2 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
4 \section[HsBinds]{Abstract syntax: top-level bindings and signatures}
6 Datatype for: @HsBinds@, @Bind@, @Sig@, @MonoBinds@.
11 #include "HsVersions.h"
13 import {-# SOURCE #-} HsExpr ( HsExpr, pprExpr,
18 import HsImpExp ( pprHsVar )
20 import HsTypes ( HsType )
21 import PprCore ( {- instance Outputable (Expr a) -} )
25 import PrelNames ( isUnboundName )
26 import NameSet ( NameSet, elemNameSet, nameSetToList )
27 import BasicTypes ( RecFlag(..), FixitySig(..), Activation(..), IPName )
29 import SrcLoc ( SrcLoc )
31 import Class ( DefMeth (..) )
34 %************************************************************************
36 \subsection{Bindings: @HsBinds@}
38 %************************************************************************
40 The following syntax may produce new syntax which is not part of the input,
41 and which is instead a translation of the input to the typechecker.
42 Syntax translations are marked TRANSLATION in comments. New empty
43 productions are useful in development but may not appear in the final
46 Collections of bindings, created by dependency analysis and translation:
49 data HsBinds id -- binders and bindees
51 | ThenBinds (HsBinds id) (HsBinds id)
53 | MonoBind -- A mutually recursive group
55 [Sig id] -- Empty on typechecker output, Type Signatures
58 | IPBinds -- Implcit parameters
59 -- Not allowed at top level
60 [(IPName id, HsExpr id)]
64 nullBinds :: HsBinds id -> Bool
66 nullBinds EmptyBinds = True
67 nullBinds (ThenBinds b1 b2) = nullBinds b1 && nullBinds b2
68 nullBinds (MonoBind b _ _) = nullMonoBinds b
69 nullBinds (IPBinds b) = null b
71 mkMonoBind :: RecFlag -> MonoBinds id -> HsBinds id
72 mkMonoBind _ EmptyMonoBinds = EmptyBinds
73 mkMonoBind is_rec mbinds = MonoBind mbinds [] is_rec
77 instance (OutputableBndr id) => Outputable (HsBinds id) where
78 ppr binds = ppr_binds binds
80 ppr_binds EmptyBinds = empty
81 ppr_binds (ThenBinds binds1 binds2)
82 = ppr_binds binds1 $$ ppr_binds binds2
84 ppr_binds (IPBinds binds)
85 = sep (punctuate semi (map pp_item binds))
87 pp_item (id,rhs) = pprBndr LetBind id <+> equals <+> pprExpr rhs
89 ppr_binds (MonoBind bind sigs is_rec)
95 ppr_isrec = getPprStyle $ \ sty ->
96 if userStyle sty then empty else
98 Recursive -> ptext SLIT("{- rec -}")
99 NonRecursive -> ptext SLIT("{- nonrec -}")
102 %************************************************************************
104 \subsection{Bindings: @MonoBinds@}
106 %************************************************************************
108 Global bindings (where clauses)
114 | AndMonoBinds (MonoBinds id)
117 | FunMonoBind id -- Used for both functions f x = e
118 -- and variables f = \x -> e
119 -- Reason: the Match stuff lets us have an optional
120 -- result type sig f :: a->a = ...mentions a...
122 -- This also means that instance decls can only have
123 -- FunMonoBinds, so if you change this, you'll need to
124 -- change e.g. rnMethodBinds
125 Bool -- True => infix declaration
129 | PatMonoBind (Pat id) -- The pattern is never a simple variable;
130 -- That case is done by FunMonoBind
134 | VarMonoBind id -- TRANSLATION
137 | AbsBinds -- Binds abstraction; TRANSLATION
138 [TyVar] -- Type variables
140 [([TyVar], id, id)] -- (type variables, polymorphic, momonmorphic) triples
141 NameSet -- Set of *polymorphic* variables that have an INLINE pragma
142 (MonoBinds id) -- The "business end"
144 -- Creates bindings for *new* (polymorphic, overloaded) locals
145 -- in terms of *old* (monomorphic, non-overloaded) ones.
147 -- See section 9 of static semantics paper for more details.
148 -- (You can get a PhD for explaining the True Meaning
149 -- of this last construct.)
161 f1p = /\ tvs -> \ [d1,d2] -> letrec DBINDS and BIND
164 gp = ...same again, with gm instead of fm
166 This is a pretty bad translation, because it duplicates all the bindings.
167 So the desugarer tries to do a better job:
169 fp = /\ [a,b] -> \ [d1,d2] -> case tp [a,b] [d1,d2] of
173 tp = /\ [a,b] -> \ [d1,d2] -> letrec DBINDS and BIND
177 -- We keep the invariant that a MonoBinds is only empty
178 -- if it is exactly EmptyMonoBinds
180 nullMonoBinds :: MonoBinds id -> Bool
181 nullMonoBinds EmptyMonoBinds = True
182 nullMonoBinds other_monobind = False
184 andMonoBinds :: MonoBinds id -> MonoBinds id -> MonoBinds id
185 andMonoBinds EmptyMonoBinds mb = mb
186 andMonoBinds mb EmptyMonoBinds = mb
187 andMonoBinds mb1 mb2 = AndMonoBinds mb1 mb2
189 andMonoBindList :: [MonoBinds id] -> MonoBinds id
190 andMonoBindList binds
193 loop1 [] = EmptyMonoBinds
194 loop1 (EmptyMonoBinds : binds) = loop1 binds
195 loop1 (b:bs) = loop2 b bs
199 loop2 acc (EmptyMonoBinds : bs) = loop2 acc bs
200 loop2 acc (b:bs) = loop2 (acc `AndMonoBinds` b) bs
205 instance OutputableBndr id => Outputable (MonoBinds id) where
206 ppr mbind = ppr_monobind mbind
209 ppr_monobind :: OutputableBndr id => MonoBinds id -> SDoc
210 ppr_monobind EmptyMonoBinds = empty
211 ppr_monobind (AndMonoBinds binds1 binds2)
212 = ppr_monobind binds1 $$ ppr_monobind binds2
214 ppr_monobind (PatMonoBind pat grhss locn) = pprPatBind pat grhss
215 ppr_monobind (FunMonoBind fun inf matches locn) = pprFunBind fun matches
216 -- ToDo: print infix if appropriate
218 ppr_monobind (VarMonoBind name expr)
219 = sep [pprBndr LetBind name <+> equals, nest 4 (pprExpr expr)]
221 ppr_monobind (AbsBinds tyvars dictvars exports inlines val_binds)
222 = sep [ptext SLIT("AbsBinds"),
223 brackets (interpp'SP tyvars),
224 brackets (interpp'SP dictvars),
225 brackets (sep (punctuate comma (map ppr exports))),
226 brackets (interpp'SP (nameSetToList inlines))]
228 nest 4 ( vcat [pprBndr LetBind x | (_,x,_) <- exports]
229 -- Print type signatures
234 %************************************************************************
236 \subsection{@Sig@: type signatures and value-modifying user pragmas}
238 %************************************************************************
240 It is convenient to lump ``value-modifying'' user-pragmas (e.g.,
241 ``specialise this function to these four types...'') in with type
242 signatures. Then all the machinery to move them into place, etc.,
247 = Sig name -- a bog-std type signature
251 | ClassOpSig name -- Selector name
252 (DefMeth name) -- Default-method info
253 -- See "THE NAMING STORY" in HsDecls
257 | SpecSig name -- specialise a function or datatype ...
258 (HsType name) -- ... to these types
261 | InlineSig Bool -- True <=> INLINE f, False <=> NOINLINE f
262 name -- Function name
263 Activation -- When inlining is *active*
266 | SpecInstSig (HsType name) -- (Class tys); should be a specialisation of the
267 -- current instance decl
270 | FixSig (FixitySig name) -- Fixity declaration
274 okBindSig :: NameSet -> Sig Name -> Bool
275 okBindSig ns (ClassOpSig _ _ _ _) = False
276 okBindSig ns sig = sigForThisGroup ns sig
278 okClsDclSig :: Sig Name -> Bool
279 okClsDclSig (Sig _ _ _) = False
280 okClsDclSig (SpecInstSig _ _) = False
281 okClsDclSig sig = True -- All others OK
283 okInstDclSig :: NameSet -> Sig Name -> Bool
284 okInstDclSig ns (Sig _ _ _) = False
285 okInstDclSig ns (FixSig _) = False
286 okInstDclSig ns (SpecInstSig _ _) = True
287 okInstDclSig ns sig = sigForThisGroup ns sig
289 sigForThisGroup ns sig
290 = case sigName sig of
292 Just n | isUnboundName n -> True -- Don't complain about an unbound name again
293 | otherwise -> n `elemNameSet` ns
295 sigName :: Sig name -> Maybe name
296 sigName (Sig n _ _) = Just n
297 sigName (ClassOpSig n _ _ _) = Just n
298 sigName (SpecSig n _ _) = Just n
299 sigName (InlineSig _ n _ _) = Just n
300 sigName (FixSig (FixitySig n _ _)) = Just n
301 sigName other = Nothing
303 isFixitySig :: Sig name -> Bool
304 isFixitySig (FixSig _) = True
305 isFixitySig _ = False
307 isClassOpSig :: Sig name -> Bool
308 isClassOpSig (ClassOpSig _ _ _ _) = True
309 isClassOpSig _ = False
311 isPragSig :: Sig name -> Bool
312 -- Identifies pragmas
313 isPragSig (SpecSig _ _ _) = True
314 isPragSig (InlineSig _ _ _ _) = True
315 isPragSig (SpecInstSig _ _) = True
316 isPragSig other = False
320 hsSigDoc (Sig _ _ loc) = (ptext SLIT("type signature"),loc)
321 hsSigDoc (ClassOpSig _ _ _ loc) = (ptext SLIT("class-method type signature"), loc)
322 hsSigDoc (SpecSig _ _ loc) = (ptext SLIT("SPECIALISE pragma"),loc)
323 hsSigDoc (InlineSig True _ _ loc) = (ptext SLIT("INLINE pragma"),loc)
324 hsSigDoc (InlineSig False _ _ loc) = (ptext SLIT("NOINLINE pragma"),loc)
325 hsSigDoc (SpecInstSig _ loc) = (ptext SLIT("SPECIALISE instance pragma"),loc)
326 hsSigDoc (FixSig (FixitySig _ _ loc)) = (ptext SLIT("fixity declaration"), loc)
330 instance (Outputable name) => Outputable (Sig name) where
331 ppr sig = ppr_sig sig
333 ppr_sig :: Outputable name => Sig name -> SDoc
334 ppr_sig (Sig var ty _)
335 = sep [ppr var <+> dcolon, nest 4 (ppr ty)]
337 ppr_sig (ClassOpSig var dm ty _)
338 = sep [ pprHsVar var <+> dcolon,
340 nest 4 (pp_dm_comment) ]
343 DefMeth _ -> equals -- Default method indicator
344 GenDefMeth -> semi -- Generic method indicator
345 NoDefMeth -> empty -- No Method at all
346 pp_dm_comment = case dm of
347 DefMeth _ -> text "{- has default method -}"
348 GenDefMeth -> text "{- has generic method -}"
349 NoDefMeth -> empty -- No Method at all
351 ppr_sig (SpecSig var ty _)
352 = sep [ hsep [text "{-# SPECIALIZE", ppr var, dcolon],
353 nest 4 (ppr ty <+> text "#-}")
356 ppr_sig (InlineSig True var phase _)
357 = hsep [text "{-# INLINE", ppr phase, ppr var, text "#-}"]
359 ppr_sig (InlineSig False var phase _)
360 = hsep [text "{-# NOINLINE", ppr phase, ppr var, text "#-}"]
362 ppr_sig (SpecInstSig ty _)
363 = hsep [text "{-# SPECIALIZE instance", ppr ty, text "#-}"]
365 ppr_sig (FixSig fix_sig) = ppr fix_sig
368 Checking for distinct signatures; oh, so boring
372 eqHsSig :: Sig Name -> Sig Name -> Bool
373 eqHsSig (Sig n1 _ _) (Sig n2 _ _) = n1 == n2
374 eqHsSig (InlineSig b1 n1 _ _)(InlineSig b2 n2 _ _) = b1 == b2 && n1 == n2
376 eqHsSig (SpecInstSig ty1 _) (SpecInstSig ty2 _) = ty1 == ty2
377 eqHsSig (SpecSig n1 ty1 _) (SpecSig n2 ty2 _) =
378 -- may have many specialisations for one value;
379 -- but not ones that are exactly the same...
380 (n1 == n2) && (ty1 == ty2)
382 eqHsSig _other1 _other2 = False