2 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
4 \section[TyCon]{The @TyCon@ datatype}
8 TyCon, ArgVrcs, FieldLabel,
13 AlgTyConRhs(..), visibleDataCons,
15 isFunTyCon, isUnLiftedTyCon, isProductTyCon,
16 isAlgTyCon, isDataTyCon, isSynTyCon, isNewTyCon, isPrimTyCon,
18 isTupleTyCon, isUnboxedTupleTyCon, isBoxedTupleTyCon, tupleTyConBoxity,
19 isRecursiveTyCon, newTyConRep, newTyConRhs, newTyConRhs_maybe, isHiBootTyCon,
21 makeTyConAbstract, isAbstractTyCon,
23 mkForeignTyCon, isForeignTyCon,
38 algTyConRhs, tyConDataCons, tyConDataCons_maybe, tyConFamilySize,
39 tyConFields, tyConSelIds,
42 isClassTyCon, tyConClass_maybe,
44 tyConExtName, -- External name for foreign types
52 #include "HsVersions.h"
54 import {-# SOURCE #-} TypeRep ( Type, PredType )
55 -- Should just be Type(Type), but this fails due to bug present up to
56 -- and including 4.02 involving slurping of hi-boot files. Bug is now fixed.
58 import {-# SOURCE #-} DataCon ( DataCon, isVanillaDataCon )
61 import Var ( TyVar, Id )
62 import Class ( Class )
64 import BasicTypes ( Arity, RecFlag(..), Boxity(..), isBoxed )
65 import Name ( Name, nameUnique, NamedThing(getName) )
66 import PrelNames ( Unique, Uniquable(..) )
67 import Maybes ( orElse )
68 import Util ( equalLength )
73 %************************************************************************
75 \subsection{The data type}
77 %************************************************************************
82 tyConUnique :: Unique,
89 | AlgTyCon { -- Data type, and newtype decls.
90 -- All lifted, all boxed
91 tyConUnique :: Unique,
96 tyConTyVars :: [TyVar], -- Scopes over (a) the [PredType] in AlgTyConRhs.DataTyCon
97 -- (b) the cached types in AlgTyConRhs.NewTyCon
98 -- (c) the types in algTcFields
99 -- But not over the data constructors
102 algTcFields :: [(FieldLabel, Type, Id)],
103 -- Its fields (empty if none):
105 -- * its type (scoped over tby tyConTyVars)
106 -- * record selector (name = field name)
108 algTcStupidTheta :: [PredType], -- The "stupid theta" for the data type
109 -- (always empty for GADTs)
111 algTcRhs :: AlgTyConRhs, -- Data constructors in here
113 algTcRec :: RecFlag, -- Tells whether the data type is part of
114 -- a mutually-recursive group or not
116 hasGenerics :: Bool, -- True <=> generic to/from functions are available
117 -- (in the exports of the data type's source module)
119 algTcClass :: Maybe Class
120 -- Just cl if this tycon came from a class declaration
123 | PrimTyCon { -- Primitive types; cannot be defined in Haskell
124 -- Now includes foreign-imported types
125 tyConUnique :: Unique,
131 primTyConRep :: PrimRep,
132 -- Many primitive tycons are unboxed, but some are
133 -- boxed (represented by pointers). The CgRep tells.
135 isUnLifted :: Bool, -- Most primitive tycons are unlifted,
136 -- but foreign-imported ones may not be
137 tyConExtName :: Maybe FastString -- Just xx for foreign-imported types
141 tyConUnique :: Unique,
145 tyConBoxed :: Boxity,
146 tyConTyVars :: [TyVar],
152 tyConUnique :: Unique,
157 tyConTyVars :: [TyVar], -- Bound tyvars
158 synTyConDefn :: Type, -- Right-hand side, mentioning these type vars.
159 -- Acts as a template for the expansion when
160 -- the tycon is applied to some types.
164 type FieldLabel = Name
166 type ArgVrcs = [(Bool,Bool)] -- Tyvar variance info: [(occPos,occNeg)]
167 -- [] means "no information, assume the worst"
170 = AbstractTyCon -- We know nothing about this data type, except
171 -- that it's represented by a pointer
172 -- Used when we export a data type abstractly into
176 [DataCon] -- The constructors; can be empty if the user declares
177 -- the type to have no constructors
178 -- INVARIANT: Kept in order of increasing tag
179 -- (see the tag assignment in DataCon.mkDataCon)
180 Bool -- Cached: True <=> an enumeration type
182 | NewTyCon -- Newtypes always have exactly one constructor
183 DataCon -- The unique constructor; it has no existentials
184 Type -- Cached: the argument type of the constructor
185 -- = the representation type of the tycon
187 Type -- Cached: the *ultimate* representation type
188 -- By 'ultimate' I mean that the rep type is not itself
189 -- a newtype or type synonym.
190 -- The rep type isn't entirely simple:
191 -- for a recursive newtype we pick () as the rep type
194 -- The rep type has free type variables the tyConTyVars
196 -- newtype T a = MkT [(a,Int)]
197 -- The rep type is [(a,Int)]
198 -- NB: the rep type isn't necessarily the original RHS of the
199 -- newtype decl, because the rep type looks through other
202 visibleDataCons :: AlgTyConRhs -> [DataCon]
203 visibleDataCons AbstractTyCon = []
204 visibleDataCons (DataTyCon cs _) = cs
205 visibleDataCons (NewTyCon c _ _) = [c]
208 %************************************************************************
212 %************************************************************************
214 A PrimRep is an abstraction of a type. It contains information that
215 the code generator needs in order to pass arguments, return results,
216 and store values of this type.
218 A PrimRep is somewhat similar to a CgRep (see codeGen/SMRep) and a
219 MachRep (see cmm/MachOp), although each of these types has a distinct
220 and clearly defined purpose:
222 - A PrimRep is a CgRep + information about signedness + information
223 about primitive pointers (AddrRep). Signedness and primitive
224 pointers are required when passing a primitive type to a foreign
225 function, but aren't needed for call/return conventions of Haskell
228 - A MachRep is a basic machine type (non-void, doesn't contain
229 information on pointerhood or signedness, but contains some
230 reps that don't have corresponding Haskell types).
236 | IntRep -- signed, word-sized
237 | WordRep -- unsinged, word-sized
238 | Int64Rep -- signed, 64 bit (32-bit words only)
239 | Word64Rep -- unsigned, 64 bit (32-bit words only)
240 | AddrRep -- a pointer, but not to a Haskell value
245 %************************************************************************
247 \subsection{TyCon Construction}
249 %************************************************************************
251 Note: the TyCon constructors all take a Kind as one argument, even though
252 they could, in principle, work out their Kind from their other arguments.
253 But to do so they need functions from Types, and that makes a nasty
254 module mutual-recursion. And they aren't called from many places.
255 So we compromise, and move their Kind calculation to the call site.
258 mkFunTyCon :: Name -> Kind -> TyCon
261 tyConUnique = nameUnique name,
267 -- This is the making of a TyCon. Just the same as the old mkAlgTyCon,
268 -- but now you also have to pass in the generic information about the type
269 -- constructor - you can get hold of it easily (see Generics module)
270 mkAlgTyCon name kind tyvars argvrcs stupid rhs flds is_rec gen_info
273 tyConUnique = nameUnique name,
275 tyConArity = length tyvars,
276 tyConTyVars = tyvars,
278 algTcStupidTheta = stupid,
281 algTcClass = Nothing,
283 hasGenerics = gen_info
286 mkClassTyCon name kind tyvars argvrcs rhs clas is_rec
289 tyConUnique = nameUnique name,
291 tyConArity = length tyvars,
292 tyConTyVars = tyvars,
294 algTcStupidTheta = [],
297 algTcClass = Just clas,
303 mkTupleTyCon name kind arity tyvars con boxed gen_info
305 tyConUnique = nameUnique name,
310 tyConTyVars = tyvars,
312 hasGenerics = gen_info
315 -- Foreign-imported (.NET) type constructors are represented
316 -- as primitive, but *lifted*, TyCons for now. They are lifted
317 -- because the Haskell type T representing the (foreign) .NET
318 -- type T is actually implemented (in ILX) as a thunk<T>
319 mkForeignTyCon name ext_name kind arity arg_vrcs
322 tyConUnique = nameUnique name,
326 primTyConRep = PtrRep, -- they all do
328 tyConExtName = ext_name
332 -- most Prim tycons are lifted
333 mkPrimTyCon name kind arity arg_vrcs rep
334 = mkPrimTyCon' name kind arity arg_vrcs rep True
336 -- but RealWorld is lifted
337 mkLiftedPrimTyCon name kind arity arg_vrcs rep
338 = mkPrimTyCon' name kind arity arg_vrcs rep False
340 mkPrimTyCon' name kind arity arg_vrcs rep is_unlifted
343 tyConUnique = nameUnique name,
348 isUnLifted = is_unlifted,
349 tyConExtName = Nothing
352 mkSynTyCon name kind tyvars rhs argvrcs
355 tyConUnique = nameUnique name,
357 tyConArity = length tyvars,
358 tyConTyVars = tyvars,
365 isFunTyCon :: TyCon -> Bool
366 isFunTyCon (FunTyCon {}) = True
369 isAbstractTyCon :: TyCon -> Bool
370 isAbstractTyCon (AlgTyCon { algTcRhs = AbstractTyCon }) = True
371 isAbstractTyCon _ = False
373 makeTyConAbstract :: TyCon -> TyCon
374 makeTyConAbstract tc@(AlgTyCon {}) = tc { algTcRhs = AbstractTyCon }
375 makeTyConAbstract tc = pprPanic "makeTyConAbstract" (ppr tc)
377 isPrimTyCon :: TyCon -> Bool
378 isPrimTyCon (PrimTyCon {}) = True
379 isPrimTyCon _ = False
381 isUnLiftedTyCon :: TyCon -> Bool
382 isUnLiftedTyCon (PrimTyCon {isUnLifted = is_unlifted}) = is_unlifted
383 isUnLiftedTyCon (TupleTyCon {tyConBoxed = boxity}) = not (isBoxed boxity)
384 isUnLiftedTyCon _ = False
386 -- isAlgTyCon returns True for both @data@ and @newtype@
387 isAlgTyCon :: TyCon -> Bool
388 isAlgTyCon (AlgTyCon {}) = True
389 isAlgTyCon (TupleTyCon {}) = True
390 isAlgTyCon other = False
392 isDataTyCon :: TyCon -> Bool
393 -- isDataTyCon returns True for data types that are represented by
394 -- heap-allocated constructors.
395 -- These are srcutinised by Core-level @case@ expressions, and they
396 -- get info tables allocated for them.
397 -- True for all @data@ types
398 -- False for newtypes
400 isDataTyCon tc@(AlgTyCon {algTcRhs = rhs})
402 DataTyCon _ _ -> True
403 NewTyCon _ _ _ -> False
404 AbstractTyCon -> pprPanic "isDataTyCon" (ppr tc)
406 isDataTyCon (TupleTyCon {tyConBoxed = boxity}) = isBoxed boxity
407 isDataTyCon other = False
409 isNewTyCon :: TyCon -> Bool
410 isNewTyCon (AlgTyCon {algTcRhs = NewTyCon _ _ _}) = True
411 isNewTyCon other = False
413 isProductTyCon :: TyCon -> Bool
415 -- has *one* constructor,
416 -- is *not* existential
418 -- may be DataType or NewType,
419 -- may be unboxed or not,
420 -- may be recursive or not
421 isProductTyCon tc@(AlgTyCon {}) = case algTcRhs tc of
422 DataTyCon [data_con] _ -> isVanillaDataCon data_con
423 NewTyCon _ _ _ -> True
425 isProductTyCon (TupleTyCon {}) = True
426 isProductTyCon other = False
428 isSynTyCon :: TyCon -> Bool
429 isSynTyCon (SynTyCon {}) = True
432 isEnumerationTyCon :: TyCon -> Bool
433 isEnumerationTyCon (AlgTyCon {algTcRhs = DataTyCon _ is_enum}) = is_enum
434 isEnumerationTyCon other = False
436 isTupleTyCon :: TyCon -> Bool
437 -- The unit tycon didn't used to be classed as a tuple tycon
438 -- but I thought that was silly so I've undone it
439 -- If it can't be for some reason, it should be a AlgTyCon
441 -- NB: when compiling Data.Tuple, the tycons won't reply True to
442 -- isTupleTyCon, becuase they are built as AlgTyCons. However they
443 -- get spat into the interface file as tuple tycons, so I don't think
445 isTupleTyCon (TupleTyCon {}) = True
446 isTupleTyCon other = False
448 isUnboxedTupleTyCon :: TyCon -> Bool
449 isUnboxedTupleTyCon (TupleTyCon {tyConBoxed = boxity}) = not (isBoxed boxity)
450 isUnboxedTupleTyCon other = False
452 isBoxedTupleTyCon :: TyCon -> Bool
453 isBoxedTupleTyCon (TupleTyCon {tyConBoxed = boxity}) = isBoxed boxity
454 isBoxedTupleTyCon other = False
456 tupleTyConBoxity tc = tyConBoxed tc
458 isRecursiveTyCon :: TyCon -> Bool
459 isRecursiveTyCon (AlgTyCon {algTcRec = Recursive}) = True
460 isRecursiveTyCon other = False
462 isHiBootTyCon :: TyCon -> Bool
463 -- Used for knot-tying in hi-boot files
464 isHiBootTyCon (AlgTyCon {algTcRhs = AbstractTyCon}) = True
465 isHiBootTyCon other = False
467 isForeignTyCon :: TyCon -> Bool
468 -- isForeignTyCon identifies foreign-imported type constructors
469 isForeignTyCon (PrimTyCon {tyConExtName = Just _}) = True
470 isForeignTyCon other = False
474 tyConHasGenerics :: TyCon -> Bool
475 tyConHasGenerics (AlgTyCon {hasGenerics = hg}) = hg
476 tyConHasGenerics (TupleTyCon {hasGenerics = hg}) = hg
477 tyConHasGenerics other = False -- Synonyms
479 tyConDataCons :: TyCon -> [DataCon]
480 -- It's convenient for tyConDataCons to return the
481 -- empty list for type synonyms etc
482 tyConDataCons tycon = tyConDataCons_maybe tycon `orElse` []
484 tyConDataCons_maybe :: TyCon -> Maybe [DataCon]
485 tyConDataCons_maybe (AlgTyCon {algTcRhs = DataTyCon cons _}) = Just cons
486 tyConDataCons_maybe (AlgTyCon {algTcRhs = NewTyCon con _ _}) = Just [con]
487 tyConDataCons_maybe (TupleTyCon {dataCon = con}) = Just [con]
488 tyConDataCons_maybe other = Nothing
490 tyConFamilySize :: TyCon -> Int
491 tyConFamilySize (AlgTyCon {algTcRhs = DataTyCon cons _}) = length cons
492 tyConFamilySize (AlgTyCon {algTcRhs = NewTyCon _ _ _}) = 1
493 tyConFamilySize (TupleTyCon {}) = 1
495 tyConFamilySize other = pprPanic "tyConFamilySize:" (ppr other)
498 tyConFields :: TyCon -> [(FieldLabel,Type,Id)]
499 tyConFields (AlgTyCon {algTcFields = fs}) = fs
500 tyConFields other_tycon = []
502 tyConSelIds :: TyCon -> [Id]
503 tyConSelIds tc = [id | (_,_,id) <- tyConFields tc]
505 algTyConRhs :: TyCon -> AlgTyConRhs
506 algTyConRhs (AlgTyCon {algTcRhs = rhs}) = rhs
507 algTyConRhs (TupleTyCon {dataCon = con}) = DataTyCon [con] False
508 algTyConRhs other = pprPanic "algTyConRhs" (ppr other)
512 newTyConRhs :: TyCon -> ([TyVar], Type)
513 newTyConRhs (AlgTyCon {tyConTyVars = tvs, algTcRhs = NewTyCon _ rhs _}) = (tvs, rhs)
514 newTyConRhs tycon = pprPanic "newTyConRhs" (ppr tycon)
516 newTyConRhs_maybe :: TyCon
517 -> [Type] -- Args to tycon
518 -> Maybe ([(TyVar,Type)], -- Substitution
519 Type) -- Body type (not yet substituted)
520 -- Non-recursive newtypes are transparent to Core;
521 -- Given an application to some types, return Just (tenv, ty)
522 -- if it's a saturated, non-recursive newtype.
523 newTyConRhs_maybe (AlgTyCon {tyConTyVars = tvs,
524 algTcRec = NonRecursive, -- Not recursive
525 algTcRhs = NewTyCon _ rhs _}) tys
526 | tvs `equalLength` tys -- Saturated
527 = Just (tvs `zip` tys, rhs)
529 newTyConRhs_maybe other_tycon tys = Nothing
532 newTyConRep :: TyCon -> ([TyVar], Type)
533 newTyConRep (AlgTyCon {tyConTyVars = tvs, algTcRhs = NewTyCon _ _ rep}) = (tvs, rep)
534 newTyConRep tycon = pprPanic "newTyConRep" (ppr tycon)
536 tyConPrimRep :: TyCon -> PrimRep
537 tyConPrimRep (PrimTyCon {primTyConRep = rep}) = rep
538 tyConPrimRep tc = ASSERT(not (isUnboxedTupleTyCon tc)) PtrRep
542 tyConStupidTheta :: TyCon -> [PredType]
543 tyConStupidTheta (AlgTyCon {algTcStupidTheta = stupid}) = stupid
544 tyConStupidTheta (TupleTyCon {}) = []
545 tyConStupidTheta tycon = pprPanic "tyConStupidTheta" (ppr tycon)
548 @tyConArgVrcs_maybe@ gives a list of (occPos,occNeg) flags, one for
549 each tyvar, if available. See @calcAlgTyConArgVrcs@ for how this is
550 actually computed (in another file).
553 tyConArgVrcs :: TyCon -> ArgVrcs
554 tyConArgVrcs (FunTyCon {}) = [(False,True),(True,False)]
555 tyConArgVrcs (AlgTyCon {argVrcs = oi}) = oi
556 tyConArgVrcs (PrimTyCon {argVrcs = oi}) = oi
557 tyConArgVrcs (TupleTyCon {tyConArity = arity}) = (replicate arity (True,False))
558 tyConArgVrcs (SynTyCon {argVrcs = oi}) = oi
562 getSynTyConDefn :: TyCon -> ([TyVar], Type)
563 getSynTyConDefn (SynTyCon {tyConTyVars = tyvars, synTyConDefn = ty}) = (tyvars,ty)
564 getSynTyConDefn tycon = pprPanic "getSynTyConDefn" (ppr tycon)
568 maybeTyConSingleCon :: TyCon -> Maybe DataCon
569 maybeTyConSingleCon (AlgTyCon {algTcRhs = DataTyCon [c] _}) = Just c
570 maybeTyConSingleCon (AlgTyCon {algTcRhs = NewTyCon c _ _}) = Just c
571 maybeTyConSingleCon (AlgTyCon {}) = Nothing
572 maybeTyConSingleCon (TupleTyCon {dataCon = con}) = Just con
573 maybeTyConSingleCon (PrimTyCon {}) = Nothing
574 maybeTyConSingleCon (FunTyCon {}) = Nothing -- case at funty
575 maybeTyConSingleCon tc = pprPanic "maybeTyConSingleCon: unexpected tycon " $ ppr tc
579 isClassTyCon :: TyCon -> Bool
580 isClassTyCon (AlgTyCon {algTcClass = Just _}) = True
581 isClassTyCon other_tycon = False
583 tyConClass_maybe :: TyCon -> Maybe Class
584 tyConClass_maybe (AlgTyCon {algTcClass = maybe_clas}) = maybe_clas
585 tyConClass_maybe ther_tycon = Nothing
589 %************************************************************************
591 \subsection[TyCon-instances]{Instance declarations for @TyCon@}
593 %************************************************************************
595 @TyCon@s are compared by comparing their @Unique@s.
597 The strictness analyser needs @Ord@. It is a lexicographic order with
598 the property @(a<=b) || (b<=a)@.
601 instance Eq TyCon where
602 a == b = case (a `compare` b) of { EQ -> True; _ -> False }
603 a /= b = case (a `compare` b) of { EQ -> False; _ -> True }
605 instance Ord TyCon where
606 a <= b = case (a `compare` b) of { LT -> True; EQ -> True; GT -> False }
607 a < b = case (a `compare` b) of { LT -> True; EQ -> False; GT -> False }
608 a >= b = case (a `compare` b) of { LT -> False; EQ -> True; GT -> True }
609 a > b = case (a `compare` b) of { LT -> False; EQ -> False; GT -> True }
610 compare a b = getUnique a `compare` getUnique b
612 instance Uniquable TyCon where
613 getUnique tc = tyConUnique tc
615 instance Outputable TyCon where
616 ppr tc = ppr (getName tc)
618 instance NamedThing TyCon where