit -- It'll always be an HsIntegral
- SyntaxName -- Name of '-' (see RnEnv.lookupSyntaxName)
-
- | NPlusKPatOut 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 (HsType id) -- Type pattern for generic definitions
+ | TypePat (LHsType id) -- Type pattern for generic definitions
-- e.g f{| a+b |} = ...
-- These show up only in class declarations,
-- and should be a top-level pattern
------------ Pattern type signatures ---------------
- | SigPatIn (Pat id) -- Pattern with a type signature
- (HsType id)
+ | SigPatIn (LPat id) -- Pattern with a type signature
+ (LHsType id)
- | SigPatOut (Pat id) -- Pattern p
- Type -- Type, t, of the whole pattern
- (HsExpr id) -- Coercion function,
- -- of type t -> typeof(p)
+ | SigPatOut (LPat id) -- Pattern with a type signature
+ Type
------------ Dictionary patterns (translation only) ---------------
| DictPat -- Used when destructing Dictionaries with an explicit case
\begin{code}
data HsConDetails id arg
= PrefixCon [arg] -- C p1 p2 p3
- | RecCon [(id, arg)] -- C { x = p1, y = p2 }
+ | RecCon [(Located id, arg)] -- C { x = p1, y = p2 }
| InfixCon arg arg -- p1 `C` p2
hsConArgs :: HsConDetails id arg -> [arg]
instance (OutputableBndr name) => Outputable (Pat name) where
ppr = pprPat
-pprPat :: (OutputableBndr name) => Pat name -> SDoc
-
-pprPat (VarPat var) -- Print with type info if -dppr-debug is on
+pprPatBndr :: OutputableBndr name => name -> SDoc
+pprPatBndr var -- Print with type info if -dppr-debug is on
= getPprStyle $ \ sty ->
if debugStyle sty then
parens (pprBndr LambdaBind var) -- Could pass the site to pprPat
else
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 (pprPat 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 (ConPatIn c details) = pprConPat c details
-pprPat (ConPatOut c details _ _ _) = pprConPat c details
+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 (ConPatIn con details) = pprUserCon con details
+pprPat (ConPatOut con tvs dicts binds details _)
+ = getPprStyle $ \ sty -> -- Tiresome; in TcBinds.tcRhs we print out a
+ 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]
+ 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 (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
-
-pprPat (DictPat dicts methods)
- = parens (sep [ptext SLIT("{-dict-}"),
- brackets (interpp'SP dicts),
- brackets (interpp'SP methods)])
-
-
-
-pprConPat con (PrefixCon pats) = ppr con <+> interppSP pats -- inner ParPats supply the necessary parens.
-pprConPat con (InfixCon pat1 pat2) = hsep [ppr pat1, ppr con, ppr pat2] -- ParPats put in parens
- -- ToDo: use pprSym to print op (but this involves fiddling various
- -- contexts & I'm lazy...); *PatIns are *rarely* printed anyway... (WDP)
-pprConPat con (RecCon rpats)
- = ppr con <+> braces (hsep (punctuate comma (map (pp_rpat) rpats)))
- where
- pp_rpat (v, p) = hsep [ppr v, char '=', ppr p]
+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
+pprPat (DictPat ds ms) = parens (sep [ptext SLIT("{-dict-}"),
+ brackets (interpp'SP ds),
+ brackets (interpp'SP ms)])
+
+pprUserCon c (InfixCon p1 p2) = ppr p1 <+> ppr c <+> ppr p2
+pprUserCon c details = ppr c <+> pprConArgs details
+
+pprConArgs (PrefixCon pats) = interppSP pats
+pprConArgs (InfixCon p1 p2) = interppSP [p1,p2]
+pprConArgs (RecCon rpats) = braces (hsep (punctuate comma (map (pp_rpat) rpats)))
+ where
+ pp_rpat (v, p) = hsep [ppr v, char '=', ppr p]
-- add parallel array brackets around a document
\begin{code}
mkPrefixConPat :: DataCon -> [OutPat id] -> Type -> OutPat id
-- Make a vanilla Prefix constructor pattern
-mkPrefixConPat dc pats ty = ConPatOut dc (PrefixCon pats) ty [] []
+mkPrefixConPat dc pats ty = noLoc $ ConPatOut (noLoc dc) [] [] emptyLHsBinds (PrefixCon pats) ty
mkNilPat :: Type -> OutPat id
mkNilPat ty = mkPrefixConPat nilDataCon [] ty
-mkCharLitPat :: Int -> OutPat id
-mkCharLitPat c = mkPrefixConPat charDataCon [LitPat (HsCharPrim c)] charTy
+mkCharLitPat :: Char -> OutPat id
+mkCharLitPat c = mkPrefixConPat charDataCon [noLoc $ LitPat (HsCharPrim c)] charTy
\end{code}
The 1.3 report defines what ``irrefutable'' and ``failure-free'' patterns are.
\begin{code}
-failureFreePat :: OutPat id -> Bool
-
-failureFreePat (WildPat _) = True
-failureFreePat (VarPat _) = True
-failureFreePat (LazyPat _) = True
-failureFreePat (ParPat _) = True
-failureFreePat (AsPat _ pat) = failureFreePat pat
-
-failureFreePat (ListPat _ _) = False
-failureFreePat (PArrPat _ _) = False
-failureFreePat (TuplePat pats _) = all failureFreePat pats
-
-failureFreePat (ConPatOut con ps _ _ _) = only_con con && failure_free_con ps
-
-failureFreePat (SigPatOut p _ _) = failureFreePat p
-
-failureFreePat (DictPat _ _) = True
-
-failureFreePat other_pat = False -- Literals, NPat
-
-failure_free_con (PrefixCon pats) = all failureFreePat pats
-failure_free_con (InfixCon p1 p2) = failureFreePat p1 && failureFreePat p2
-failure_free_con (RecCon fs) = all (failureFreePat . snd) fs
-
-only_con con = maybeToBool (maybeTyConSingleCon (dataConTyCon con))
-\end{code}
-
-\begin{code}
isWildPat (WildPat _) = True
isWildPat other = False
patsAreAllCons :: [Pat id] -> Bool
patsAreAllCons pat_list = all isConPat pat_list
-isConPat (AsPat _ pat) = isConPat pat
-isConPat (ConPatIn _ _) = True
-isConPat (ConPatOut _ _ _ _ _) = True
-isConPat (ListPat _ _) = True
-isConPat (PArrPat _ _) = True
-isConPat (TuplePat _ _) = True
-isConPat (DictPat ds ms) = (length ds + length ms) > 1
-isConPat other = False
+isConPat (AsPat _ pat) = isConPat (unLoc pat)
+isConPat (ConPatIn _ _) = True
+isConPat (ConPatOut _ _ _ _ _ _) = True
+isConPat (ListPat _ _) = True
+isConPat (PArrPat _ _) = True
+isConPat (TuplePat _ _ _) = True
+isConPat (DictPat ds ms) = (length ds + length ms) > 1
+isConPat other = False
-isSigPat (SigPatIn _ _) = True
-isSigPat (SigPatOut _ _ _) = True
-isSigPat other = False
+isSigPat (SigPatIn _ _) = True
+isSigPat (SigPatOut _ _) = True
+isSigPat other = False
patsAreAllLits :: [Pat id] -> Bool
patsAreAllLits pat_list = all isLitPat pat_list
-isLitPat (AsPat _ pat) = isLitPat pat
+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
-\end{code}
-
-%************************************************************************
-%* *
-%* Gathering stuff out of patterns
-%* *
-%************************************************************************
-
-This function @collectPatBinders@ works with the ``collectBinders''
-functions for @HsBinds@, etc. The order in which the binders are
-collected is important; see @HsBinds.lhs@.
-
-It collects the bounds *value* variables in renamed patterns; type variables
-are *not* collected.
-\begin{code}
-collectPatBinders :: Pat a -> [a]
-collectPatBinders pat = collect pat []
-
-collectPatsBinders :: [Pat a] -> [a]
-collectPatsBinders pats = foldr collect [] pats
-
-collect (WildPat _) bndrs = bndrs
-collect (VarPat var) bndrs = var : bndrs
-collect (LazyPat pat) bndrs = collect pat bndrs
-collect (AsPat a pat) bndrs = a : collect pat bndrs
-collect (ParPat pat) bndrs = collect pat bndrs
-
-collect (ListPat pats _) bndrs = foldr collect bndrs pats
-collect (PArrPat pats _) bndrs = foldr collect bndrs pats
-collect (TuplePat pats _) bndrs = foldr collect bndrs pats
-
-collect (ConPatIn c ps) bndrs = foldr collect bndrs (hsConArgs ps)
-collect (ConPatOut c ps _ _ ds) bndrs = ds ++ foldr collect bndrs (hsConArgs ps)
-
-collect (LitPat _) bndrs = bndrs
-collect (NPatIn _ _) bndrs = bndrs
-collect (NPatOut _ _ _) bndrs = bndrs
-
-collect (NPlusKPatIn n _ _) bndrs = n : bndrs
-collect (NPlusKPatOut n _ _ _) bndrs = n : bndrs
-
-collect (SigPatIn pat _) bndrs = collect pat bndrs
-collect (SigPatOut pat _ _) bndrs = collect pat bndrs
-collect (TypePat ty) bndrs = bndrs
-collect (DictPat ids1 ids2) bndrs = ids1 ++ ids2 ++ bndrs
-\end{code}
-
-\begin{code}
-collectSigTysFromPats :: [InPat name] -> [HsType name]
-collectSigTysFromPats pats = foldr collect_pat [] pats
-
-collectSigTysFromPat :: InPat name -> [HsType name]
-collectSigTysFromPat pat = collect_pat pat []
-
-collect_pat (SigPatIn pat ty) acc = collect_pat pat (ty:acc)
-collect_pat (TypePat ty) acc = ty:acc
-
-collect_pat (LazyPat pat) acc = collect_pat pat acc
-collect_pat (AsPat a pat) acc = collect_pat pat acc
-collect_pat (ParPat pat) acc = collect_pat pat acc
-collect_pat (ListPat pats _) acc = foldr collect_pat acc pats
-collect_pat (PArrPat pats _) acc = foldr collect_pat acc pats
-collect_pat (TuplePat pats _) acc = foldr collect_pat acc pats
-collect_pat (ConPatIn c ps) acc = foldr collect_pat acc (hsConArgs ps)
-collect_pat other acc = acc -- Literals, vars, wildcard
+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