OutPat(..),
irrefutablePat, irrefutablePats,
- failureFreePat,
+ failureFreePat, isWildPat,
patsAreAllCons, isConPat,
patsAreAllLits, isLitPat,
- collectPatBinders
+ collectPatBinders, collectPatsBinders,
+ collectSigTysFromPats
) where
#include "HsVersions.h"
+
-- friends:
-import HsBasic ( HsLit )
+import HsLit ( HsLit, HsOverLit )
import HsExpr ( HsExpr )
-import BasicTypes ( Fixity )
+import HsTypes ( HsType )
+import BasicTypes ( Fixity, Boxity, tupleParens )
-- others:
-import Var ( Id, GenTyVar )
+import Var ( Id, TyVar )
import DataCon ( DataCon, dataConTyCon )
+import Name ( isDataSymOcc, getOccName, NamedThing )
import Maybes ( maybeToBool )
import Outputable
import TyCon ( maybeTyConSingleCon )
-import Type ( 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)
Fixity -- c.f. OpApp in HsExpr
(InPat name)
- | NPlusKPatIn name -- n+k pattern
- HsLit
+ | NPatIn HsOverLit
+
+ | NPlusKPatIn name -- n+k pattern
+ HsOverLit -- It'll always be an HsIntegral
-- 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] Bool -- tuple (boxed?)
+ | TuplePatIn [InPat name] Boxity -- tuple (boxed?)
| RecPatIn name -- record
[(name, InPat name, Bool)] -- True <=> source used punning
-data OutPat flexi id
- = WildPat (GenType flexi) -- wild card
+-- 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
- | VarPat id -- variable (type is in the Id)
+-- /Generics
- | LazyPat (OutPat flexi id) -- lazy pattern
+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)
- | AsPat id -- as pattern
- (OutPat flexi id)
+ | ListPat -- Syntactic list
+ Type -- The type of the elements
+ [OutPat id]
- | ListPat -- syntactic list
- (GenType flexi) -- the type of the elements
- [OutPat flexi id]
-
- | TuplePat [OutPat flexi id] -- tuple
- Bool -- boxed?
- -- UnitPat is TuplePat []
+ | TuplePat [OutPat id] -- Tuple
+ Boxity
+ -- UnitPat is TuplePat []
| ConPat DataCon
- (GenType flexi) -- the type of the pattern
- [GenTyVar flexi] -- Existentially bound type variables
- [id] -- Ditto dictionaries
- [OutPat flexi id]
+ 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
- (GenType flexi) -- the type of the pattern
- [GenTyVar flexi] -- Existentially bound type variables
+ | RecPat DataCon -- Record constructor
+ Type -- The type of the pattern
+ [TyVar] -- Existentially bound type variables
[id] -- Ditto dictionaries
- [(Id, OutPat flexi id, Bool)] -- True <=> source used punning
+ [(Id, OutPat id, Bool)] -- True <=> source used punning
| LitPat -- Used for *non-overloaded* literal patterns:
-- Int#, Char#, Int, Char, String, etc.
HsLit
- (GenType flexi) -- type of pattern
+ Type -- Type of pattern
| NPat -- Used for *overloaded* literal patterns
- HsLit -- the literal is retained so that
+ HsLit -- The literal is retained so that
-- the desugarer can readily identify
-- equations with identical literal-patterns
- (GenType flexi) -- type of pattern, t
- (HsExpr flexi id (OutPat flexi id))
- -- of type t -> Bool; detects match
+ -- Always HsInt, HsRat or HsString.
+ 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 flexi) -- Type of pattern, t
- (HsExpr flexi id (OutPat flexi id)) -- Of type t -> Bool; detects match
- (HsExpr flexi id (OutPat flexi 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
pprInPat :: (Outputable name) => InPat name -> SDoc
-pprInPat (WildPatIn) = char '_'
-pprInPat (VarPatIn var) = ppr var
-pprInPat (LitPatIn s) = ppr s
-pprInPat (LazyPatIn pat) = char '~' <> ppr pat
-pprInPat (AsPatIn name pat) = parens (hcat [ppr name, char '@', ppr 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 (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 (ConPatIn c pats)
| null pats = ppr c
- | otherwise = hsep [ppr c, interppSP pats] -- ParPats put in the parens
+ | otherwise = hsep [ppr c, interppSP pats] -- inner ParPats supply the necessary 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 (NegPatIn pat)
- = let
- pp_pat = pprInPat pat
- in
- char '-' <> (
- case pat of
- LitPatIn _ -> pp_pat
- _ -> parens pp_pat
- )
-
-pprInPat (ParPatIn pat)
- = parens (pprInPat pat)
-
-pprInPat (ListPatIn pats)
- = brackets (interpp'SP pats)
-pprInPat (TuplePatIn pats False)
- = text "(#" <> (interpp'SP pats) <> text "#)"
-pprInPat (TuplePatIn pats True)
- = parens (interpp'SP pats)
-pprInPat (NPlusKPatIn n k)
- = parens (hcat [ppr n, char '+', ppr k])
-
pprInPat (RecPatIn con rpats)
= hsep [ppr con, braces (hsep (punctuate comma (map (pp_rpat) rpats)))]
where
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("|}")
\end{code}
\begin{code}
-instance (Outputable id) => Outputable (OutPat flexi id) where
+instance (NamedThing id, Outputable id) => Outputable (OutPat id) where
ppr = pprOutPat
\end{code}
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)
- = parens (hsep [ppr name, interppSP tyvars, interppSP dicts, interppSP 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 boxed@True)
- = parens (interpp'SP pats)
-pprOutPat (TuplePat pats unboxed@False)
- = text "(#" <> (interpp'SP pats) <> text "#)"
+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)))]
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])
+ = parens (hcat [ppr n, char '+', integer k])
pprOutPat (DictPat dicts methods)
= parens (sep [ptext SLIT("{-dict-}"),
The 1.3 report defines what ``irrefutable'' and ``failure-free'' patterns are.
\begin{code}
-irrefutablePats :: [OutPat a b] -> 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 -> Bool
+failureFreePat :: OutPat id -> Bool
failureFreePat (WildPat _) = True
failureFreePat (VarPat _) = True
\end{code}
\begin{code}
-patsAreAllCons :: [OutPat a b] -> Bool
+isWildPat (WildPat _) = True
+isWildPat other = False
+
+patsAreAllCons :: [OutPat id] -> Bool
patsAreAllCons pat_list = all isConPat pat_list
isConPat (AsPat _ pat) = isConPat pat
isConPat (DictPat ds ms) = (length ds + length ms) > 1
isConPat other = False
-patsAreAllLits :: [OutPat a b] -> 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 []
+
+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 (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
+\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
+
+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 (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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