mkPrefixConPat, mkCharLitPat, mkNilPat,
- isBangHsBind, isBangLPat, hsPatNeedsParens,
- isIrrefutableHsPat,
+ isBangHsBind, isLiftedPatBind,
+ isBangLPat, hsPatNeedsParens,
+ isIrrefutableHsPat,
pprParendLPat
) where
import FastString
-- libraries:
import Data.Data hiding (TyCon)
+import Data.Maybe
\end{code}
-- support hsPatType :: Pat Id -> Type
| VarPat id -- Variable
- | VarPatOut id TcEvBinds -- Used only for overloaded Ids; the
- -- bindings give its overloaded instances
- | LazyPat (LPat id) -- Lazy pattern
+ | LazyPat (LPat id) -- Lazy pattern
| AsPat (Located id) (LPat id) -- As pattern
| ParPat (LPat id) -- Parenthesised pattern
| BangPat (LPat id) -- Bang pattern
| LitPat HsLit -- Used for *non-overloaded* literal patterns:
-- Int#, Char#, Int, Char, String, etc.
- | NPat (HsOverLit id) -- ALWAYS positive
+ | NPat -- Used for all overloaded literals,
+ -- including overloaded strings with -XOverloadedStrings
+ (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
(SyntaxExpr id) -- (>=) function, of type t->t->Bool
(SyntaxExpr id) -- Name of '-' (see RnEnv.lookupSyntaxName)
- ------------ Generics ---------------
- | 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 (LPat id) -- Pattern with a type signature
(LHsType id)
pprPat :: (OutputableBndr name) => Pat name -> SDoc
pprPat (VarPat var) = pprPatBndr var
-pprPat (VarPatOut var bs) = pprPatBndr var <+> braces (ppr bs)
pprPat (WildPat _) = char '_'
pprPat (LazyPat pat) = char '~' <> pprParendLPat pat
pprPat (BangPat pat) = char '!' <> pprParendLPat pat
pprPat (NPat l (Just _) _) = char '-' <> ppr l
pprPat (NPlusKPat n k _ _) = hcat [ppr n, char '+', ppr k]
pprPat (QuasiQuotePat qq) = ppr qq
-pprPat (TypePat ty) = ptext (sLit "{|") <> ppr ty <> ptext (sLit "|}")
pprPat (CoPat co pat _) = pprHsWrapper (ppr pat) co
pprPat (SigPatIn pat ty) = ppr pat <+> dcolon <+> ppr ty
pprPat (SigPatOut pat ty) = ppr pat <+> dcolon <+> ppr ty
isBangLPat _ = False
isBangHsBind :: HsBind id -> Bool
--- In this module because HsPat is above HsBinds in the import graph
+-- A pattern binding with an outermost bang
+-- Defined in this module because HsPat is above HsBinds in the import graph
isBangHsBind (PatBind { pat_lhs = p }) = isBangLPat p
isBangHsBind _ = False
+isLiftedPatBind :: HsBind id -> Bool
+-- A pattern binding with a compound pattern, not just a variable
+-- (I# x) yes
+-- (# a, b #) no, even if a::Int#
+-- x no, even if x::Int#
+-- We want to warn about a missing bang-pattern on the yes's
+isLiftedPatBind (PatBind { pat_lhs = p }) = isLiftedLPat p
+isLiftedPatBind _ = False
+
+isLiftedLPat :: LPat id -> Bool
+isLiftedLPat (L _ (ParPat p)) = isLiftedLPat p
+isLiftedLPat (L _ (BangPat p)) = isLiftedLPat p
+isLiftedLPat (L _ (AsPat _ p)) = isLiftedLPat p
+isLiftedLPat (L _ (TuplePat _ Unboxed _)) = False
+isLiftedLPat (L _ (VarPat {})) = False
+isLiftedLPat (L _ (WildPat {})) = False
+isLiftedLPat _ = True
+
isIrrefutableHsPat :: OutputableBndr id => LPat id -> Bool
-- (isIrrefutableHsPat p) is true if matching against p cannot fail,
-- in the sense of falling through to the next pattern.
go1 (WildPat {}) = True
go1 (VarPat {}) = True
- go1 (VarPatOut {}) = True
go1 (LazyPat {}) = True
go1 (BangPat pat) = go pat
go1 (CoPat _ pat _) = go1 pat
go1 (ConPatIn {}) = False -- Conservative
go1 (ConPatOut{ pat_con = L _ con, pat_args = details })
- = isProductTyCon (dataConTyCon con)
+ = isJust (tyConSingleDataCon_maybe (dataConTyCon con))
+ -- NB: tyConSingleDataCon_maybe, *not* isProductTyCon, because
+ -- the latter is false of existentials. See Trac #4439
&& all go (hsConPatArgs details)
go1 (LitPat {}) = False
go1 (QuasiQuotePat {}) = urk pat -- Gotten rid of by renamer, before
-- isIrrefutablePat is called
- go1 (TypePat {}) = urk pat
urk pat = pprPanic "isIrrefutableHsPat:" (ppr pat)
hsPatNeedsParens :: Pat a -> Bool
hsPatNeedsParens (WildPat {}) = False
hsPatNeedsParens (VarPat {}) = False
-hsPatNeedsParens (VarPatOut {}) = True
hsPatNeedsParens (LazyPat {}) = False
hsPatNeedsParens (BangPat {}) = False
hsPatNeedsParens (CoPat {}) = True
hsPatNeedsParens (NPat {}) = False
hsPatNeedsParens (NPlusKPat {}) = True
hsPatNeedsParens (QuasiQuotePat {}) = True
-hsPatNeedsParens (TypePat {}) = False
conPatNeedsParens :: HsConDetails a b -> Bool
conPatNeedsParens (PrefixCon args) = not (null args)