%
-% (c) The GRASP/AQUA Project, Glasgow University, 1992-1996
+% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
%
\section[PatSyntax]{Abstract Haskell syntax---patterns}
\begin{code}
-#include "HsVersions.h"
-
module HsPat (
InPat(..),
OutPat(..),
- unfailablePats, unfailablePat,
+ irrefutablePat, irrefutablePats,
+ failureFreePat, isWildPat,
patsAreAllCons, isConPat,
patsAreAllLits, isLitPat,
- irrefutablePat,
- collectPatBinders
+ collectPatBinders, collectPatsBinders,
+ collectSigTysFromPats
) where
-import Ubiq
+#include "HsVersions.h"
-- friends:
-import HsLit ( HsLit )
-import HsLoop ( HsExpr )
+import HsBasic ( HsLit )
+import HsExpr ( HsExpr )
+import HsTypes ( HsType )
+import BasicTypes ( Fixity, Boxity, tupleParens )
-- others:
-import Id ( GenId, dataConSig )
+import Var ( Id, TyVar )
+import DataCon ( DataCon, dataConTyCon )
+import Name ( isDataSymOcc, getOccName, NamedThing )
import Maybes ( maybeToBool )
-import Name ( pprSym, pprNonSym )
-import Outputable ( interppSP, interpp'SP, ifPprShowAll )
-import PprStyle ( PprStyle(..) )
-import Pretty
+import Outputable
import TyCon ( maybeTyConSingleCon )
-import PprType ( GenType )
+import Type ( Type )
\end{code}
Patterns come in distinct before- and after-typechecking flavo(u)rs.
| LazyPatIn (InPat name) -- lazy pattern
| AsPatIn name -- as pattern
(InPat name)
+ | SigPatIn (InPat name)
+ (HsType name)
| ConPatIn name -- constructed type
[InPat name]
| ConOpPatIn (InPat name)
name
+ Fixity -- c.f. OpApp in HsExpr
(InPat name)
+ | NPlusKPatIn name -- n+k pattern
+ HsLit
+
-- We preserve prefix negation and parenthesis for the precedence parser.
| NegPatIn (InPat name) -- negated pattern
| ListPatIn [InPat name] -- syntactic list
-- must have >= 1 elements
- | TuplePatIn [InPat name] -- tuple
+ | TuplePatIn [InPat name] Boxity -- tuple (boxed?)
| RecPatIn name -- record
[(name, InPat name, Bool)] -- True <=> source used punning
-data OutPat tyvar uvar id
- = WildPat (GenType tyvar uvar) -- wild card
-
- | VarPat id -- variable (type is in the Id)
+data OutPat id
+ = WildPat Type -- wild card
+ | VarPat id -- variable (type is in the Id)
+ | LazyPat (OutPat id) -- lazy pattern
+ | AsPat id -- as pattern
+ (OutPat id)
- | LazyPat (OutPat tyvar uvar id) -- lazy pattern
+ | ListPat -- syntactic list
+ Type -- the type of the elements
+ [OutPat id]
- | AsPat id -- as pattern
- (OutPat tyvar uvar id)
-
- | ConPat Id -- Constructor is always an Id
- (GenType tyvar uvar) -- the type of the pattern
- [(OutPat tyvar uvar id)]
+ | TuplePat [OutPat id] -- tuple
+ Boxity
+ -- UnitPat is TuplePat []
- | ConOpPat (OutPat tyvar uvar id) -- just a special case...
- Id
- (OutPat tyvar uvar id)
- (GenType tyvar uvar)
- | ListPat -- syntactic list
- (GenType tyvar uvar) -- the type of the elements
- [(OutPat tyvar uvar id)]
+ | ConPat DataCon
+ Type -- the type of the pattern
+ [TyVar] -- Existentially bound type variables
+ [id] -- Ditto dictionaries
+ [OutPat id]
- | TuplePat [(OutPat tyvar uvar id)] -- tuple
- -- UnitPat is TuplePat []
+ -- ConOpPats are only used on the input side
- | RecPat Id -- record constructor
- (GenType tyvar uvar) -- the type of the pattern
- [(id, OutPat tyvar uvar id, Bool)] -- True <=> source used punning
+ | RecPat DataCon -- record constructor
+ Type -- the type of the pattern
+ [TyVar] -- Existentially bound type variables
+ [id] -- Ditto dictionaries
+ [(Id, OutPat id, Bool)] -- True <=> source used punning
| LitPat -- Used for *non-overloaded* literal patterns:
-- Int#, Char#, Int, Char, String, etc.
HsLit
- (GenType tyvar uvar) -- type of pattern
+ Type -- type of pattern
| NPat -- Used for *overloaded* literal patterns
HsLit -- the literal is retained so that
-- the desugarer can readily identify
-- equations with identical literal-patterns
- (GenType tyvar uvar) -- type of pattern, t
- (HsExpr tyvar uvar id (OutPat tyvar uvar id))
+ Type -- type of pattern, t
+ (HsExpr id (OutPat id))
-- of type t -> Bool; detects match
- | DictPat -- Used when destructing Dictionaries with an explicit case
+ | NPlusKPat id
+ HsLit -- Same reason as for LitPat
+ -- (This could be an Integer, but then
+ -- it's harder to partitionEqnsByLit
+ -- in the desugarer.)
+ Type -- Type of pattern, t
+ (HsExpr id (OutPat id)) -- Of type t -> Bool; detects match
+ (HsExpr id (OutPat id)) -- Of type t -> t; subtracts k
+
+ | DictPat -- Used when destructing Dictionaries with an explicit case
[id] -- superclass dicts
[id] -- methods
\end{code}
+Now name in Inpat is not need to be in NAmedThing to be Outputable.
+Needed by ../deSugar/Check.lhs
+
+JJQC-2-12-97
+
\begin{code}
-instance (Outputable name, NamedThing name) => Outputable (InPat name) where
+instance (Outputable name) => Outputable (InPat name) where
ppr = pprInPat
-pprInPat :: (Outputable name, NamedThing name) => PprStyle -> InPat name -> Pretty
-
-pprInPat sty (WildPatIn) = ppStr "_"
-pprInPat sty (VarPatIn var) = pprNonSym sty var
-pprInPat sty (LitPatIn s) = ppr sty s
-pprInPat sty (LazyPatIn pat) = ppBeside (ppChar '~') (ppr sty pat)
-pprInPat sty (AsPatIn name pat)
- = ppBesides [ppLparen, ppr sty name, ppChar '@', ppr sty pat, ppRparen]
+pprInPat :: (Outputable name) => InPat name -> SDoc
-pprInPat sty (ConPatIn c pats)
- = if null pats then
- ppr sty c
- else
- ppBesides [ppLparen, ppr sty c, ppSP, interppSP sty pats, ppRparen]
+pprInPat (WildPatIn) = char '_'
+pprInPat (VarPatIn var) = ppr var
+pprInPat (LitPatIn s) = ppr s
+pprInPat (SigPatIn pat ty) = ppr pat <+> dcolon <+> ppr ty
+pprInPat (LazyPatIn pat) = char '~' <> ppr pat
+pprInPat (AsPatIn name pat) = parens (hcat [ppr name, char '@', ppr pat])
+pprInPat (ConPatIn c pats)
+ | null pats = ppr c
+ | otherwise = hsep [ppr c, interppSP pats] -- inner ParPats supply the necessary parens.
-pprInPat sty (ConOpPatIn pat1 op pat2)
- = ppBesides [ppLparen, ppr sty pat1, ppSP, ppr sty op, ppSP, ppr sty pat2, ppRparen]
+pprInPat (ConOpPatIn pat1 op fixity pat2)
+ = hsep [ppr pat1, ppr op, 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)
-pprInPat sty (NegPatIn pat)
+pprInPat (NegPatIn pat)
= let
- pp_pat = pprInPat sty pat
+ pp_pat = pprInPat pat
in
- ppBeside (ppChar '-') (
+ char '-' <> (
case pat of
LitPatIn _ -> pp_pat
- _ -> ppParens pp_pat
+ _ -> parens pp_pat
)
-pprInPat sty (ParPatIn pat)
- = ppParens (pprInPat sty pat)
+pprInPat (ParPatIn pat)
+ = parens (pprInPat pat)
-pprInPat sty (ListPatIn pats)
- = ppBesides [ppLbrack, interpp'SP sty pats, ppRbrack]
-pprInPat sty (TuplePatIn pats)
- = ppBesides [ppLparen, interpp'SP sty pats, ppRparen]
+pprInPat (ListPatIn pats)
+ = brackets (interpp'SP pats)
+pprInPat (TuplePatIn pats boxity)
+ = tupleParens boxity (interpp'SP pats)
+pprInPat (NPlusKPatIn n k)
+ = parens (hcat [ppr n, char '+', ppr k])
-pprInPat sty (RecPatIn con rpats)
- = ppBesides [ppr sty con, ppSP, ppChar '{', ppInterleave ppComma (map pp_rpat rpats), ppChar '}']
+pprInPat (RecPatIn con rpats)
+ = hsep [ppr con, braces (hsep (punctuate comma (map (pp_rpat) rpats)))]
where
- pp_rpat (v, _, True{-pun-}) = ppr sty v
- pp_rpat (v, p, _) = ppCat [ppr sty v, ppStr "<-", ppr sty p]
+ pp_rpat (v, _, True) = ppr v
+ pp_rpat (v, p, _) = hsep [ppr v, char '=', ppr p]
\end{code}
\begin{code}
-instance (Eq tyvar, Outputable tyvar, Eq uvar, Outputable uvar,
- NamedThing id, Outputable id)
- => Outputable (OutPat tyvar uvar id) where
+instance (NamedThing id, Outputable id) => Outputable (OutPat id) where
ppr = pprOutPat
\end{code}
\begin{code}
-pprOutPat sty (WildPat ty) = ppChar '_'
-pprOutPat sty (VarPat var) = pprNonSym sty var
-pprOutPat sty (LazyPat pat) = ppBesides [ppChar '~', ppr sty pat]
-pprOutPat sty (AsPat name pat)
- = ppBesides [ppLparen, ppr sty name, ppChar '@', ppr sty pat, ppRparen]
-
-pprOutPat sty (ConPat name ty [])
- = ppBeside (ppr sty name)
- (ifPprShowAll sty (pprConPatTy sty ty))
-
-pprOutPat sty (ConPat name ty pats)
- = ppBesides [ppLparen, ppr sty name, ppSP,
- interppSP sty pats, ppRparen,
- ifPprShowAll sty (pprConPatTy sty ty) ]
-
-pprOutPat sty (ConOpPat pat1 op pat2 ty)
- = ppBesides [ppLparen, ppr sty pat1, ppSP, pprSym sty op, ppSP, ppr sty pat2, ppRparen]
-
-pprOutPat sty (ListPat ty pats)
- = ppBesides [ppLbrack, interpp'SP sty pats, ppRbrack]
-pprOutPat sty (TuplePat pats)
- = ppBesides [ppLparen, interpp'SP sty pats, ppRparen]
-
-pprOutPat sty (RecPat con ty rpats)
- = ppBesides [ppr sty con, ppChar '{', ppInterleave ppComma (map pp_rpat rpats), ppChar '}']
+pprOutPat (WildPat ty) = char '_'
+pprOutPat (VarPat var) = ppr var
+pprOutPat (LazyPat pat) = hcat [char '~', ppr pat]
+pprOutPat (AsPat name pat)
+ = parens (hcat [ppr name, char '@', ppr pat])
+
+pprOutPat (ConPat name ty [] [] [])
+ = ppr name
+
+-- Kludge to get infix constructors to come out right
+-- when ppr'ing desugar warnings.
+pprOutPat (ConPat name ty tyvars dicts pats)
+ = getPprStyle $ \ sty ->
+ parens $
+ case pats of
+ [p1,p2]
+ | userStyle sty && isDataSymOcc (getOccName name) ->
+ hsep [ppr p1, ppr name, ppr p2]
+ _ -> hsep [ppr name, interppSP tyvars, interppSP dicts, interppSP pats]
+
+pprOutPat (ListPat ty pats) = brackets (interpp'SP pats)
+pprOutPat (TuplePat pats boxity) = tupleParens boxity (interpp'SP pats)
+
+pprOutPat (RecPat con ty tvs dicts rpats)
+ = hsep [ppr con, interppSP tvs, interppSP dicts, braces (hsep (punctuate comma (map (pp_rpat) rpats)))]
where
--- pp_rpat (v, _, True{-pun-}) = ppr sty v
- pp_rpat (v, p, _) = ppBesides [ppr sty v, ppStr "<-", ppr sty p]
+ pp_rpat (v, _, True) = ppr v
+ pp_rpat (v, p, _) = hsep [ppr v, char '=', ppr p]
-pprOutPat sty (LitPat l ty) = ppr sty l -- ToDo: print more
-pprOutPat sty (NPat l ty e) = ppr sty l -- ToDo: print more
+pprOutPat (LitPat l ty) = ppr l -- ToDo: print more
+pprOutPat (NPat l ty e) = ppr l -- ToDo: print more
+pprOutPat (NPlusKPat n k ty e1 e2) -- ToDo: print more
+ = parens (hcat [ppr n, char '+', ppr k])
-pprOutPat sty (DictPat dicts methods)
- = ppSep [ppBesides [ppLparen, ppPStr SLIT("{-dict-}")],
- ppBracket (interpp'SP sty dicts),
- ppBesides [ppBracket (interpp'SP sty methods), ppRparen]]
+pprOutPat (DictPat dicts methods)
+ = parens (sep [ptext SLIT("{-dict-}"),
+ brackets (interpp'SP dicts),
+ brackets (interpp'SP methods)])
-pprConPatTy sty ty
- = ppParens (ppr sty ty)
\end{code}
%************************************************************************
A pattern is in {\em exactly one} of the above three categories; `as'
patterns are treated specially, of course.
+The 1.3 report defines what ``irrefutable'' and ``failure-free'' patterns are.
\begin{code}
-unfailablePats :: [OutPat a b c] -> Bool
-unfailablePats pat_list = all unfailablePat pat_list
+irrefutablePats :: [OutPat id] -> Bool
+irrefutablePats pat_list = all irrefutablePat pat_list
+
+irrefutablePat (AsPat _ pat) = irrefutablePat pat
+irrefutablePat (WildPat _) = True
+irrefutablePat (VarPat _) = True
+irrefutablePat (LazyPat _) = True
+irrefutablePat (DictPat ds ms) = (length ds + length ms) <= 1
+irrefutablePat other = False
+
+failureFreePat :: OutPat id -> Bool
+
+failureFreePat (WildPat _) = True
+failureFreePat (VarPat _) = True
+failureFreePat (LazyPat _) = True
+failureFreePat (AsPat _ pat) = failureFreePat pat
+failureFreePat (ConPat con tys _ _ pats) = only_con con && all failureFreePat pats
+failureFreePat (RecPat con _ _ _ fields) = only_con con && and [ failureFreePat pat | (_,pat,_) <- fields ]
+failureFreePat (ListPat _ _) = False
+failureFreePat (TuplePat pats _) = all failureFreePat pats
+failureFreePat (DictPat _ _) = True
+failureFreePat other_pat = False -- Literals, NPat
+
+only_con con = maybeToBool (maybeTyConSingleCon (dataConTyCon con))
+\end{code}
-unfailablePat (AsPat _ pat) = unfailablePat pat
-unfailablePat (WildPat _) = True
-unfailablePat (VarPat _) = True
-unfailablePat (LazyPat _) = True
-unfailablePat (DictPat ds ms) = (length ds + length ms) <= 1
-unfailablePat other = False
+\begin{code}
+isWildPat (WildPat _) = True
+isWildPat other = False
-patsAreAllCons :: [OutPat a b c] -> Bool
+patsAreAllCons :: [OutPat id] -> Bool
patsAreAllCons pat_list = all isConPat pat_list
isConPat (AsPat _ pat) = isConPat pat
-isConPat (ConPat _ _ _) = True
-isConPat (ConOpPat _ _ _ _) = True
+isConPat (ConPat _ _ _ _ _) = True
isConPat (ListPat _ _) = True
-isConPat (TuplePat _) = True
+isConPat (TuplePat _ _) = True
+isConPat (RecPat _ _ _ _ _) = True
isConPat (DictPat ds ms) = (length ds + length ms) > 1
isConPat other = False
-patsAreAllLits :: [OutPat a b c] -> Bool
+patsAreAllLits :: [OutPat id] -> Bool
patsAreAllLits pat_list = all isLitPat pat_list
-isLitPat (AsPat _ pat) = isLitPat pat
-isLitPat (LitPat _ _) = True
-isLitPat (NPat _ _ _) = True
-isLitPat other = False
-\end{code}
-
-A pattern is irrefutable if a match on it cannot fail
-(at any depth).
-\begin{code}
-irrefutablePat :: OutPat a b c -> Bool
-
-irrefutablePat (WildPat _) = True
-irrefutablePat (VarPat _) = True
-irrefutablePat (LazyPat _) = True
-irrefutablePat (AsPat _ pat) = irrefutablePat pat
-irrefutablePat (ConPat con tys pats) = all irrefutablePat pats && only_con con
-irrefutablePat (ConOpPat pat1 con pat2 _) = irrefutablePat pat1 && irrefutablePat pat1 && only_con con
-irrefutablePat (ListPat _ _) = False
-irrefutablePat (TuplePat pats) = all irrefutablePat pats
-irrefutablePat (DictPat _ _) = True
-irrefutablePat other_pat = False -- Literals, NPat
-
-only_con con = maybeToBool (maybeTyConSingleCon tycon)
- where
- (_,_,_,tycon) = dataConSig con
+isLitPat (AsPat _ pat) = isLitPat pat
+isLitPat (LitPat _ _) = True
+isLitPat (NPat _ _ _) = True
+isLitPat (NPlusKPat _ _ _ _ _) = True
+isLitPat other = False
\end{code}
This function @collectPatBinders@ works with the ``collectBinders''
functions for @HsBinds@, etc. The order in which the binders are
collected is important; see @HsBinds.lhs@.
+
\begin{code}
collectPatBinders :: InPat a -> [a]
+collectPatBinders pat = collect pat []
+
+collectPatsBinders :: [InPat a] -> [a]
+collectPatsBinders pats = foldr collect [] pats
+
+collect WildPatIn bndrs = bndrs
+collect (VarPatIn var) bndrs = var : bndrs
+collect (LitPatIn _) bndrs = bndrs
+collect (SigPatIn pat _) bndrs = collect pat bndrs
+collect (LazyPatIn pat) bndrs = collect pat bndrs
+collect (AsPatIn a pat) bndrs = a : collect pat bndrs
+collect (NPlusKPatIn n _) bndrs = n : bndrs
+collect (ConPatIn c pats) bndrs = foldr collect bndrs pats
+collect (ConOpPatIn p1 c f p2) bndrs = collect p1 (collect p2 bndrs)
+collect (NegPatIn pat) bndrs = collect pat bndrs
+collect (ParPatIn pat) bndrs = collect pat bndrs
+collect (ListPatIn pats) bndrs = foldr collect bndrs pats
+collect (TuplePatIn pats _) bndrs = foldr collect bndrs pats
+collect (RecPatIn c fields) bndrs = foldr (\ (f,pat,_) bndrs -> collect pat bndrs) bndrs fields
+\end{code}
-collectPatBinders (VarPatIn var) = [var]
-collectPatBinders (LazyPatIn pat) = collectPatBinders pat
-collectPatBinders (AsPatIn a pat) = a : collectPatBinders pat
-collectPatBinders (ConPatIn c pats) = concat (map collectPatBinders pats)
-collectPatBinders (ConOpPatIn p1 c p2)= collectPatBinders p1 ++ collectPatBinders p2
-collectPatBinders (NegPatIn pat) = collectPatBinders pat
-collectPatBinders (ParPatIn pat) = collectPatBinders pat
-collectPatBinders (ListPatIn pats) = concat (map collectPatBinders pats)
-collectPatBinders (TuplePatIn pats) = concat (map collectPatBinders pats)
-collectPatBinders any_other_pat = [ {-no binders-} ]
+
+\begin{code}
+collectSigTysFromPats :: [InPat name] -> [HsType name]
+collectSigTysFromPats pats = foldr collect_pat [] pats
+
+collect_pat (SigPatIn pat ty) acc = collect_pat pat (ty:acc)
+collect_pat WildPatIn acc = acc
+collect_pat (VarPatIn var) acc = acc
+collect_pat (LitPatIn _) acc = acc
+collect_pat (LazyPatIn pat) acc = collect_pat pat acc
+collect_pat (AsPatIn a pat) acc = collect_pat pat acc
+collect_pat (NPlusKPatIn n _) acc = acc
+collect_pat (ConPatIn c pats) acc = foldr collect_pat acc pats
+collect_pat (ConOpPatIn p1 c f p2) acc = collect_pat p1 (collect_pat p2 acc)
+collect_pat (NegPatIn pat) acc = collect_pat pat acc
+collect_pat (ParPatIn pat) acc = collect_pat pat acc
+collect_pat (ListPatIn pats) acc = foldr collect_pat acc pats
+collect_pat (TuplePatIn pats _) acc = foldr collect_pat acc pats
+collect_pat (RecPatIn c fields) acc = foldr (\ (f,pat,_) acc -> collect_pat pat acc) acc fields
\end{code}
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