%
-% (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(..),
irrefutablePat, irrefutablePats,
- failureFreePat,
- patsAreAllCons, isConPat,
+ failureFreePat, isWildPat,
+ patsAreAllCons, isConPat,
patsAreAllLits, isLitPat,
- collectPatBinders
+ collectPatBinders, collectOutPatBinders, collectPatsBinders,
+ collectSigTysFromPat, collectSigTysFromPats
) where
-IMP_Ubiq()
+#include "HsVersions.h"
+
-- friends:
--- IMPORT_DELOOPER(IdLoop)
-import HsBasic ( HsLit )
+import HsLit ( HsLit, HsOverLit )
import HsExpr ( HsExpr )
-import BasicTypes ( Fixity )
+import HsTypes ( HsType )
+import BasicTypes ( Fixity, Boxity, tupleParens )
-- others:
-import Id ( SYN_IE(Id), dataConTyCon, GenId )
+import Name ( Name )
+import Var ( Id, TyVar )
+import DataCon ( DataCon, dataConTyCon )
+import Name ( isDataSymOcc, getOccName, NamedThing )
import Maybes ( maybeToBool )
-import Outputable ( PprStyle(..), userStyle, interppSP,
- interpp'SP, ifPprShowAll, Outputable(..)
- )
-import Pretty
+import Outputable
import TyCon ( maybeTyConSingleCon )
-import PprType ( GenType )
-import CmdLineOpts ( opt_PprUserLength )
-#if __GLASGOW_HASKELL__ >= 202
-import Name
-#endif
+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)
Fixity -- c.f. OpApp in HsExpr
(InPat name)
- | NPlusKPatIn name -- n+k pattern
- HsLit
+ | NPatIn HsOverLit -- Always positive
+ (Maybe Name) -- Just (Name of 'negate') for negative
+ -- patterns, Nothing otherwise
+ -- (see RnEnv.lookupSyntaxName)
+
+ | NPlusKPatIn name -- n+k pattern
+ HsOverLit -- It'll always be an HsIntegral
+ Name -- Name of '-' (see RnEnv.lookupSyntaxName)
-- We preserve prefix negation and parenthesis for the precedence parser.
- | NegPatIn (InPat name) -- negated pattern
| ParPatIn (InPat name) -- parenthesised pattern
| ListPatIn [InPat name] -- syntactic list
-- must have >= 1 elements
- | TuplePatIn [InPat name] -- tuple
+ | PArrPatIn [InPat name] -- syntactic parallel array
+ -- must have >= 1 elements
+ | 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)
-
- | LazyPat (OutPat tyvar uvar id) -- lazy pattern
-
- | 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]
-
- | 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]
-
- | TuplePat [OutPat tyvar uvar id] -- tuple
- -- UnitPat is TuplePat []
-
- | RecPat Id -- record constructor
- (GenType tyvar uvar) -- the type of the pattern
- [(Id, OutPat tyvar uvar id, Bool)] -- True <=> source used punning
+-- Generics
+ | TypePatIn (HsType name) -- Type pattern for generic definitions
+ -- e.g f{| a+b |} = ...
+ -- These show up only in class
+ -- declarations,
+ -- and should be a top-level pattern
+
+-- /Generics
+
+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)
+
+ | SigPat (OutPat id) -- Pattern p
+ Type -- Type, t, of the whole pattern
+ (HsExpr id (OutPat id))
+ -- Coercion function,
+ -- of type t -> typeof(p)
+
+ | ListPat -- Syntactic list
+ Type -- The type of the elements
+ [OutPat id]
+ | PArrPat -- Syntactic parallel array
+ Type -- The type of the elements
+ [OutPat id]
+
+ | TuplePat [OutPat id] -- Tuple
+ Boxity
+ -- UnitPat is TuplePat []
+
+ | ConPat DataCon
+ Type -- the type of the pattern
+ [TyVar] -- Existentially bound type variables
+ [id] -- Ditto dictionaries
+ [OutPat id]
+
+ -- ConOpPats are only used on the input side
+
+ | 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
+ | NPat -- Used for literal patterns where there's an equality function to call
+ 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))
- -- of type t -> Bool; detects match
+ -- Always HsInteger, HsRat or HsString.
+ -- *Unlike* NPatIn, for negative literals, the
+ -- literal is acutally negative!
+ Type -- Type of pattern, t
+ (HsExpr id (OutPat id)) -- Of type t -> Bool; detects match
| NPlusKPat id
- HsLit -- Same reason as for LitPat
- -- (This could be an Integer, but then
- -- it's harder to partitionEqnsByLit
- -- in the desugarer.)
- (GenType tyvar uvar) -- Type of pattern, t
- (HsExpr tyvar uvar id (OutPat tyvar uvar id)) -- Of type t -> Bool; detects match
- (HsExpr tyvar uvar id (OutPat tyvar uvar id)) -- Of type t -> t; subtracts k
+ Integer
+ 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
instance (Outputable name) => Outputable (InPat name) where
ppr = pprInPat
-pprInPat :: (Outputable name) => PprStyle -> InPat name -> Doc
+pprInPat :: (Outputable name) => InPat name -> SDoc
-pprInPat sty (WildPatIn) = char '_'
-pprInPat sty (VarPatIn var) = ppr sty var
-pprInPat sty (LitPatIn s) = ppr sty s
-pprInPat sty (LazyPatIn pat) = (<>) (char '~') (ppr sty pat)
-pprInPat sty (AsPatIn name pat)
- = parens (hcat [ppr sty name, char '@', ppr sty pat])
+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 (ParPatIn pat) = parens (pprInPat pat)
+pprInPat (ListPatIn pats) = brackets (interpp'SP pats)
+pprInPat (PArrPatIn pats) = pabrackets (interpp'SP pats)
+pprInPat (TuplePatIn pats bx) = tupleParens bx (interpp'SP pats)
+pprInPat (NPlusKPatIn n k _) = parens (hcat [ppr n, char '+', ppr k])
+pprInPat (NPatIn l _) = ppr l
-pprInPat sty (ConPatIn c pats)
- = if null pats then
- ppr sty c
- else
- hsep [ppr sty c, interppSP sty pats] -- ParPats put in the parens
+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 fixity pat2)
- = hsep [ppr sty pat1, ppr sty op, ppr sty pat2] -- ParPats put in parens
+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)
- = let
- pp_pat = pprInPat sty pat
- in
- (<>) (char '-') (
- case pat of
- LitPatIn _ -> pp_pat
- _ -> parens pp_pat
- )
-
-pprInPat sty (ParPatIn pat)
- = parens (pprInPat sty pat)
-
-pprInPat sty (ListPatIn pats)
- = brackets (interpp'SP sty pats)
-pprInPat sty (TuplePatIn pats)
- = parens (interpp'SP sty pats)
-pprInPat sty (NPlusKPatIn n k)
- = parens (hcat [ppr sty n, char '+', ppr sty k])
-
-pprInPat sty (RecPatIn con rpats)
- = hsep [ppr sty con, braces (hsep (punctuate comma (map (pp_rpat sty) rpats)))]
+pprInPat (RecPatIn con rpats)
+ = hsep [ppr con, braces (hsep (punctuate comma (map (pp_rpat) rpats)))]
where
- pp_rpat sty (v, _, True) | userStyle sty = ppr (PprForUser opt_PprUserLength) v
- pp_rpat sty (v, p, _) = hsep [ppr sty v, char '=', ppr sty p]
+ pp_rpat (v, _, True) = ppr v
+ pp_rpat (v, p, _) = hsep [ppr v, char '=', ppr p]
+
+pprInPat (TypePatIn ty) = ptext SLIT("{|") <> ppr ty <> ptext SLIT("|}")
+
+-- add parallel array brackets around a document
+--
+pabrackets :: SDoc -> SDoc
+pabrackets p = ptext SLIT("[:") <> p <> ptext SLIT(":]")
\end{code}
\begin{code}
-instance (Eq tyvar, Outputable tyvar, Eq uvar, Outputable uvar, 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) = char '_'
-pprOutPat sty (VarPat var) = ppr sty var
-pprOutPat sty (LazyPat pat) = hcat [char '~', ppr sty pat]
-pprOutPat sty (AsPat name pat)
- = parens (hcat [ppr sty name, char '@', ppr sty pat])
-
-pprOutPat sty (ConPat name ty [])
- = (<>) (ppr sty name)
- (ifPprShowAll sty (pprConPatTy sty ty))
-
-pprOutPat sty (ConPat name ty pats)
- = hcat [parens (hcat [ppr sty name, space, interppSP sty pats]),
- ifPprShowAll sty (pprConPatTy sty ty) ]
-
-pprOutPat sty (ConOpPat pat1 op pat2 ty)
- = parens (hcat [ppr sty pat1, space, ppr sty op, space, ppr sty pat2])
-
-pprOutPat sty (ListPat ty pats)
- = brackets (interpp'SP sty pats)
-pprOutPat sty (TuplePat pats)
- = parens (interpp'SP sty pats)
-
-pprOutPat sty (RecPat con ty rpats)
- = hcat [ppr sty con, braces (hsep (punctuate comma (map (pp_rpat sty) rpats)))]
+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 (SigPat pat ty _) = ppr pat <+> dcolon <+> ppr ty
+
+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 (PArrPat ty pats) = pabrackets (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 sty (v, _, True) | userStyle sty = ppr (PprForUser opt_PprUserLength) v
- pp_rpat sty (v, p, _) = hsep [ppr sty v, char '=', 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 sty (NPlusKPat n k ty e1 e2) -- ToDo: print more
- = parens (hcat [ppr sty n, char '+', ppr sty k])
+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 '+', integer k])
-pprOutPat sty (DictPat dicts methods)
+pprOutPat (DictPat dicts methods)
= parens (sep [ptext SLIT("{-dict-}"),
- brackets (interpp'SP sty dicts),
- brackets (interpp'SP sty methods)])
+ brackets (interpp'SP dicts),
+ brackets (interpp'SP methods)])
-pprConPatTy sty ty
- = parens (ppr sty ty)
\end{code}
%************************************************************************
The 1.3 report defines what ``irrefutable'' and ``failure-free'' patterns are.
\begin{code}
-irrefutablePats :: [OutPat a b c] -> Bool
+irrefutablePats :: [OutPat id] -> Bool
irrefutablePats pat_list = all irrefutablePat pat_list
irrefutablePat (AsPat _ pat) = irrefutablePat pat
irrefutablePat (DictPat ds ms) = (length ds + length ms) <= 1
irrefutablePat other = False
-failureFreePat :: OutPat a b c -> Bool
+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 (ConOpPat pat1 con pat2 _) = only_con con && failureFreePat pat1 && failureFreePat pat1
-failureFreePat (RecPat con _ fields) = only_con con && and [ failureFreePat pat | (_,pat,_) <- fields ]
+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 (PArrPat _ _) = False
+failureFreePat (TuplePat pats _) = all failureFreePat pats
failureFreePat (DictPat _ _) = True
failureFreePat other_pat = False -- Literals, NPat
\end{code}
\begin{code}
-patsAreAllCons :: [OutPat a b c] -> Bool
+isWildPat (WildPat _) = True
+isWildPat other = False
+
+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 (RecPat _ _ _) = True
+isConPat (PArrPat _ _) = 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
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 []
+
+collectOutPatBinders :: OutPat a -> [a]
+collectOutPatBinders pat = collectOut 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 (NPatIn _ _) bndrs = bndrs
+collect (ConPatIn c pats) bndrs = foldr collect bndrs pats
+collect (ConOpPatIn p1 c f p2) bndrs = collect p1 (collect p2 bndrs)
+collect (ParPatIn pat) bndrs = collect pat bndrs
+collect (ListPatIn pats) bndrs = foldr collect bndrs pats
+collect (PArrPatIn 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
+-- Generics
+collect (TypePatIn ty) bndrs = bndrs
+-- assume the type variables do not need to be bound
+
+-- collect the bounds *value* variables in renamed patterns; type variables
+-- are *not* collected
+--
+collectOut (WildPat _) bndrs = bndrs
+collectOut (VarPat var) bndrs = var : bndrs
+collectOut (LazyPat pat) bndrs = collectOut pat bndrs
+collectOut (AsPat a pat) bndrs = a : collectOut pat bndrs
+collectOut (ListPat _ pats) bndrs = foldr collectOut bndrs pats
+collectOut (PArrPat _ pats) bndrs = foldr collectOut bndrs pats
+collectOut (TuplePat pats _) bndrs = foldr collectOut bndrs pats
+collectOut (ConPat _ _ _ ds pats) bndrs = ds ++ foldr collectOut bndrs pats
+collectOut (RecPat _ _ _ ds fields) bndrs = ds ++ foldr comb bndrs fields
+ where
+ comb (_, pat, _) bndrs = collectOut pat bndrs
+collectOut (LitPat _ _) bndrs = bndrs
+collectOut (NPat _ _ _) bndrs = bndrs
+collectOut (NPlusKPat n _ _ _ _) bndrs = n : bndrs
+collectOut (DictPat ids1 ids2) bndrs = ids1 ++ ids2 ++ bndrs
+\end{code}
-collectPatBinders WildPatIn = []
-collectPatBinders (VarPatIn var) = [var]
-collectPatBinders (LitPatIn _) = []
-collectPatBinders (LazyPatIn pat) = collectPatBinders pat
-collectPatBinders (AsPatIn a pat) = a : collectPatBinders pat
-collectPatBinders (NPlusKPatIn n _) = [n]
-collectPatBinders (ConPatIn c pats) = concat (map collectPatBinders pats)
-collectPatBinders (ConOpPatIn p1 c f 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 (RecPatIn c fields) = concat (map (\ (f,pat,_) -> collectPatBinders pat) fields)
+\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 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 (NPatIn _ _) acc = 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 (ParPatIn pat) acc = collect_pat pat acc
+collect_pat (ListPatIn pats) acc = foldr collect_pat acc pats
+collect_pat (PArrPatIn 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
+-- Generics
+collect_pat (TypePatIn ty) acc = ty:acc
\end{code}
+
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