2 % (c) The GRASP/AQUA Project, Glasgow University, 1993-1998
4 %************************************************************************
6 \section[HsCore]{Core-syntax unfoldings in Haskell interface files}
8 %************************************************************************
10 We could either use this, or parameterise @GenCoreExpr@ on @Types@ and
11 @TyVars@ as well. Currently trying the former... MEGA SIGH.
15 module IfaceType, -- Re-export all this
17 IfaceDecl(..), IfaceClassOp(..), IfaceConDecl(..), IfaceConDecls(..),
18 IfaceExpr(..), IfaceAlt, IfaceNote(..),
19 IfaceBinding(..), IfaceConAlt(..), IfaceIdInfo(..),
20 IfaceInfoItem(..), IfaceRule(..), IfaceInst(..),
25 -- Converting things to IfaceSyn
26 tyThingToIfaceDecl, instanceToIfaceInst, coreRuleToIfaceRule,
29 IfaceEq(..), (&&&), bool, eqListBy, eqMaybeBy,
30 eqIfDecl, eqIfInst, eqIfRule,
33 pprIfaceExpr, pprIfaceDecl, pprIfaceDeclHead
36 #include "HsVersions.h"
41 import FunDeps ( pprFundeps )
42 import NewDemand ( StrictSig, pprIfaceStrictSig )
43 import TcType ( deNoteType )
44 import Type ( TyThing(..), splitForAllTys, funResultTy )
45 import InstEnv ( Instance(..), OverlapFlag )
46 import Id ( Id, idName, idType, idInfo, idArity, isDataConWorkId_maybe, isFCallId_maybe )
47 import NewDemand ( isTopSig )
48 import IdInfo ( IdInfo, CafInfo(..), WorkerInfo(..),
49 arityInfo, cafInfo, newStrictnessInfo,
50 workerInfo, unfoldingInfo, inlinePragInfo )
51 import TyCon ( TyCon, ArgVrcs, AlgTyConRhs(..), isRecursiveTyCon, isForeignTyCon,
52 isSynTyCon, isAlgTyCon, isPrimTyCon, isFunTyCon,
53 isTupleTyCon, tupleTyConBoxity, tyConStupidTheta,
54 tyConHasGenerics, tyConArgVrcs, getSynTyConDefn,
55 tyConArity, tyConTyVars, algTyConRhs, tyConExtName )
56 import DataCon ( dataConName, dataConSig, dataConFieldLabels, dataConStrictMarks,
57 dataConTyCon, dataConIsInfix, isVanillaDataCon )
58 import Class ( FunDep, DefMeth, classExtraBigSig, classTyCon )
59 import OccName ( OccName, OccEnv, emptyOccEnv,
60 lookupOccEnv, extendOccEnv, parenSymOcc,
61 OccSet, unionOccSets, unitOccSet )
62 import Name ( Name, NamedThing(..), nameOccName, isExternalName )
63 import CostCentre ( CostCentre, pprCostCentreCore )
64 import Literal ( Literal )
65 import ForeignCall ( ForeignCall )
66 import TysPrim ( alphaTyVars )
67 import BasicTypes ( Arity, Activation(..), StrictnessMark,
68 RecFlag(..), boolToRecFlag, Boxity(..),
72 import Maybes ( catMaybes )
73 import Util ( lengthIs )
76 infix 4 `eqIfExt`, `eqIfIdInfo`, `eqIfType`
80 %************************************************************************
82 Data type declarations
84 %************************************************************************
88 = IfaceId { ifName :: OccName,
90 ifIdInfo :: IfaceIdInfo }
92 | IfaceData { ifName :: OccName, -- Type constructor
93 ifTyVars :: [IfaceTvBndr], -- Type variables
94 ifCtxt :: IfaceContext, -- The "stupid theta"
95 ifCons :: IfaceConDecls, -- Includes new/data info
96 ifRec :: RecFlag, -- Recursive or not?
98 ifGeneric :: Bool -- True <=> generic converter functions available
99 } -- We need this for imported data decls, since the
100 -- imported modules may have been compiled with
101 -- different flags to the current compilation unit
103 | IfaceSyn { ifName :: OccName, -- Type constructor
104 ifTyVars :: [IfaceTvBndr], -- Type variables
106 ifSynRhs :: IfaceType -- synonym expansion
109 | IfaceClass { ifCtxt :: IfaceContext, -- Context...
110 ifName :: OccName, -- Name of the class
111 ifTyVars :: [IfaceTvBndr], -- Type variables
112 ifFDs :: [FunDep OccName], -- Functional dependencies
113 ifSigs :: [IfaceClassOp], -- Method signatures
114 ifRec :: RecFlag, -- Is newtype/datatype associated with the class recursive?
115 ifVrcs :: ArgVrcs -- ... and what are its argument variances ...
118 | IfaceForeign { ifName :: OccName, -- Needs expanding when we move beyond .NET
119 ifExtName :: Maybe FastString }
121 data IfaceClassOp = IfaceClassOp OccName DefMeth IfaceType
122 -- Nothing => no default method
123 -- Just False => ordinary polymorphic default method
124 -- Just True => generic default method
127 = IfAbstractTyCon -- No info
128 | IfDataTyCon [IfaceConDecl] -- data type decls
129 | IfNewTyCon IfaceConDecl -- newtype decls
131 visibleIfConDecls :: IfaceConDecls -> [IfaceConDecl]
132 visibleIfConDecls IfAbstractTyCon = []
133 visibleIfConDecls (IfDataTyCon cs) = cs
134 visibleIfConDecls (IfNewTyCon c) = [c]
138 ifConOcc :: OccName, -- Constructor name
139 ifConInfix :: Bool, -- True <=> declared infix
140 ifConArgTys :: [IfaceType], -- Arg types
141 ifConStricts :: [StrictnessMark], -- Empty (meaning all lazy), or 1-1 corresp with arg types
142 ifConFields :: [OccName] } -- ...ditto... (field labels)
144 ifConOcc :: OccName, -- Constructor name
145 ifConTyVars :: [IfaceTvBndr], -- All tyvars
146 ifConCtxt :: IfaceContext, -- Non-stupid context
147 ifConArgTys :: [IfaceType], -- Arg types
148 ifConResTys :: [IfaceType], -- Result type args
149 ifConStricts :: [StrictnessMark] } -- Empty (meaning all lazy), or 1-1 corresp with arg types
152 = IfaceInst { ifInstCls :: IfaceExtName, -- See comments with
153 ifInstTys :: [Maybe IfaceTyCon], -- the defn of Instance
154 ifDFun :: OccName, -- The dfun
155 ifOFlag :: OverlapFlag, -- Overlap flag
156 ifInstOrph :: Maybe OccName } -- See is_orph in defn of Instance
157 -- There's always a separate IfaceDecl for the DFun, which gives
158 -- its IdInfo with its full type and version number.
159 -- The instance declarations taken together have a version number,
160 -- and we don't want that to wobble gratuitously
161 -- If this instance decl is *used*, we'll record a usage on the dfun;
162 -- and if the head does not change it won't be used if it wasn't before
166 ifRuleName :: RuleName,
167 ifActivation :: Activation,
168 ifRuleBndrs :: [IfaceBndr], -- Tyvars and term vars
169 ifRuleHead :: IfaceExtName, -- Head of lhs
170 ifRuleArgs :: [IfaceExpr], -- Args of LHS
171 ifRuleRhs :: IfaceExpr,
172 ifRuleOrph :: Maybe OccName -- Just like IfaceInst
176 = NoInfo -- When writing interface file without -O
177 | HasInfo [IfaceInfoItem] -- Has info, and here it is
179 -- Here's a tricky case:
180 -- * Compile with -O module A, and B which imports A.f
181 -- * Change function f in A, and recompile without -O
182 -- * When we read in old A.hi we read in its IdInfo (as a thunk)
183 -- (In earlier GHCs we used to drop IdInfo immediately on reading,
184 -- but we do not do that now. Instead it's discarded when the
185 -- ModIface is read into the various decl pools.)
186 -- * The version comparsion sees that new (=NoInfo) differs from old (=HasInfo *)
187 -- and so gives a new version.
191 | HsStrictness StrictSig
192 | HsUnfold Activation IfaceExpr
194 | HsWorker IfaceExtName Arity -- Worker, if any see IdInfo.WorkerInfo
195 -- for why we want arity here.
196 -- NB: we need IfaceExtName (not just OccName) because the worker
197 -- can simplify to a function in another module.
198 -- NB: Specialisations and rules come in separately and are
199 -- only later attached to the Id. Partial reason: some are orphans.
201 --------------------------------
204 | IfaceExt IfaceExtName
205 | IfaceType IfaceType
206 | IfaceTuple Boxity [IfaceExpr] -- Saturated; type arguments omitted
207 | IfaceLam IfaceBndr IfaceExpr
208 | IfaceApp IfaceExpr IfaceExpr
209 | IfaceCase IfaceExpr OccName IfaceType [IfaceAlt]
210 | IfaceLet IfaceBinding IfaceExpr
211 | IfaceNote IfaceNote IfaceExpr
213 | IfaceFCall ForeignCall IfaceType
215 data IfaceNote = IfaceSCC CostCentre
216 | IfaceCoerce IfaceType
219 | IfaceCoreNote String
221 type IfaceAlt = (IfaceConAlt, [OccName], IfaceExpr)
222 -- Note: OccName, not IfaceBndr (and same with the case binder)
223 -- We reconstruct the kind/type of the thing from the context
224 -- thus saving bulk in interface files
226 data IfaceConAlt = IfaceDefault
227 | IfaceDataAlt OccName
228 | IfaceTupleAlt Boxity
229 | IfaceLitAlt Literal
232 = IfaceNonRec IfaceIdBndr IfaceExpr
233 | IfaceRec [(IfaceIdBndr, IfaceExpr)]
237 %************************************************************************
239 \subsection[HsCore-print]{Printing Core unfoldings}
241 %************************************************************************
243 ----------------------------- Printing IfaceDecl ------------------------------------
246 instance Outputable IfaceDecl where
249 pprIfaceDecl (IfaceId {ifName = var, ifType = ty, ifIdInfo = info})
250 = sep [ ppr var <+> dcolon <+> ppr ty,
253 pprIfaceDecl (IfaceForeign {ifName = tycon})
254 = hsep [ptext SLIT("foreign import type dotnet"), ppr tycon]
256 pprIfaceDecl (IfaceSyn {ifName = tycon, ifTyVars = tyvars, ifSynRhs = mono_ty, ifVrcs = vrcs})
257 = hang (ptext SLIT("type") <+> pprIfaceDeclHead [] tycon tyvars)
258 4 (vcat [equals <+> ppr mono_ty,
261 pprIfaceDecl (IfaceData {ifName = tycon, ifGeneric = gen, ifCtxt = context,
262 ifTyVars = tyvars, ifCons = condecls,
263 ifRec = isrec, ifVrcs = vrcs})
264 = hang (pp_nd <+> pprIfaceDeclHead context tycon tyvars)
265 4 (vcat [pprVrcs vrcs, pprRec isrec, pprGen gen, pp_condecls tycon condecls])
267 pp_nd = case condecls of
268 IfAbstractTyCon -> ptext SLIT("data")
269 IfDataTyCon _ -> ptext SLIT("data")
270 IfNewTyCon _ -> ptext SLIT("newtype")
272 pprIfaceDecl (IfaceClass {ifCtxt = context, ifName = clas, ifTyVars = tyvars,
273 ifFDs = fds, ifSigs = sigs, ifVrcs = vrcs, ifRec = isrec})
274 = hang (ptext SLIT("class") <+> pprIfaceDeclHead context clas tyvars <+> pprFundeps fds)
275 4 (vcat [pprVrcs vrcs,
279 pprVrcs vrcs = ptext SLIT("Variances") <+> ppr vrcs
280 pprRec isrec = ptext SLIT("RecFlag") <+> ppr isrec
281 pprGen True = ptext SLIT("Generics: yes")
282 pprGen False = ptext SLIT("Generics: no")
284 instance Outputable IfaceClassOp where
285 ppr (IfaceClassOp n dm ty) = ppr n <+> ppr dm <+> dcolon <+> ppr ty
287 pprIfaceDeclHead :: IfaceContext -> OccName -> [IfaceTvBndr] -> SDoc
288 pprIfaceDeclHead context thing tyvars
289 = hsep [pprIfaceContext context, parenSymOcc thing (ppr thing), pprIfaceTvBndrs tyvars]
291 pp_condecls tc IfAbstractTyCon = ptext SLIT("{- abstract -}")
292 pp_condecls tc (IfNewTyCon c) = equals <+> pprIfaceConDecl tc c
293 pp_condecls tc (IfDataTyCon cs) = equals <+> sep (punctuate (ptext SLIT(" |"))
294 (map (pprIfaceConDecl tc) cs))
296 pprIfaceConDecl tc (IfVanillaCon {
297 ifConOcc = name, ifConInfix = is_infix,
298 ifConArgTys = arg_tys,
299 ifConStricts = strs, ifConFields = fields })
300 = sep [ppr name <+> sep (map pprParendIfaceType arg_tys),
301 if is_infix then ptext SLIT("Infix") else empty,
302 if null strs then empty
303 else nest 4 (ptext SLIT("Stricts:") <+> hsep (map ppr strs)),
304 if null fields then empty
305 else nest 4 (ptext SLIT("Fields:") <+> hsep (map ppr fields))]
307 pprIfaceConDecl tc (IfGadtCon {
309 ifConTyVars = tvs, ifConCtxt = ctxt,
310 ifConArgTys = arg_tys, ifConResTys = res_tys,
311 ifConStricts = strs })
312 = sep [ppr name <+> dcolon <+> pprIfaceForAllPart tvs ctxt (ppr con_tau),
313 if null strs then empty
314 else nest 4 (ptext SLIT("Stricts:") <+> hsep (map ppr strs))]
316 con_tau = foldr1 IfaceFunTy (arg_tys ++ [tc_app])
317 tc_app = IfaceTyConApp (IfaceTc (LocalTop tc)) res_tys
318 -- Gruesome, but jsut for debug print
320 instance Outputable IfaceRule where
321 ppr (IfaceRule { ifRuleName = name, ifActivation = act, ifRuleBndrs = bndrs,
322 ifRuleHead = fn, ifRuleArgs = args, ifRuleRhs = rhs })
323 = sep [hsep [doubleQuotes (ftext name), ppr act,
324 ptext SLIT("forall") <+> pprIfaceBndrs bndrs],
325 nest 2 (sep [ppr fn <+> sep (map (pprIfaceExpr parens) args),
326 ptext SLIT("=") <+> ppr rhs])
329 instance Outputable IfaceInst where
330 ppr (IfaceInst {ifDFun = dfun_id, ifOFlag = flag,
331 ifInstCls = cls, ifInstTys = mb_tcs})
332 = hang (ptext SLIT("instance") <+> ppr flag
333 <+> ppr cls <+> brackets (pprWithCommas ppr_mb mb_tcs))
334 2 (equals <+> ppr dfun_id)
337 ppr_mb (Just tc) = ppr tc
341 ----------------------------- Printing IfaceExpr ------------------------------------
344 instance Outputable IfaceExpr where
345 ppr e = pprIfaceExpr noParens e
347 pprIfaceExpr :: (SDoc -> SDoc) -> IfaceExpr -> SDoc
348 -- The function adds parens in context that need
349 -- an atomic value (e.g. function args)
351 pprIfaceExpr add_par (IfaceLcl v) = ppr v
352 pprIfaceExpr add_par (IfaceExt v) = ppr v
353 pprIfaceExpr add_par (IfaceLit l) = ppr l
354 pprIfaceExpr add_par (IfaceFCall cc ty) = braces (ppr cc <+> ppr ty)
355 pprIfaceExpr add_par (IfaceType ty) = char '@' <+> pprParendIfaceType ty
357 pprIfaceExpr add_par app@(IfaceApp _ _) = add_par (pprIfaceApp app [])
358 pprIfaceExpr add_par (IfaceTuple c as) = tupleParens c (interpp'SP as)
360 pprIfaceExpr add_par e@(IfaceLam _ _)
361 = add_par (sep [char '\\' <+> sep (map ppr bndrs) <+> arrow,
362 pprIfaceExpr noParens body])
364 (bndrs,body) = collect [] e
365 collect bs (IfaceLam b e) = collect (b:bs) e
366 collect bs e = (reverse bs, e)
369 pprIfaceExpr add_par (IfaceCase scrut bndr ty [(con, bs, rhs)])
371 = add_par (sep [ptext SLIT("case") <+> char '@' <+> pprParendIfaceType ty <+> pprIfaceExpr noParens scrut <+> ptext SLIT("of")
372 <+> ppr bndr <+> char '{' <+> ppr_con_bs con bs <+> arrow,
373 pprIfaceExpr noParens rhs <+> char '}'])
376 pprIfaceExpr add_par (IfaceCase scrut bndr ty alts)
378 = add_par (sep [ptext SLIT("case") <+> char '@' <+> pprParendIfaceType ty <+> pprIfaceExpr noParens scrut <+> ptext SLIT("of")
379 <+> ppr bndr <+> char '{',
380 nest 2 (sep (map ppr_alt alts)) <+> char '}'])
382 pprIfaceExpr add_par (IfaceLet (IfaceNonRec b rhs) body)
383 = add_par (sep [ptext SLIT("let {"),
384 nest 2 (ppr_bind (b, rhs)),
386 pprIfaceExpr noParens body])
388 pprIfaceExpr add_par (IfaceLet (IfaceRec pairs) body)
389 = add_par (sep [ptext SLIT("letrec {"),
390 nest 2 (sep (map ppr_bind pairs)),
392 pprIfaceExpr noParens body])
394 pprIfaceExpr add_par (IfaceNote note body) = add_par (ppr note <+> pprIfaceExpr parens body)
396 ppr_alt (con, bs, rhs) = sep [ppr_con_bs con bs,
397 arrow <+> pprIfaceExpr noParens rhs]
399 ppr_con_bs (IfaceTupleAlt tup_con) bs = tupleParens tup_con (interpp'SP bs)
400 ppr_con_bs con bs = ppr con <+> hsep (map ppr bs)
402 ppr_bind ((b,ty),rhs) = sep [ppr b <+> dcolon <+> ppr ty,
403 equals <+> pprIfaceExpr noParens rhs]
406 pprIfaceApp (IfaceApp fun arg) args = pprIfaceApp fun (nest 2 (pprIfaceExpr parens arg) : args)
407 pprIfaceApp fun args = sep (pprIfaceExpr parens fun : args)
410 instance Outputable IfaceNote where
411 ppr (IfaceSCC cc) = pprCostCentreCore cc
412 ppr (IfaceCoerce ty) = ptext SLIT("__coerce") <+> pprParendIfaceType ty
413 ppr IfaceInlineCall = ptext SLIT("__inline_call")
414 ppr IfaceInlineMe = ptext SLIT("__inline_me")
415 ppr (IfaceCoreNote s) = ptext SLIT("__core_note") <+> pprHsString (mkFastString s)
417 instance Outputable IfaceConAlt where
418 ppr IfaceDefault = text "DEFAULT"
419 ppr (IfaceLitAlt l) = ppr l
420 ppr (IfaceDataAlt d) = ppr d
421 ppr (IfaceTupleAlt b) = panic "ppr IfaceConAlt"
422 -- IfaceTupleAlt is handled by the case-alternative printer
425 instance Outputable IfaceIdInfo where
427 ppr (HasInfo is) = ptext SLIT("{-") <+> fsep (map ppr_hs_info is) <+> ptext SLIT("-}")
429 ppr_hs_info (HsUnfold prag unf) = sep [ptext SLIT("Unfolding: ") <> ppr prag,
430 parens (pprIfaceExpr noParens unf)]
431 ppr_hs_info (HsArity arity) = ptext SLIT("Arity:") <+> int arity
432 ppr_hs_info (HsStrictness str) = ptext SLIT("Strictness:") <+> pprIfaceStrictSig str
433 ppr_hs_info HsNoCafRefs = ptext SLIT("HasNoCafRefs")
434 ppr_hs_info (HsWorker w a) = ptext SLIT("Worker:") <+> ppr w <+> int a
438 %************************************************************************
440 Converting things to their Iface equivalents
442 %************************************************************************
446 tyThingToIfaceDecl :: (Name -> IfaceExtName) -> TyThing -> IfaceDecl
447 -- Assumption: the thing is already tidied, so that locally-bound names
448 -- (lambdas, for-alls) already have non-clashing OccNames
449 -- Reason: Iface stuff uses OccNames, and the conversion here does
450 -- not do tidying on the way
451 tyThingToIfaceDecl ext (AnId id)
452 = IfaceId { ifName = getOccName id,
453 ifType = toIfaceType ext (idType id),
456 info = case toIfaceIdInfo ext (idInfo id) of
458 items -> HasInfo items
460 tyThingToIfaceDecl ext (AClass clas)
461 = IfaceClass { ifCtxt = toIfaceContext ext sc_theta,
462 ifName = getOccName clas,
463 ifTyVars = toIfaceTvBndrs clas_tyvars,
464 ifFDs = map toIfaceFD clas_fds,
465 ifSigs = map toIfaceClassOp op_stuff,
466 ifRec = boolToRecFlag (isRecursiveTyCon tycon),
467 ifVrcs = tyConArgVrcs tycon }
469 (clas_tyvars, clas_fds, sc_theta, _, op_stuff) = classExtraBigSig clas
470 tycon = classTyCon clas
472 toIfaceClassOp (sel_id, def_meth)
473 = ASSERT(sel_tyvars == clas_tyvars)
474 IfaceClassOp (getOccName sel_id) def_meth (toIfaceType ext op_ty)
476 -- Be careful when splitting the type, because of things
477 -- like class Foo a where
478 -- op :: (?x :: String) => a -> a
479 -- and class Baz a where
480 -- op :: (Ord a) => a -> a
481 (sel_tyvars, rho_ty) = splitForAllTys (idType sel_id)
482 op_ty = funResultTy rho_ty
484 toIfaceFD (tvs1, tvs2) = (map getOccName tvs1, map getOccName tvs2)
486 tyThingToIfaceDecl ext (ATyCon tycon)
488 = IfaceSyn { ifName = getOccName tycon,
489 ifTyVars = toIfaceTvBndrs tyvars,
490 ifVrcs = tyConArgVrcs tycon,
491 ifSynRhs = toIfaceType ext syn_ty }
494 = IfaceData { ifName = getOccName tycon,
495 ifTyVars = toIfaceTvBndrs tyvars,
496 ifCtxt = toIfaceContext ext (tyConStupidTheta tycon),
497 ifCons = ifaceConDecls (algTyConRhs tycon),
498 ifRec = boolToRecFlag (isRecursiveTyCon tycon),
499 ifVrcs = tyConArgVrcs tycon,
500 ifGeneric = tyConHasGenerics tycon }
502 | isForeignTyCon tycon
503 = IfaceForeign { ifName = getOccName tycon,
504 ifExtName = tyConExtName tycon }
506 | isPrimTyCon tycon || isFunTyCon tycon
507 -- Needed in GHCi for ':info Int#', for example
508 = IfaceData { ifName = getOccName tycon,
509 ifTyVars = toIfaceTvBndrs (take (tyConArity tycon) alphaTyVars),
511 ifCons = IfAbstractTyCon,
513 ifRec = NonRecursive,
514 ifVrcs = tyConArgVrcs tycon }
516 | otherwise = pprPanic "toIfaceDecl" (ppr tycon)
518 tyvars = tyConTyVars tycon
519 (_, syn_ty) = getSynTyConDefn tycon
521 ifaceConDecls (NewTyCon { data_con = con }) = IfNewTyCon (ifaceConDecl con)
522 ifaceConDecls (DataTyCon { data_cons = cons }) = IfDataTyCon (map ifaceConDecl cons)
523 ifaceConDecls AbstractTyCon = IfAbstractTyCon
524 -- The last case happens when a TyCon has been trimmed during tidying
525 -- Furthermore, tyThingToIfaceDecl is also used
526 -- in TcRnDriver for GHCi, when browsing a module, in which case the
527 -- AbstractTyCon case is perfectly sensible.
529 ifaceConDecl data_con
530 | isVanillaDataCon data_con
531 = IfVanillaCon {ifConOcc = getOccName (dataConName data_con),
532 ifConInfix = dataConIsInfix data_con,
533 ifConArgTys = map (toIfaceType ext) arg_tys,
534 ifConStricts = strict_marks,
535 ifConFields = map getOccName field_labels }
537 = IfGadtCon { ifConOcc = getOccName (dataConName data_con),
538 ifConTyVars = toIfaceTvBndrs tyvars,
539 ifConCtxt = toIfaceContext ext theta,
540 ifConArgTys = map (toIfaceType ext) arg_tys,
541 ifConResTys = map (toIfaceType ext) res_tys,
542 ifConStricts = strict_marks }
544 (tyvars, theta, arg_tys, _, res_tys) = dataConSig data_con
545 field_labels = dataConFieldLabels data_con
546 strict_marks = dataConStrictMarks data_con
548 tyThingToIfaceDecl ext (ADataCon dc)
549 = pprPanic "toIfaceDecl" (ppr dc) -- Should be trimmed out earlier
552 --------------------------
553 instanceToIfaceInst :: (Name -> IfaceExtName) -> Instance -> IfaceInst
554 instanceToIfaceInst ext_lhs ispec@(Instance { is_dfun = dfun_id, is_flag = oflag,
555 is_cls = cls, is_tcs = mb_tcs,
557 = IfaceInst { ifDFun = getOccName dfun_id,
559 ifInstCls = ext_lhs cls,
560 ifInstTys = map do_rough mb_tcs,
563 do_rough Nothing = Nothing
564 do_rough (Just n) = Just (toIfaceTyCon_name ext_lhs n)
566 --------------------------
567 toIfaceIdInfo :: (Name -> IfaceExtName) -> IdInfo -> [IfaceInfoItem]
568 toIfaceIdInfo ext id_info
569 = catMaybes [arity_hsinfo, caf_hsinfo, strict_hsinfo,
570 wrkr_hsinfo, unfold_hsinfo]
572 ------------ Arity --------------
573 arity_info = arityInfo id_info
574 arity_hsinfo | arity_info == 0 = Nothing
575 | otherwise = Just (HsArity arity_info)
577 ------------ Caf Info --------------
578 caf_info = cafInfo id_info
579 caf_hsinfo = case caf_info of
580 NoCafRefs -> Just HsNoCafRefs
583 ------------ Strictness --------------
584 -- No point in explicitly exporting TopSig
585 strict_hsinfo = case newStrictnessInfo id_info of
586 Just sig | not (isTopSig sig) -> Just (HsStrictness sig)
589 ------------ Worker --------------
590 work_info = workerInfo id_info
591 has_worker = case work_info of { HasWorker _ _ -> True; other -> False }
592 wrkr_hsinfo = case work_info of
593 HasWorker work_id wrap_arity ->
594 Just (HsWorker (ext (idName work_id)) wrap_arity)
597 ------------ Unfolding --------------
598 -- The unfolding is redundant if there is a worker
599 unfold_info = unfoldingInfo id_info
600 inline_prag = inlinePragInfo id_info
601 rhs = unfoldingTemplate unfold_info
602 unfold_hsinfo | neverUnfold unfold_info
603 || has_worker = Nothing
604 | otherwise = Just (HsUnfold inline_prag (toIfaceExpr ext rhs))
606 --------------------------
607 coreRuleToIfaceRule :: (Name -> IfaceExtName) -- For the LHS names
608 -> (Name -> IfaceExtName) -- For the RHS names
609 -> CoreRule -> IfaceRule
610 coreRuleToIfaceRule ext_lhs ext_rhs (BuiltinRule { ru_fn = fn})
611 = pprTrace "toHsRule: builtin" (ppr fn) $
612 bogusIfaceRule (mkIfaceExtName fn)
614 coreRuleToIfaceRule ext_lhs ext_rhs
615 (Rule { ru_name = name, ru_fn = fn, ru_act = act, ru_bndrs = bndrs,
616 ru_args = args, ru_rhs = rhs, ru_orph = orph })
617 = IfaceRule { ifRuleName = name, ifActivation = act,
618 ifRuleBndrs = map (toIfaceBndr ext_lhs) bndrs,
619 ifRuleHead = ext_lhs fn,
620 ifRuleArgs = map do_arg args,
621 ifRuleRhs = toIfaceExpr ext_rhs rhs,
624 -- For type args we must remove synonyms from the outermost
625 -- level. Reason: so that when we read it back in we'll
626 -- construct the same ru_rough field as we have right now;
628 do_arg (Type ty) = IfaceType (toIfaceType ext_lhs (deNoteType ty))
629 do_arg arg = toIfaceExpr ext_lhs arg
631 bogusIfaceRule :: IfaceExtName -> IfaceRule
632 bogusIfaceRule id_name
633 = IfaceRule { ifRuleName = FSLIT("bogus"), ifActivation = NeverActive,
634 ifRuleBndrs = [], ifRuleHead = id_name, ifRuleArgs = [],
635 ifRuleRhs = IfaceExt id_name, ifRuleOrph = Nothing }
637 ---------------------
638 toIfaceExpr :: (Name -> IfaceExtName) -> CoreExpr -> IfaceExpr
639 toIfaceExpr ext (Var v) = toIfaceVar ext v
640 toIfaceExpr ext (Lit l) = IfaceLit l
641 toIfaceExpr ext (Type ty) = IfaceType (toIfaceType ext ty)
642 toIfaceExpr ext (Lam x b) = IfaceLam (toIfaceBndr ext x) (toIfaceExpr ext b)
643 toIfaceExpr ext (App f a) = toIfaceApp ext f [a]
645 toIfaceExpr ext (Case s x ty as) = IfaceCase (toIfaceExpr ext s) (getOccName x) (toIfaceType ext ty) (map (toIfaceAlt ext) as)
646 toIfaceExpr ext (Let b e) = IfaceLet (toIfaceBind ext b) (toIfaceExpr ext e)
647 toIfaceExpr ext (Note n e) = IfaceNote (toIfaceNote ext n) (toIfaceExpr ext e)
649 ---------------------
650 toIfaceNote ext (SCC cc) = IfaceSCC cc
651 toIfaceNote ext (Coerce t1 _) = IfaceCoerce (toIfaceType ext t1)
652 toIfaceNote ext InlineCall = IfaceInlineCall
653 toIfaceNote ext InlineMe = IfaceInlineMe
654 toIfaceNote ext (CoreNote s) = IfaceCoreNote s
656 ---------------------
657 toIfaceBind ext (NonRec b r) = IfaceNonRec (toIfaceIdBndr ext b) (toIfaceExpr ext r)
658 toIfaceBind ext (Rec prs) = IfaceRec [(toIfaceIdBndr ext b, toIfaceExpr ext r) | (b,r) <- prs]
660 ---------------------
661 toIfaceAlt ext (c,bs,r) = (toIfaceCon c, map getOccName bs, toIfaceExpr ext r)
663 ---------------------
664 toIfaceCon (DataAlt dc) | isTupleTyCon tc = IfaceTupleAlt (tupleTyConBoxity tc)
665 | otherwise = IfaceDataAlt (getOccName dc)
669 toIfaceCon (LitAlt l) = IfaceLitAlt l
670 toIfaceCon DEFAULT = IfaceDefault
672 ---------------------
673 toIfaceApp ext (App f a) as = toIfaceApp ext f (a:as)
674 toIfaceApp ext (Var v) as
675 = case isDataConWorkId_maybe v of
676 -- We convert the *worker* for tuples into IfaceTuples
677 Just dc | isTupleTyCon tc && saturated
678 -> IfaceTuple (tupleTyConBoxity tc) tup_args
680 val_args = dropWhile isTypeArg as
681 saturated = val_args `lengthIs` idArity v
682 tup_args = map (toIfaceExpr ext) val_args
685 other -> mkIfaceApps ext (toIfaceVar ext v) as
687 toIfaceApp ext e as = mkIfaceApps ext (toIfaceExpr ext e) as
689 mkIfaceApps ext f as = foldl (\f a -> IfaceApp f (toIfaceExpr ext a)) f as
691 ---------------------
692 toIfaceVar :: (Name -> IfaceExtName) -> Id -> IfaceExpr
694 | Just fcall <- isFCallId_maybe v = IfaceFCall fcall (toIfaceType ext (idType v))
695 -- Foreign calls have special syntax
696 | isExternalName name = IfaceExt (ext name)
697 | otherwise = IfaceLcl (nameOccName name)
703 %************************************************************************
705 Equality, for interface file version generaion only
707 %************************************************************************
709 Equality over IfaceSyn returns an IfaceEq, not a Bool. The new constructor is
710 EqBut, which gives the set of *locally-defined* things whose version must be equal
711 for the whole thing to be equal. So the key function is eqIfExt, which compares
714 Of course, equality is also done modulo alpha conversion.
718 = Equal -- Definitely exactly the same
719 | NotEqual -- Definitely different
720 | EqBut OccSet -- The same provided these local things have not changed
722 bool :: Bool -> IfaceEq
724 bool False = NotEqual
726 zapEq :: IfaceEq -> IfaceEq -- Used to forget EqBut information
727 zapEq (EqBut _) = Equal
730 (&&&) :: IfaceEq -> IfaceEq -> IfaceEq
732 NotEqual &&& x = NotEqual
733 EqBut occs &&& Equal = EqBut occs
734 EqBut occs &&& NotEqual = NotEqual
735 EqBut occs1 &&& EqBut occs2 = EqBut (occs1 `unionOccSets` occs2)
737 ---------------------
738 eqIfExt :: IfaceExtName -> IfaceExtName -> IfaceEq
739 -- This function is the core of the EqBut stuff
740 eqIfExt (ExtPkg mod1 occ1) (ExtPkg mod2 occ2) = bool (mod1==mod2 && occ1==occ2)
741 eqIfExt (HomePkg mod1 occ1 v1) (HomePkg mod2 occ2 v2) = bool (mod1==mod2 && occ1==occ2 && v1==v2)
742 eqIfExt (LocalTop occ1) (LocalTop occ2) | occ1 == occ2 = EqBut (unitOccSet occ1)
743 eqIfExt (LocalTopSub occ1 p1) (LocalTop occ2) | occ1 == occ2 = EqBut (unitOccSet p1)
744 eqIfExt (LocalTopSub occ1 p1) (LocalTopSub occ2 _) | occ1 == occ2 = EqBut (unitOccSet p1)
745 eqIfExt n1 n2 = NotEqual
750 ---------------------
751 eqIfDecl :: IfaceDecl -> IfaceDecl -> IfaceEq
752 eqIfDecl (IfaceId s1 t1 i1) (IfaceId s2 t2 i2)
753 = bool (s1 == s2) &&& (t1 `eqIfType` t2) &&& (i1 `eqIfIdInfo` i2)
755 eqIfDecl d1@(IfaceForeign {}) d2@(IfaceForeign {})
756 = bool (ifName d1 == ifName d2 && ifExtName d1 == ifExtName d2)
758 eqIfDecl d1@(IfaceData {}) d2@(IfaceData {})
759 = bool (ifName d1 == ifName d2 &&
760 ifRec d1 == ifRec d2 &&
761 ifVrcs d1 == ifVrcs d2 &&
762 ifGeneric d1 == ifGeneric d2) &&&
763 eqWith (ifTyVars d1) (ifTyVars d2) (\ env ->
764 eq_ifContext env (ifCtxt d1) (ifCtxt d2) &&&
765 eq_hsCD env (ifCons d1) (ifCons d2)
767 -- The type variables of the data type do not scope
768 -- over the constructors (any more), but they do scope
769 -- over the stupid context in the IfaceConDecls
771 eqIfDecl d1@(IfaceSyn {}) d2@(IfaceSyn {})
772 = bool (ifName d1 == ifName d2) &&&
773 eqWith (ifTyVars d1) (ifTyVars d2) (\ env ->
774 eq_ifType env (ifSynRhs d1) (ifSynRhs d2)
777 eqIfDecl d1@(IfaceClass {}) d2@(IfaceClass {})
778 = bool (ifName d1 == ifName d2 &&
779 ifRec d1 == ifRec d2 &&
780 ifVrcs d1 == ifVrcs d2) &&&
781 eqWith (ifTyVars d1) (ifTyVars d2) (\ env ->
782 eq_ifContext env (ifCtxt d1) (ifCtxt d2) &&&
783 eqListBy (eq_hsFD env) (ifFDs d1) (ifFDs d2) &&&
784 eqListBy (eq_cls_sig env) (ifSigs d1) (ifSigs d2)
787 eqIfDecl _ _ = NotEqual -- default case
790 eqWith :: [IfaceTvBndr] -> [IfaceTvBndr] -> (EqEnv -> IfaceEq) -> IfaceEq
791 eqWith = eq_ifTvBndrs emptyEqEnv
793 -----------------------
794 eqIfInst d1 d2 = bool (ifDFun d1 == ifDFun d2)
795 -- All other changes are handled via the version info on the dfun
797 eqIfRule (IfaceRule n1 a1 bs1 f1 es1 rhs1 o1)
798 (IfaceRule n2 a2 bs2 f2 es2 rhs2 o2)
799 = bool (n1==n2 && a1==a2 && o1 == o2) &&&
801 eq_ifBndrs emptyEqEnv bs1 bs2 (\env ->
802 zapEq (eqListBy (eq_ifaceExpr env) es1 es2) &&&
803 -- zapEq: for the LHSs, ignore the EqBut part
804 eq_ifaceExpr env rhs1 rhs2)
806 eq_hsCD env (IfDataTyCon c1) (IfDataTyCon c2)
807 = eqListBy (eq_ConDecl env) c1 c2
809 eq_hsCD env (IfNewTyCon c1) (IfNewTyCon c2) = eq_ConDecl env c1 c2
810 eq_hsCD env IfAbstractTyCon IfAbstractTyCon = Equal
811 eq_hsCD env d1 d2 = NotEqual
813 eq_ConDecl env c1@(IfVanillaCon {}) c2@(IfVanillaCon {})
814 = bool (ifConOcc c1 == ifConOcc c2 &&
815 ifConInfix c1 == ifConInfix c2 &&
816 ifConStricts c1 == ifConStricts c2 &&
817 ifConFields c1 == ifConFields c2) &&&
818 eq_ifTypes env (ifConArgTys c1) (ifConArgTys c2)
820 eq_ConDecl env c1@(IfGadtCon {}) c2@(IfGadtCon {})
821 = bool (ifConOcc c1 == ifConOcc c2 &&
822 ifConStricts c1 == ifConStricts c2) &&&
823 eq_ifTvBndrs env (ifConTyVars c1) (ifConTyVars c2) (\ env ->
824 eq_ifContext env (ifConCtxt c1) (ifConCtxt c2) &&&
825 eq_ifTypes env (ifConResTys c1) (ifConResTys c2) &&&
826 eq_ifTypes env (ifConArgTys c1) (ifConArgTys c2))
828 eq_ConDecl env c1 c2 = NotEqual
830 eq_hsFD env (ns1,ms1) (ns2,ms2)
831 = eqListBy (eqIfOcc env) ns1 ns2 &&& eqListBy (eqIfOcc env) ms1 ms2
833 eq_cls_sig env (IfaceClassOp n1 dm1 ty1) (IfaceClassOp n2 dm2 ty2)
834 = bool (n1==n2 && dm1 == dm2) &&& eq_ifType env ty1 ty2
840 eqIfIdInfo NoInfo NoInfo = Equal
841 eqIfIdInfo (HasInfo is1) (HasInfo is2) = eqListBy eq_item is1 is2
842 eqIfIdInfo i1 i2 = NotEqual
844 eq_item (HsArity a1) (HsArity a2) = bool (a1 == a2)
845 eq_item (HsStrictness s1) (HsStrictness s2) = bool (s1 == s2)
846 eq_item (HsUnfold a1 u1) (HsUnfold a2 u2) = bool (a1 == a2) &&& eq_ifaceExpr emptyEqEnv u1 u2
847 eq_item HsNoCafRefs HsNoCafRefs = Equal
848 eq_item (HsWorker wkr1 a1) (HsWorker wkr2 a2) = bool (a1==a2) &&& (wkr1 `eqIfExt` wkr2)
849 eq_item _ _ = NotEqual
852 eq_ifaceExpr :: EqEnv -> IfaceExpr -> IfaceExpr -> IfaceEq
853 eq_ifaceExpr env (IfaceLcl v1) (IfaceLcl v2) = eqIfOcc env v1 v2
854 eq_ifaceExpr env (IfaceExt v1) (IfaceExt v2) = eqIfExt v1 v2
855 eq_ifaceExpr env (IfaceLit l1) (IfaceLit l2) = bool (l1 == l2)
856 eq_ifaceExpr env (IfaceFCall c1 ty1) (IfaceFCall c2 ty2) = bool (c1==c2) &&& eq_ifType env ty1 ty2
857 eq_ifaceExpr env (IfaceType ty1) (IfaceType ty2) = eq_ifType env ty1 ty2
858 eq_ifaceExpr env (IfaceTuple n1 as1) (IfaceTuple n2 as2) = bool (n1==n2) &&& eqListBy (eq_ifaceExpr env) as1 as2
859 eq_ifaceExpr env (IfaceLam b1 body1) (IfaceLam b2 body2) = eq_ifBndr env b1 b2 (\env -> eq_ifaceExpr env body1 body2)
860 eq_ifaceExpr env (IfaceApp f1 a1) (IfaceApp f2 a2) = eq_ifaceExpr env f1 f2 &&& eq_ifaceExpr env a1 a2
861 eq_ifaceExpr env (IfaceNote n1 r1) (IfaceNote n2 r2) = eq_ifaceNote env n1 n2 &&& eq_ifaceExpr env r1 r2
863 eq_ifaceExpr env (IfaceCase s1 b1 ty1 as1) (IfaceCase s2 b2 ty2 as2)
864 = eq_ifaceExpr env s1 s2 &&&
865 eq_ifType env ty1 ty2 &&&
866 eq_ifNakedBndr env b1 b2 (\env -> eqListBy (eq_ifaceAlt env) as1 as2)
868 eq_ifaceAlt env (c1,bs1,r1) (c2,bs2,r2)
869 = bool (eq_ifaceConAlt c1 c2) &&&
870 eq_ifNakedBndrs env bs1 bs2 (\env -> eq_ifaceExpr env r1 r2)
872 eq_ifaceExpr env (IfaceLet (IfaceNonRec b1 r1) x1) (IfaceLet (IfaceNonRec b2 r2) x2)
873 = eq_ifaceExpr env r1 r2 &&& eq_ifIdBndr env b1 b2 (\env -> eq_ifaceExpr env x1 x2)
875 eq_ifaceExpr env (IfaceLet (IfaceRec as1) x1) (IfaceLet (IfaceRec as2) x2)
876 = eq_ifIdBndrs env bs1 bs2 (\env -> eqListBy (eq_ifaceExpr env) rs1 rs2 &&& eq_ifaceExpr env x1 x2)
878 (bs1,rs1) = unzip as1
879 (bs2,rs2) = unzip as2
882 eq_ifaceExpr env _ _ = NotEqual
885 eq_ifaceConAlt :: IfaceConAlt -> IfaceConAlt -> Bool
886 eq_ifaceConAlt IfaceDefault IfaceDefault = True
887 eq_ifaceConAlt (IfaceDataAlt n1) (IfaceDataAlt n2) = n1==n2
888 eq_ifaceConAlt (IfaceTupleAlt c1) (IfaceTupleAlt c2) = c1==c2
889 eq_ifaceConAlt (IfaceLitAlt l1) (IfaceLitAlt l2) = l1==l2
890 eq_ifaceConAlt _ _ = False
893 eq_ifaceNote :: EqEnv -> IfaceNote -> IfaceNote -> IfaceEq
894 eq_ifaceNote env (IfaceSCC c1) (IfaceSCC c2) = bool (c1==c2)
895 eq_ifaceNote env (IfaceCoerce t1) (IfaceCoerce t2) = eq_ifType env t1 t2
896 eq_ifaceNote env IfaceInlineCall IfaceInlineCall = Equal
897 eq_ifaceNote env IfaceInlineMe IfaceInlineMe = Equal
898 eq_ifaceNote env (IfaceCoreNote s1) (IfaceCoreNote s2) = bool (s1==s2)
899 eq_ifaceNote env _ _ = NotEqual
903 ---------------------
904 eqIfType t1 t2 = eq_ifType emptyEqEnv t1 t2
907 eq_ifType env (IfaceTyVar n1) (IfaceTyVar n2) = eqIfOcc env n1 n2
908 eq_ifType env (IfaceAppTy s1 t1) (IfaceAppTy s2 t2) = eq_ifType env s1 s2 &&& eq_ifType env t1 t2
909 eq_ifType env (IfacePredTy st1) (IfacePredTy st2) = eq_ifPredType env st1 st2
910 eq_ifType env (IfaceTyConApp tc1 ts1) (IfaceTyConApp tc2 ts2) = tc1 `eqIfTc` tc2 &&& eq_ifTypes env ts1 ts2
911 eq_ifType env (IfaceForAllTy tv1 t1) (IfaceForAllTy tv2 t2) = eq_ifTvBndr env tv1 tv2 (\env -> eq_ifType env t1 t2)
912 eq_ifType env (IfaceFunTy s1 t1) (IfaceFunTy s2 t2) = eq_ifType env s1 s2 &&& eq_ifType env t1 t2
913 eq_ifType env _ _ = NotEqual
916 eq_ifTypes env = eqListBy (eq_ifType env)
919 eq_ifContext env a b = eqListBy (eq_ifPredType env) a b
922 eq_ifPredType env (IfaceClassP c1 tys1) (IfaceClassP c2 tys2) = c1 `eqIfExt` c2 &&& eq_ifTypes env tys1 tys2
923 eq_ifPredType env (IfaceIParam n1 ty1) (IfaceIParam n2 ty2) = bool (n1 == n2) &&& eq_ifType env ty1 ty2
924 eq_ifPredType env _ _ = NotEqual
927 eqIfTc (IfaceTc tc1) (IfaceTc tc2) = tc1 `eqIfExt` tc2
928 eqIfTc IfaceIntTc IfaceIntTc = Equal
929 eqIfTc IfaceCharTc IfaceCharTc = Equal
930 eqIfTc IfaceBoolTc IfaceBoolTc = Equal
931 eqIfTc IfaceListTc IfaceListTc = Equal
932 eqIfTc IfacePArrTc IfacePArrTc = Equal
933 eqIfTc (IfaceTupTc bx1 ar1) (IfaceTupTc bx2 ar2) = bool (bx1==bx2 && ar1==ar2)
934 eqIfTc _ _ = NotEqual
937 -----------------------------------------------------------
938 Support code for equality checking
939 -----------------------------------------------------------
942 ------------------------------------
943 type EqEnv = OccEnv OccName -- Tracks the mapping from L-variables to R-variables
945 eqIfOcc :: EqEnv -> OccName -> OccName -> IfaceEq
946 eqIfOcc env n1 n2 = case lookupOccEnv env n1 of
947 Just n1 -> bool (n1 == n2)
948 Nothing -> bool (n1 == n2)
950 extendEqEnv :: EqEnv -> OccName -> OccName -> EqEnv
951 extendEqEnv env n1 n2 | n1 == n2 = env
952 | otherwise = extendOccEnv env n1 n2
955 emptyEqEnv = emptyOccEnv
957 ------------------------------------
958 type ExtEnv bndr = EqEnv -> bndr -> bndr -> (EqEnv -> IfaceEq) -> IfaceEq
960 eq_ifNakedBndr :: ExtEnv OccName
961 eq_ifBndr :: ExtEnv IfaceBndr
962 eq_ifTvBndr :: ExtEnv IfaceTvBndr
963 eq_ifIdBndr :: ExtEnv IfaceIdBndr
965 eq_ifNakedBndr env n1 n2 k = k (extendEqEnv env n1 n2)
967 eq_ifBndr env (IfaceIdBndr b1) (IfaceIdBndr b2) k = eq_ifIdBndr env b1 b2 k
968 eq_ifBndr env (IfaceTvBndr b1) (IfaceTvBndr b2) k = eq_ifTvBndr env b1 b2 k
969 eq_ifBndr _ _ _ _ = NotEqual
971 eq_ifTvBndr env (v1, k1) (v2, k2) k = bool (k1 == k2) &&& k (extendEqEnv env v1 v2)
972 eq_ifIdBndr env (v1, t1) (v2, t2) k = eq_ifType env t1 t2 &&& k (extendEqEnv env v1 v2)
974 eq_ifBndrs :: ExtEnv [IfaceBndr]
975 eq_ifIdBndrs :: ExtEnv [IfaceIdBndr]
976 eq_ifTvBndrs :: ExtEnv [IfaceTvBndr]
977 eq_ifNakedBndrs :: ExtEnv [OccName]
978 eq_ifBndrs = eq_bndrs_with eq_ifBndr
979 eq_ifIdBndrs = eq_bndrs_with eq_ifIdBndr
980 eq_ifTvBndrs = eq_bndrs_with eq_ifTvBndr
981 eq_ifNakedBndrs = eq_bndrs_with eq_ifNakedBndr
983 eq_bndrs_with eq env [] [] k = k env
984 eq_bndrs_with eq env (b1:bs1) (b2:bs2) k = eq env b1 b2 (\env -> eq_bndrs_with eq env bs1 bs2 k)
985 eq_bndrs_with eq env _ _ _ = NotEqual
989 eqListBy :: (a->a->IfaceEq) -> [a] -> [a] -> IfaceEq
990 eqListBy eq [] [] = Equal
991 eqListBy eq (x:xs) (y:ys) = eq x y &&& eqListBy eq xs ys
992 eqListBy eq xs ys = NotEqual
994 eqMaybeBy :: (a->a->IfaceEq) -> Maybe a -> Maybe a -> IfaceEq
995 eqMaybeBy eq Nothing Nothing = Equal
996 eqMaybeBy eq (Just x) (Just y) = eq x y
997 eqMaybeBy eq x y = NotEqual