2 % (c) The University of Glasgow 2006
3 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
16 AlgTyConRhs(..), visibleDataCons,
20 isFunTyCon, isUnLiftedTyCon, isProductTyCon,
21 isAlgTyCon, isDataTyCon,
22 isNewTyCon, unwrapNewTyCon_maybe,
23 isSynTyCon, isClosedSynTyCon, isOpenSynTyCon,
26 isEnumerationTyCon, isGadtSyntaxTyCon, isOpenTyCon,
27 assocTyConArgPoss_maybe, isTyConAssoc, setTyConArgPoss,
28 isTupleTyCon, isUnboxedTupleTyCon, isBoxedTupleTyCon, tupleTyConBoxity,
29 isRecursiveTyCon, newTyConRhs, newTyConEtadRhs, newTyConCo_maybe,
30 isHiBootTyCon, isSuperKindTyCon,
31 isCoercionTyCon_maybe, isCoercionTyCon,
34 tcExpandTyCon_maybe, coreExpandTyCon_maybe,
36 makeTyConAbstract, isAbstractTyCon,
38 mkForeignTyCon, isForeignTyCon,
55 algTyConRhs, tyConDataCons, tyConDataCons_maybe, tyConFamilySize,
59 isClassTyCon, tyConClass_maybe,
60 isFamInstTyCon, tyConFamInst_maybe, tyConFamilyCoercion_maybe,
61 synTyConDefn, synTyConRhs, synTyConType, synTyConResKind,
62 tyConExtName, -- External name for foreign types
70 #include "HsVersions.h"
72 import {-# SOURCE #-} TypeRep ( Kind, Type, PredType )
73 import {-# SOURCE #-} DataCon ( DataCon, isVanillaDataCon )
86 %************************************************************************
88 \subsection{The data type}
90 %************************************************************************
95 tyConUnique :: Unique,
102 | AlgTyCon { -- Data type, and newtype decls.
103 -- All lifted, all boxed
104 tyConUnique :: Unique,
109 tyConTyVars :: [TyVar], -- Scopes over (a) the algTcStupidTheta
110 -- (b) the cached types in
111 -- algTyConRhs.NewTyCon
112 -- (c) the family instance
114 -- But not over the data constructors
116 algTcSelIds :: [Id], -- Its record selectors (empty if none)
118 algTcGadtSyntax :: Bool, -- True <=> the data type was declared using GADT syntax
119 -- That doesn't mean it's a true GADT; only that the "where"
120 -- form was used. This field is used only to guide
122 algTcStupidTheta :: [PredType], -- The "stupid theta" for the data type
123 -- (always empty for GADTs)
125 algTcRhs :: AlgTyConRhs, -- Data constructors in here
127 algTcRec :: RecFlag, -- Tells whether the data type is part
128 -- of a mutually-recursive group or not
130 hasGenerics :: Bool, -- True <=> generic to/from functions are available
131 -- (in the exports of the data type's source module)
133 algTcParent :: TyConParent -- Gives the class or family tycon for
134 -- derived tycons representing classes
135 -- or family instances, respectively.
139 tyConUnique :: Unique,
143 tyConBoxed :: Boxity,
144 tyConTyVars :: [TyVar],
150 tyConUnique :: Unique,
155 tyConTyVars :: [TyVar], -- Bound tyvars
157 synTcRhs :: SynTyConRhs, -- Expanded type in here
159 synTcParent :: TyConParent -- Gives the family tycon of
160 -- representation tycons of family
165 | PrimTyCon { -- Primitive types; cannot be defined in Haskell
166 -- Now includes foreign-imported types
167 -- Also includes Kinds
168 tyConUnique :: Unique,
171 tyConArity :: Arity, -- SLPJ Oct06: I'm not sure what the significance
172 -- of the arity of a primtycon is!
174 primTyConRep :: PrimRep,
175 -- Many primitive tycons are unboxed, but some are
176 -- boxed (represented by pointers). The CgRep tells.
178 isUnLifted :: Bool, -- Most primitive tycons are unlifted,
179 -- but foreign-imported ones may not be
180 tyConExtName :: Maybe FastString -- Just xx for foreign-imported types
183 | CoercionTyCon { -- E.g. (:=:), sym, trans, left, right
184 -- INVARIANT: coercions are always fully applied
185 tyConUnique :: Unique,
188 coKindFun :: [Type] -> (Type,Type)
189 } -- INVARIANT: coKindFun is always applied to exactly 'arity' args
190 -- E.g. for trans (c1 :: ta=tb) (c2 :: tb=tc), the coKindFun returns
191 -- the kind as a pair of types: (ta,tc)
193 | SuperKindTyCon { -- Super Kinds, TY (box) and CO (diamond).
194 -- They have no kind; and arity zero
195 tyConUnique :: Unique,
199 type FieldLabel = Name
201 -- Right hand sides of type constructors for algebraic types
205 -- We know nothing about this data type, except that it's represented by a
206 -- pointer. Used when we export a data type abstractly into an hi file.
210 -- The constructor represents an open family without a fixed right hand
211 -- side. Additional instances can appear at any time.
213 -- These are introduced by either a top level decl:
215 -- or an assoicated data type decl, in a class decl:
221 otArgPoss :: Maybe [Int]
222 -- Nothing <=> top-level indexed type family
223 -- Just ns <=> associated (not toplevel) family
224 -- In the latter case, for each tyvar in the AT decl, 'ns' gives the
225 -- position of that tyvar in the class argument list (starting from 0).
226 -- NB: Length is less than tyConArity iff higher kind signature.
231 data_cons :: [DataCon],
232 -- The constructors; can be empty if the user declares
233 -- the type to have no constructors
234 -- INVARIANT: Kept in order of increasing tag
235 -- (see the tag assignment in DataCon.mkDataCon)
236 is_enum :: Bool -- Cached: True <=> an enumeration type
237 } -- Includes data types with no constructors.
240 data_con :: DataCon, -- The unique constructor; it has no existentials
242 nt_rhs :: Type, -- Cached: the argument type of the constructor
243 -- = the representation type of the tycon
244 -- The free tyvars of this type are the tyConTyVars
246 nt_co :: Maybe TyCon, -- A CoercionTyCon used to create the newtype
247 -- from the representation
248 -- Optional for non-recursive newtypes
249 -- See Note [Newtype coercions]
250 -- Invariant: arity = #tvs in nt_etad_rhs;
251 -- See Note [Newtype eta]
252 -- Watch out! If any newtypes become transparent
253 -- again check Trac #1072.
255 nt_etad_rhs :: ([TyVar], Type)
256 -- The same again, but this time eta-reduced
257 -- hence the [TyVar] which may be shorter than the declared
258 -- arity of the TyCon. See Note [Newtype eta]
261 visibleDataCons :: AlgTyConRhs -> [DataCon]
262 visibleDataCons AbstractTyCon = []
263 visibleDataCons OpenTyCon {} = []
264 visibleDataCons (DataTyCon{ data_cons = cs }) = cs
265 visibleDataCons (NewTyCon{ data_con = c }) = [c]
267 -- Both type classes as well as family instances imply implicit
268 -- type constructors. These implicit type constructors refer to their parent
269 -- structure (ie, the class or family from which they derive) using a type of
270 -- the following form. We use `TyConParent' for both algebraic and synonym
271 -- types, but the variant `ClassTyCon' will only be used by algebraic tycons.
274 = NoParentTyCon -- An ordinary type constructor has no parent.
276 | ClassTyCon -- Type constructors representing a class dictionary.
277 Class -- INVARIANT: the classTyCon of this Class is the current tycon
279 | FamilyTyCon -- Type constructors representing an instance of a type
280 TyCon -- The type family
281 [Type] -- Instance types; free variables are the tyConTyVars
282 -- of the current TyCon (not the family one)
283 -- INVARIANT: the number of types matches the arity
284 -- of the family tycon
285 TyCon -- A CoercionTyCon identifying the representation
286 -- type with the type instance family.
287 -- c.f. Note [Newtype coercions]
290 -- E.g. data intance T [a] = ...
291 -- gives a representation tycon:
293 -- axiom co a :: T [a] ~ :R7T a
294 -- with :R7T's algTcParent = FamilyTyCon T [a] co
296 okParent :: Name -> TyConParent -> Bool -- Checks invariants
297 okParent _ NoParentTyCon = True
298 okParent tc_name (ClassTyCon cls) = tyConName (classTyCon cls) == tc_name
299 okParent _ (FamilyTyCon fam_tc tys _co_tc) = tyConArity fam_tc == length tys
303 = OpenSynTyCon Kind -- Type family: *result* kind given
304 (Maybe [Int]) -- for associated families: for each tyvars in
305 -- the AT decl, gives the position of that
306 -- tyvar in the class argument list (starting
308 -- NB: Length is less than tyConArity
309 -- if higher kind signature.
311 | SynonymTyCon Type -- Mentioning head type vars. Acts as a template for
312 -- the expansion when the tycon is applied to some
316 Note [Newtype coercions]
317 ~~~~~~~~~~~~~~~~~~~~~~~~
318 The NewTyCon field nt_co is a a TyCon (a coercion constructor in fact)
319 which is used for coercing from the representation type of the
320 newtype, to the newtype itself. For example,
322 newtype T a = MkT (a -> a)
324 the NewTyCon for T will contain nt_co = CoT where CoT t : T t :=: t ->
325 t. This TyCon is a CoercionTyCon, so it does not have a kind on its
326 own; it basically has its own typing rule for the fully-applied
327 version. If the newtype T has k type variables then CoT has arity at
328 most k. In the case that the right hand side is a type application
329 ending with the same type variables as the left hand side, we
330 "eta-contract" the coercion. So if we had
332 newtype S a = MkT [a]
334 then we would generate the arity 0 coercion CoS : S :=: []. The
335 primary reason we do this is to make newtype deriving cleaner.
337 In the paper we'd write
338 axiom CoT : (forall t. T t) :=: (forall t. [t])
339 and then when we used CoT at a particular type, s, we'd say
341 which encodes as (TyConApp instCoercionTyCon [TyConApp CoT [], s])
343 But in GHC we instead make CoT into a new piece of type syntax, CoercionTyCon,
344 (like instCoercionTyCon, symCoercionTyCon etc), which must always
345 be saturated, but which encodes as
347 In the vocabulary of the paper it's as if we had axiom declarations
349 axiom CoT t : T t :=: [t]
354 newtype Parser m a = MkParser (Foogle m a)
355 Are these two types equal (to Core)?
358 Well, yes. But to see that easily we eta-reduce the RHS type of
359 Parser, in this case to ([], Froogle), so that even unsaturated applications
360 of Parser will work right. This eta reduction is done when the type
361 constructor is built, and cached in NewTyCon. The cached field is
362 only used in coreExpandTyCon_maybe.
364 Here's an example that I think showed up in practice
366 newtype T a = MkT [a]
367 newtype Foo m = MkFoo (forall a. m a -> Int)
373 w2 = MkFoo (\(MkT x) -> case w1 of MkFoo f -> f x)
375 After desugaring, and discarding the data constructors for the newtypes,
379 And now Lint complains unless Foo T == Foo [], and that requires T==[]
381 This point carries over to the newtype coercion, because we need to
383 w2 = w1 `cast` Foo CoT
385 so the coercion tycon CoT must have
390 Note [Indexed data types] (aka data type families)
391 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
392 See also Note [Wrappers for data instance tycons] in MkId.lhs
397 data instance T (b,c) where
398 T1 :: b -> c -> T (b,c)
401 * T is the "family TyCon"
403 * We make "representation TyCon" :R1T, thus:
405 T1 :: forall b c. b -> c -> :R1T b c
407 * It has a top-level coercion connecting it to the family TyCon
409 axiom :Co:R1T b c : T (b,c) ~ :R1T b c
411 * The data contructor T1 has a wrapper (which is what the source-level
414 $WT1 :: forall b c. b -> c -> T (b,c)
415 $WT1 b c (x::b) (y::c) = T1 b c x y `cast` sym (:Co:R1T b c)
417 * The representation TyCon :R1T has an AlgTyConParent of
419 FamilyTyCon T [(b,c)] :Co:R1T
423 %************************************************************************
427 %************************************************************************
429 A PrimRep is an abstraction of a type. It contains information that
430 the code generator needs in order to pass arguments, return results,
431 and store values of this type.
433 A PrimRep is somewhat similar to a CgRep (see codeGen/SMRep) and a
434 MachRep (see cmm/MachOp), although each of these types has a distinct
435 and clearly defined purpose:
437 - A PrimRep is a CgRep + information about signedness + information
438 about primitive pointers (AddrRep). Signedness and primitive
439 pointers are required when passing a primitive type to a foreign
440 function, but aren't needed for call/return conventions of Haskell
443 - A MachRep is a basic machine type (non-void, doesn't contain
444 information on pointerhood or signedness, but contains some
445 reps that don't have corresponding Haskell types).
451 | IntRep -- signed, word-sized
452 | WordRep -- unsinged, word-sized
453 | Int64Rep -- signed, 64 bit (32-bit words only)
454 | Word64Rep -- unsigned, 64 bit (32-bit words only)
455 | AddrRep -- a pointer, but not to a Haskell value
460 instance Outputable PrimRep where
461 ppr r = text (show r)
463 -- Size of a PrimRep, in words
464 primRepSizeW :: PrimRep -> Int
465 primRepSizeW IntRep = 1
466 primRepSizeW WordRep = 1
467 primRepSizeW Int64Rep = wORD64_SIZE `quot` wORD_SIZE
468 primRepSizeW Word64Rep= wORD64_SIZE `quot` wORD_SIZE
469 primRepSizeW FloatRep = 1 -- NB. might not take a full word
470 primRepSizeW DoubleRep= dOUBLE_SIZE `quot` wORD_SIZE
471 primRepSizeW AddrRep = 1
472 primRepSizeW PtrRep = 1
473 primRepSizeW VoidRep = 0
476 %************************************************************************
478 \subsection{TyCon Construction}
480 %************************************************************************
482 Note: the TyCon constructors all take a Kind as one argument, even though
483 they could, in principle, work out their Kind from their other arguments.
484 But to do so they need functions from Types, and that makes a nasty
485 module mutual-recursion. And they aren't called from many places.
486 So we compromise, and move their Kind calculation to the call site.
489 mkFunTyCon :: Name -> Kind -> TyCon
492 tyConUnique = nameUnique name,
498 -- This is the making of a TyCon. Just the same as the old mkAlgTyCon,
499 -- but now you also have to pass in the generic information about the type
500 -- constructor - you can get hold of it easily (see Generics module)
512 mkAlgTyCon name kind tyvars stupid rhs sel_ids parent is_rec gen_info gadt_syn
515 tyConUnique = nameUnique name,
517 tyConArity = length tyvars,
518 tyConTyVars = tyvars,
519 algTcStupidTheta = stupid,
521 algTcSelIds = sel_ids,
522 algTcParent = ASSERT( okParent name parent ) parent,
524 algTcGadtSyntax = gadt_syn,
525 hasGenerics = gen_info
528 mkClassTyCon :: Name -> Kind -> [TyVar] -> AlgTyConRhs -> Class -> RecFlag -> TyCon
529 mkClassTyCon name kind tyvars rhs clas is_rec =
530 mkAlgTyCon name kind tyvars [] rhs [] (ClassTyCon clas) is_rec False False
532 mkTupleTyCon :: Name -> Kind -> Arity -> [TyVar] -> DataCon -> Boxity -> Bool -> TyCon
533 mkTupleTyCon name kind arity tyvars con boxed gen_info
535 tyConUnique = nameUnique name,
540 tyConTyVars = tyvars,
542 hasGenerics = gen_info
545 -- Foreign-imported (.NET) type constructors are represented
546 -- as primitive, but *lifted*, TyCons for now. They are lifted
547 -- because the Haskell type T representing the (foreign) .NET
548 -- type T is actually implemented (in ILX) as a thunk<T>
549 mkForeignTyCon :: Name -> Maybe FastString -> Kind -> Arity -> TyCon
550 mkForeignTyCon name ext_name kind arity
553 tyConUnique = nameUnique name,
556 primTyConRep = PtrRep, -- they all do
558 tyConExtName = ext_name
562 -- most Prim tycons are lifted
563 mkPrimTyCon :: Name -> Kind -> Arity -> PrimRep -> TyCon
564 mkPrimTyCon name kind arity rep
565 = mkPrimTyCon' name kind arity rep True
567 mkVoidPrimTyCon :: Name -> Kind -> Arity -> TyCon
568 mkVoidPrimTyCon name kind arity
569 = mkPrimTyCon' name kind arity VoidRep True
571 -- but RealWorld is lifted
572 mkLiftedPrimTyCon :: Name -> Kind -> Arity -> PrimRep -> TyCon
573 mkLiftedPrimTyCon name kind arity rep
574 = mkPrimTyCon' name kind arity rep False
576 mkPrimTyCon' :: Name -> Kind -> Arity -> PrimRep -> Bool -> TyCon
577 mkPrimTyCon' name kind arity rep is_unlifted
580 tyConUnique = nameUnique name,
584 isUnLifted = is_unlifted,
585 tyConExtName = Nothing
588 mkSynTyCon :: Name -> Kind -> [TyVar] -> SynTyConRhs -> TyConParent -> TyCon
589 mkSynTyCon name kind tyvars rhs parent
592 tyConUnique = nameUnique name,
594 tyConArity = length tyvars,
595 tyConTyVars = tyvars,
600 mkCoercionTyCon :: Name -> Arity -> ([Type] -> (Type,Type)) -> TyCon
601 mkCoercionTyCon name arity kindRule
604 tyConUnique = nameUnique name,
609 -- Super kinds always have arity zero
610 mkSuperKindTyCon :: Name -> TyCon
611 mkSuperKindTyCon name
614 tyConUnique = nameUnique name
619 isFunTyCon :: TyCon -> Bool
620 isFunTyCon (FunTyCon {}) = True
623 isAbstractTyCon :: TyCon -> Bool
624 isAbstractTyCon (AlgTyCon { algTcRhs = AbstractTyCon }) = True
625 isAbstractTyCon _ = False
627 makeTyConAbstract :: TyCon -> TyCon
628 makeTyConAbstract tc@(AlgTyCon {}) = tc { algTcRhs = AbstractTyCon }
629 makeTyConAbstract tc = pprPanic "makeTyConAbstract" (ppr tc)
631 isPrimTyCon :: TyCon -> Bool
632 isPrimTyCon (PrimTyCon {}) = True
633 isPrimTyCon _ = False
635 isUnLiftedTyCon :: TyCon -> Bool
636 isUnLiftedTyCon (PrimTyCon {isUnLifted = is_unlifted}) = is_unlifted
637 isUnLiftedTyCon (TupleTyCon {tyConBoxed = boxity}) = not (isBoxed boxity)
638 isUnLiftedTyCon _ = False
640 -- isAlgTyCon returns True for both @data@ and @newtype@
641 isAlgTyCon :: TyCon -> Bool
642 isAlgTyCon (AlgTyCon {}) = True
643 isAlgTyCon (TupleTyCon {}) = True
646 isDataTyCon :: TyCon -> Bool
647 -- isDataTyCon returns True for data types that are definitely
648 -- represented by heap-allocated constructors.
649 -- These are srcutinised by Core-level @case@ expressions, and they
650 -- get info tables allocated for them.
651 -- True for all @data@ types
652 -- False for newtypes
656 -- NB: for a data type family, T, only the *instance* tycons are
657 -- get an info table etc. The family tycon does not.
658 -- Hence False for OpenTyCon
659 isDataTyCon (AlgTyCon {algTcRhs = rhs})
661 OpenTyCon {} -> False
664 AbstractTyCon -> False -- We don't know, so return False
665 isDataTyCon (TupleTyCon {tyConBoxed = boxity}) = isBoxed boxity
666 isDataTyCon _ = False
668 isNewTyCon :: TyCon -> Bool
669 isNewTyCon (AlgTyCon {algTcRhs = NewTyCon {}}) = True
672 unwrapNewTyCon_maybe :: TyCon -> Maybe ([TyVar], Type, Maybe TyCon)
673 unwrapNewTyCon_maybe (AlgTyCon { tyConTyVars = tvs,
674 algTcRhs = NewTyCon { nt_co = mb_co,
676 = Just (tvs, rhs, mb_co)
677 unwrapNewTyCon_maybe _ = Nothing
679 isProductTyCon :: TyCon -> Bool
681 -- has *one* constructor,
682 -- is *not* existential
684 -- may be DataType, NewType
685 -- may be unboxed or not,
686 -- may be recursive or not
688 isProductTyCon tc@(AlgTyCon {}) = case algTcRhs tc of
689 DataTyCon{ data_cons = [data_con] }
690 -> isVanillaDataCon data_con
693 isProductTyCon (TupleTyCon {}) = True
694 isProductTyCon _ = False
696 isSynTyCon :: TyCon -> Bool
697 isSynTyCon (SynTyCon {}) = True
700 -- As for newtypes, it is in some contexts important to distinguish between
701 -- closed synonyms and synonym families, as synonym families have no unique
702 -- right hand side to which a synonym family application can expand.
704 isClosedSynTyCon :: TyCon -> Bool
705 isClosedSynTyCon tycon = isSynTyCon tycon && not (isOpenTyCon tycon)
707 isOpenSynTyCon :: TyCon -> Bool
708 isOpenSynTyCon tycon = isSynTyCon tycon && isOpenTyCon tycon
710 isGadtSyntaxTyCon :: TyCon -> Bool
711 isGadtSyntaxTyCon (AlgTyCon { algTcGadtSyntax = res }) = res
712 isGadtSyntaxTyCon _ = False
714 isEnumerationTyCon :: TyCon -> Bool
715 isEnumerationTyCon (AlgTyCon {algTcRhs = DataTyCon { is_enum = res }}) = res
716 isEnumerationTyCon _ = False
718 isOpenTyCon :: TyCon -> Bool
719 isOpenTyCon (SynTyCon {synTcRhs = OpenSynTyCon _ _}) = True
720 isOpenTyCon (AlgTyCon {algTcRhs = OpenTyCon {} }) = True
721 isOpenTyCon _ = False
723 assocTyConArgPoss_maybe :: TyCon -> Maybe [Int]
724 assocTyConArgPoss_maybe (AlgTyCon {
725 algTcRhs = OpenTyCon {otArgPoss = poss}}) = poss
726 assocTyConArgPoss_maybe (SynTyCon { synTcRhs = OpenSynTyCon _ poss }) = poss
727 assocTyConArgPoss_maybe _ = Nothing
729 isTyConAssoc :: TyCon -> Bool
730 isTyConAssoc = isJust . assocTyConArgPoss_maybe
732 setTyConArgPoss :: TyCon -> [Int] -> TyCon
733 setTyConArgPoss tc@(AlgTyCon { algTcRhs = rhs }) poss =
734 tc { algTcRhs = rhs {otArgPoss = Just poss} }
735 setTyConArgPoss tc@(SynTyCon { synTcRhs = OpenSynTyCon ki _ }) poss =
736 tc { synTcRhs = OpenSynTyCon ki (Just poss) }
737 setTyConArgPoss tc _ = pprPanic "setTyConArgPoss" (ppr tc)
739 isTupleTyCon :: TyCon -> Bool
740 -- The unit tycon didn't used to be classed as a tuple tycon
741 -- but I thought that was silly so I've undone it
742 -- If it can't be for some reason, it should be a AlgTyCon
744 -- NB: when compiling Data.Tuple, the tycons won't reply True to
745 -- isTupleTyCon, becuase they are built as AlgTyCons. However they
746 -- get spat into the interface file as tuple tycons, so I don't think
748 isTupleTyCon (TupleTyCon {}) = True
749 isTupleTyCon _ = False
751 isUnboxedTupleTyCon :: TyCon -> Bool
752 isUnboxedTupleTyCon (TupleTyCon {tyConBoxed = boxity}) = not (isBoxed boxity)
753 isUnboxedTupleTyCon _ = False
755 isBoxedTupleTyCon :: TyCon -> Bool
756 isBoxedTupleTyCon (TupleTyCon {tyConBoxed = boxity}) = isBoxed boxity
757 isBoxedTupleTyCon _ = False
759 tupleTyConBoxity :: TyCon -> Boxity
760 tupleTyConBoxity tc = tyConBoxed tc
762 isRecursiveTyCon :: TyCon -> Bool
763 isRecursiveTyCon (AlgTyCon {algTcRec = Recursive}) = True
764 isRecursiveTyCon _ = False
766 isHiBootTyCon :: TyCon -> Bool
767 -- Used for knot-tying in hi-boot files
768 isHiBootTyCon (AlgTyCon {algTcRhs = AbstractTyCon}) = True
769 isHiBootTyCon _ = False
771 isForeignTyCon :: TyCon -> Bool
772 -- isForeignTyCon identifies foreign-imported type constructors
773 isForeignTyCon (PrimTyCon {tyConExtName = Just _}) = True
774 isForeignTyCon _ = False
776 isSuperKindTyCon :: TyCon -> Bool
777 isSuperKindTyCon (SuperKindTyCon {}) = True
778 isSuperKindTyCon _ = False
780 isCoercionTyCon_maybe :: TyCon -> Maybe (Arity, [Type] -> (Type,Type))
781 isCoercionTyCon_maybe (CoercionTyCon {tyConArity = ar, coKindFun = rule})
783 isCoercionTyCon_maybe _ = Nothing
785 isCoercionTyCon :: TyCon -> Bool
786 isCoercionTyCon (CoercionTyCon {}) = True
787 isCoercionTyCon _ = False
789 -- Identifies implicit tycons that, in particular, do not go into interface
790 -- files (because they are implicitly reconstructed when the interface is
795 -- * associated families are implicit, as they are re-constructed from
796 -- the class declaration in which they reside, and
797 -- * family instances are *not* implicit as they represent the instance body
798 -- (similar to a dfun does that for a class instance).
800 isImplicitTyCon :: TyCon -> Bool
801 isImplicitTyCon tycon | isTyConAssoc tycon = True
802 | isSynTyCon tycon = False
803 | isAlgTyCon tycon = isClassTyCon tycon ||
805 isImplicitTyCon _other = True
806 -- catches: FunTyCon, PrimTyCon,
807 -- CoercionTyCon, SuperKindTyCon
811 -----------------------------------------------
812 -- Expand type-constructor applications
813 -----------------------------------------------
816 tcExpandTyCon_maybe, coreExpandTyCon_maybe
818 -> [Type] -- Args to tycon
819 -> Maybe ([(TyVar,Type)], -- Substitution
820 Type, -- Body type (not yet substituted)
821 [Type]) -- Leftover args
823 -- For the *typechecker* view, we expand (closed) synonyms only
824 tcExpandTyCon_maybe (SynTyCon {tyConTyVars = tvs,
825 synTcRhs = SynonymTyCon rhs }) tys
827 tcExpandTyCon_maybe _ _ = Nothing
830 -- For the *Core* view, we expand synonyms only as well
832 coreExpandTyCon_maybe (AlgTyCon {algTcRec = NonRecursive, -- Not recursive
833 algTcRhs = NewTyCon { nt_etad_rhs = etad_rhs, nt_co = Nothing }}) tys
834 = case etad_rhs of -- Don't do this in the pattern match, lest we accidentally
835 -- match the etad_rhs of a *recursive* newtype
836 (tvs,rhs) -> expand tvs rhs tys
838 coreExpandTyCon_maybe tycon tys = tcExpandTyCon_maybe tycon tys
842 expand :: [TyVar] -> Type -- Template
844 -> Maybe ([(TyVar,Type)], Type, [Type]) -- Expansion
846 = case n_tvs `compare` length tys of
847 LT -> Just (tvs `zip` tys, rhs, drop n_tvs tys)
848 EQ -> Just (tvs `zip` tys, rhs, [])
855 tyConHasGenerics :: TyCon -> Bool
856 tyConHasGenerics (AlgTyCon {hasGenerics = hg}) = hg
857 tyConHasGenerics (TupleTyCon {hasGenerics = hg}) = hg
858 tyConHasGenerics _ = False -- Synonyms
860 tyConDataCons :: TyCon -> [DataCon]
861 -- It's convenient for tyConDataCons to return the
862 -- empty list for type synonyms etc
863 tyConDataCons tycon = tyConDataCons_maybe tycon `orElse` []
865 tyConDataCons_maybe :: TyCon -> Maybe [DataCon]
866 tyConDataCons_maybe (AlgTyCon {algTcRhs = DataTyCon { data_cons = cons }}) = Just cons
867 tyConDataCons_maybe (AlgTyCon {algTcRhs = NewTyCon { data_con = con }}) = Just [con]
868 tyConDataCons_maybe (TupleTyCon {dataCon = con}) = Just [con]
869 tyConDataCons_maybe _ = Nothing
871 tyConFamilySize :: TyCon -> Int
872 tyConFamilySize (AlgTyCon {algTcRhs = DataTyCon {data_cons = cons}}) =
874 tyConFamilySize (AlgTyCon {algTcRhs = NewTyCon {}}) = 1
875 tyConFamilySize (AlgTyCon {algTcRhs = OpenTyCon {}}) = 0
876 tyConFamilySize (TupleTyCon {}) = 1
877 tyConFamilySize other = pprPanic "tyConFamilySize:" (ppr other)
879 tyConSelIds :: TyCon -> [Id]
880 tyConSelIds (AlgTyCon {algTcSelIds = fs}) = fs
883 algTyConRhs :: TyCon -> AlgTyConRhs
884 algTyConRhs (AlgTyCon {algTcRhs = rhs}) = rhs
885 algTyConRhs (TupleTyCon {dataCon = con}) = DataTyCon { data_cons = [con], is_enum = False }
886 algTyConRhs other = pprPanic "algTyConRhs" (ppr other)
890 newTyConRhs :: TyCon -> ([TyVar], Type)
891 newTyConRhs (AlgTyCon {tyConTyVars = tvs, algTcRhs = NewTyCon { nt_rhs = rhs }}) = (tvs, rhs)
892 newTyConRhs tycon = pprPanic "newTyConRhs" (ppr tycon)
894 newTyConEtadRhs :: TyCon -> ([TyVar], Type)
895 newTyConEtadRhs (AlgTyCon {algTcRhs = NewTyCon { nt_etad_rhs = tvs_rhs }}) = tvs_rhs
896 newTyConEtadRhs tycon = pprPanic "newTyConEtadRhs" (ppr tycon)
898 newTyConCo_maybe :: TyCon -> Maybe TyCon
899 newTyConCo_maybe (AlgTyCon {algTcRhs = NewTyCon { nt_co = co }}) = co
900 newTyConCo_maybe _ = Nothing
902 tyConPrimRep :: TyCon -> PrimRep
903 tyConPrimRep (PrimTyCon {primTyConRep = rep}) = rep
904 tyConPrimRep tc = ASSERT(not (isUnboxedTupleTyCon tc)) PtrRep
908 tyConStupidTheta :: TyCon -> [PredType]
909 tyConStupidTheta (AlgTyCon {algTcStupidTheta = stupid}) = stupid
910 tyConStupidTheta (TupleTyCon {}) = []
911 tyConStupidTheta tycon = pprPanic "tyConStupidTheta" (ppr tycon)
915 synTyConDefn :: TyCon -> ([TyVar], Type)
916 synTyConDefn (SynTyCon {tyConTyVars = tyvars, synTcRhs = SynonymTyCon ty})
918 synTyConDefn tycon = pprPanic "getSynTyConDefn" (ppr tycon)
920 synTyConRhs :: TyCon -> SynTyConRhs
921 synTyConRhs (SynTyCon {synTcRhs = rhs}) = rhs
922 synTyConRhs tc = pprPanic "synTyConRhs" (ppr tc)
924 synTyConType :: TyCon -> Type
925 synTyConType tc = case synTcRhs tc of
927 _ -> pprPanic "synTyConType" (ppr tc)
929 synTyConResKind :: TyCon -> Kind
930 synTyConResKind (SynTyCon {synTcRhs = OpenSynTyCon kind _}) = kind
931 synTyConResKind tycon = pprPanic "synTyConResKind" (ppr tycon)
935 maybeTyConSingleCon :: TyCon -> Maybe DataCon
936 maybeTyConSingleCon (AlgTyCon {algTcRhs = DataTyCon {data_cons = [c] }}) = Just c
937 maybeTyConSingleCon (AlgTyCon {algTcRhs = NewTyCon { data_con = c }}) = Just c
938 maybeTyConSingleCon (AlgTyCon {}) = Nothing
939 maybeTyConSingleCon (TupleTyCon {dataCon = con}) = Just con
940 maybeTyConSingleCon (PrimTyCon {}) = Nothing
941 maybeTyConSingleCon (FunTyCon {}) = Nothing -- case at funty
942 maybeTyConSingleCon tc = pprPanic "maybeTyConSingleCon: unexpected tycon " $ ppr tc
946 isClassTyCon :: TyCon -> Bool
947 isClassTyCon (AlgTyCon {algTcParent = ClassTyCon _}) = True
948 isClassTyCon _ = False
950 tyConClass_maybe :: TyCon -> Maybe Class
951 tyConClass_maybe (AlgTyCon {algTcParent = ClassTyCon clas}) = Just clas
952 tyConClass_maybe _ = Nothing
954 isFamInstTyCon :: TyCon -> Bool
955 isFamInstTyCon (AlgTyCon {algTcParent = FamilyTyCon _ _ _ }) = True
956 isFamInstTyCon (SynTyCon {synTcParent = FamilyTyCon _ _ _ }) = True
957 isFamInstTyCon _ = False
959 tyConFamInst_maybe :: TyCon -> Maybe (TyCon, [Type])
960 tyConFamInst_maybe (AlgTyCon {algTcParent = FamilyTyCon fam instTys _}) =
962 tyConFamInst_maybe (SynTyCon {synTcParent = FamilyTyCon fam instTys _}) =
964 tyConFamInst_maybe _ =
967 tyConFamilyCoercion_maybe :: TyCon -> Maybe TyCon
968 tyConFamilyCoercion_maybe (AlgTyCon {algTcParent = FamilyTyCon _ _ coe}) =
970 tyConFamilyCoercion_maybe (SynTyCon {synTcParent = FamilyTyCon _ _ coe}) =
972 tyConFamilyCoercion_maybe _ =
977 %************************************************************************
979 \subsection[TyCon-instances]{Instance declarations for @TyCon@}
981 %************************************************************************
983 @TyCon@s are compared by comparing their @Unique@s.
985 The strictness analyser needs @Ord@. It is a lexicographic order with
986 the property @(a<=b) || (b<=a)@.
989 instance Eq TyCon where
990 a == b = case (a `compare` b) of { EQ -> True; _ -> False }
991 a /= b = case (a `compare` b) of { EQ -> False; _ -> True }
993 instance Ord TyCon where
994 a <= b = case (a `compare` b) of { LT -> True; EQ -> True; GT -> False }
995 a < b = case (a `compare` b) of { LT -> True; EQ -> False; GT -> False }
996 a >= b = case (a `compare` b) of { LT -> False; EQ -> True; GT -> True }
997 a > b = case (a `compare` b) of { LT -> False; EQ -> False; GT -> True }
998 compare a b = getUnique a `compare` getUnique b
1000 instance Uniquable TyCon where
1001 getUnique tc = tyConUnique tc
1003 instance Outputable TyCon where
1004 ppr tc = ppr (getName tc)
1006 instance NamedThing TyCon where