InPat(..),
OutPat(..),
- unfailablePats, unfailablePat,
+ irrefutablePat, irrefutablePats,
+ failureFreePat,
patsAreAllCons, isConPat,
patsAreAllLits, isLitPat,
- irrefutablePat,
collectPatBinders
) where
-import Ubiq
+IMP_Ubiq()
-- friends:
import HsLit ( HsLit )
-import HsLoop ( HsExpr )
+IMPORT_DELOOPER(HsLoop) ( HsExpr )
-- others:
-import Id ( GenId, dataConSig )
+import Id ( dataConTyCon, GenId )
import Maybes ( maybeToBool )
import Name ( pprSym, pprNonSym )
import Outputable ( interppSP, interpp'SP, ifPprShowAll )
[(name, InPat name, Bool)] -- True <=> source used punning
data OutPat tyvar uvar id
- = WildPat (GenType tyvar uvar) -- wild card
+ = WildPat (GenType tyvar uvar) -- wild card
| VarPat id -- variable (type is in the Id)
| ConPat Id -- Constructor is always an Id
(GenType tyvar uvar) -- the type of the pattern
- [(OutPat tyvar uvar id)]
+ [OutPat tyvar uvar id]
| ConOpPat (OutPat tyvar uvar id) -- just a special case...
Id
(GenType tyvar uvar)
| ListPat -- syntactic list
(GenType tyvar uvar) -- the type of the elements
- [(OutPat tyvar uvar id)]
+ [OutPat tyvar uvar id]
- | TuplePat [(OutPat tyvar uvar id)] -- tuple
+ | 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
+ [(Id, OutPat tyvar uvar id, Bool)] -- True <=> source used punning
| LitPat -- Used for *non-overloaded* literal patterns:
-- Int#, Char#, Int, Char, String, etc.
(HsExpr tyvar uvar id (OutPat tyvar uvar id))
-- of type t -> Bool; detects match
- | DictPat -- Used when destructing Dictionaries with an explicit case
+ | DictPat -- Used when destructing Dictionaries with an explicit case
[id] -- superclass dicts
[id] -- methods
\end{code}
= if null pats then
ppr sty c
else
- ppBesides [ppLparen, ppr sty c, ppSP, interppSP sty pats, ppRparen]
-
+ ppCat [ppr sty c, interppSP sty pats] -- ParPats put in the parens
pprInPat sty (ConOpPatIn pat1 op pat2)
- = ppBesides [ppLparen, ppr sty pat1, ppSP, ppr sty op, ppSP, ppr sty pat2, ppRparen]
+ = ppCat [ppr sty pat1, ppr sty op, ppr sty 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 (ListPatIn pats)
= ppBesides [ppLbrack, interpp'SP sty pats, ppRbrack]
pprInPat sty (TuplePatIn pats)
- = ppBesides [ppLparen, interpp'SP sty pats, ppRparen]
+ = ppParens (interpp'SP sty pats)
pprInPat sty (RecPatIn con rpats)
- = ppBesides [ppr sty con, ppSP, ppChar '{', ppInterleave ppComma (map pp_rpat rpats), ppChar '}']
+ = ppBesides [ppr sty con, ppSP, ppChar '{', ppInterleave ppComma (map (pp_rpat sty) rpats), ppChar '}']
where
- pp_rpat (v, _, True{-pun-}) = ppr sty v
- pp_rpat (v, p, _) = ppCat [ppr sty v, ppStr "<-", ppr sty p]
+ pp_rpat PprForUser (v, _, True) = ppr PprForUser v
+ pp_rpat sty (v, p, _) = ppCat [ppr sty v, ppStr "=", ppr sty p]
\end{code}
\begin{code}
pprOutPat sty (ListPat ty pats)
= ppBesides [ppLbrack, interpp'SP sty pats, ppRbrack]
pprOutPat sty (TuplePat pats)
- = ppBesides [ppLparen, interpp'SP sty pats, ppRparen]
+ = ppParens (interpp'SP sty pats)
pprOutPat sty (RecPat con ty rpats)
- = ppBesides [ppr sty con, ppChar '{', ppInterleave ppComma (map pp_rpat rpats), ppChar '}']
+ = ppBesides [ppr sty con, ppChar '{', ppInterleave ppComma (map (pp_rpat sty) rpats), ppChar '}']
where
--- pp_rpat (v, _, True{-pun-}) = ppr sty v
- pp_rpat (v, p, _) = ppBesides [ppr sty v, ppStr "<-", ppr sty p]
+ pp_rpat PprForUser (v, _, True) = ppr PprForUser v
+ pp_rpat sty (v, p, _) = ppCat [ppr sty v, ppStr "=", ppr sty p]
pprOutPat sty (LitPat l ty) = ppr sty l -- ToDo: print more
pprOutPat sty (NPat l ty e) = ppr sty l -- ToDo: print more
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
-
-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
+irrefutablePats :: [OutPat a b c] -> 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 a b c -> 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 (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}
+\begin{code}
patsAreAllCons :: [OutPat a b c] -> Bool
patsAreAllCons pat_list = all isConPat pat_list
isConPat (ConOpPat _ _ _ _) = True
isConPat (ListPat _ _) = True
isConPat (TuplePat _) = True
+isConPat (RecPat _ _ _) = True
isConPat (DictPat ds ms) = (length ds + length ms) > 1
isConPat other = False
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
-\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 (VarPatIn var) = [var]
-collectPatBinders (LazyPatIn pat) = collectPatBinders pat
-collectPatBinders (AsPatIn a pat) = a : collectPatBinders pat
-collectPatBinders (ConPatIn c pats) = concat (map collectPatBinders pats)
+collectPatBinders WildPatIn = []
+collectPatBinders (VarPatIn var) = [var]
+collectPatBinders (LitPatIn _) = []
+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-} ]
+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)
\end{code}
projects / ghc-hetmet.git / blobdiff