2 % (c) The University of Glasgow 2006
3 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
10 -- The above warning supression flag is a temporary kludge.
11 -- While working on this module you are encouraged to remove it and fix
12 -- any warnings in the module. See
13 -- http://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#Warnings
23 AlgTyConRhs(..), visibleDataCons,
27 isFunTyCon, isUnLiftedTyCon, isProductTyCon,
28 isAlgTyCon, isDataTyCon,
29 isNewTyCon, unwrapNewTyCon_maybe,
30 isSynTyCon, isClosedSynTyCon, isOpenSynTyCon,
33 isEnumerationTyCon, isGadtSyntaxTyCon, isOpenTyCon,
34 assocTyConArgPoss_maybe, isTyConAssoc, setTyConArgPoss,
35 isTupleTyCon, isUnboxedTupleTyCon, isBoxedTupleTyCon, tupleTyConBoxity,
36 isRecursiveTyCon, newTyConRep, newTyConRhs, newTyConEtadRhs, newTyConCo_maybe,
37 isHiBootTyCon, isSuperKindTyCon,
38 isCoercionTyCon_maybe, isCoercionTyCon,
41 tcExpandTyCon_maybe, coreExpandTyCon_maybe,
43 makeTyConAbstract, isAbstractTyCon,
45 mkForeignTyCon, isForeignTyCon,
62 algTyConRhs, tyConDataCons, tyConDataCons_maybe, tyConFamilySize,
66 isClassTyCon, tyConClass_maybe,
67 isFamInstTyCon, tyConFamInst_maybe, tyConFamilyCoercion_maybe,
68 synTyConDefn, synTyConRhs, synTyConType, synTyConResKind,
69 tyConExtName, -- External name for foreign types
77 #include "HsVersions.h"
79 import {-# SOURCE #-} TypeRep ( Kind, Type, PredType )
80 import {-# SOURCE #-} DataCon ( DataCon, isVanillaDataCon )
93 %************************************************************************
95 \subsection{The data type}
97 %************************************************************************
102 tyConUnique :: Unique,
109 | AlgTyCon { -- Data type, and newtype decls.
110 -- All lifted, all boxed
111 tyConUnique :: Unique,
116 tyConTyVars :: [TyVar], -- Scopes over (a) the algTcStupidTheta
117 -- (b) the cached types in
118 -- algTyConRhs.NewTyCon
119 -- (c) the family instance
121 -- But not over the data constructors
123 algTcSelIds :: [Id], -- Its record selectors (empty if none)
125 algTcGadtSyntax :: Bool, -- True <=> the data type was declared using GADT syntax
126 -- That doesn't mean it's a true GADT; only that the "where"
127 -- form was used. This field is used only to guide
129 algTcStupidTheta :: [PredType], -- The "stupid theta" for the data type
130 -- (always empty for GADTs)
132 algTcRhs :: AlgTyConRhs, -- Data constructors in here
134 algTcRec :: RecFlag, -- Tells whether the data type is part
135 -- of a mutually-recursive group or not
137 hasGenerics :: Bool, -- True <=> generic to/from functions are available
138 -- (in the exports of the data type's source module)
140 algTcParent :: TyConParent -- Gives the class or family tycon for
141 -- derived tycons representing classes
142 -- or family instances, respectively.
146 tyConUnique :: Unique,
150 tyConBoxed :: Boxity,
151 tyConTyVars :: [TyVar],
157 tyConUnique :: Unique,
162 tyConTyVars :: [TyVar], -- Bound tyvars
164 synTcRhs :: SynTyConRhs, -- Expanded type in here
166 synTcParent :: TyConParent -- Gives the family tycon of
167 -- representation tycons of family
172 | PrimTyCon { -- Primitive types; cannot be defined in Haskell
173 -- Now includes foreign-imported types
174 -- Also includes Kinds
175 tyConUnique :: Unique,
178 tyConArity :: Arity, -- SLPJ Oct06: I'm not sure what the significance
179 -- of the arity of a primtycon is!
181 primTyConRep :: PrimRep,
182 -- Many primitive tycons are unboxed, but some are
183 -- boxed (represented by pointers). The CgRep tells.
185 isUnLifted :: Bool, -- Most primitive tycons are unlifted,
186 -- but foreign-imported ones may not be
187 tyConExtName :: Maybe FastString -- Just xx for foreign-imported types
190 | CoercionTyCon { -- E.g. (:=:), sym, trans, left, right
191 -- INVARIANT: coercions are always fully applied
192 tyConUnique :: Unique,
195 coKindFun :: [Type] -> (Type,Type)
196 } -- INVARAINT: coKindFun is always applied to exactly 'arity' args
197 -- E.g. for trans (c1 :: ta=tb) (c2 :: tb=tc), the coKindFun returns
198 -- the kind as a pair of types: (ta,tc)
200 | SuperKindTyCon { -- Super Kinds, TY (box) and CO (diamond).
201 -- They have no kind; and arity zero
202 tyConUnique :: Unique,
206 type FieldLabel = Name
208 -- Right hand sides of type constructors for algebraic types
212 -- We know nothing about this data type, except that it's represented by a
213 -- pointer. Used when we export a data type abstractly into an hi file.
217 -- The constructor represents an open family without a fixed right hand
218 -- side. Additional instances can appear at any time.
220 -- These are introduced by either a top level decl:
222 -- or an assoicated data type decl, in a class decl:
228 otArgPoss :: Maybe [Int]
229 -- Nothing <=> top-level indexed type family
230 -- Just ns <=> associated (not toplevel) family
231 -- In the latter case, for each tyvar in the AT decl, 'ns' gives the
232 -- position of that tyvar in the class argument list (starting from 0).
233 -- NB: Length is less than tyConArity iff higher kind signature.
238 data_cons :: [DataCon],
239 -- The constructors; can be empty if the user declares
240 -- the type to have no constructors
241 -- INVARIANT: Kept in order of increasing tag
242 -- (see the tag assignment in DataCon.mkDataCon)
243 is_enum :: Bool -- Cached: True <=> an enumeration type
244 } -- Includes data types with no constructors.
247 data_con :: DataCon, -- The unique constructor; it has no existentials
249 nt_rhs :: Type, -- Cached: the argument type of the constructor
250 -- = the representation type of the tycon
251 -- The free tyvars of this type are the tyConTyVars
253 nt_co :: Maybe TyCon, -- A CoercionTyCon used to create the newtype
254 -- from the representation
255 -- Optional for non-recursive newtypes
256 -- See Note [Newtype coercions]
257 -- Invariant: arity = #tvs in nt_etad_rhs;
258 -- See Note [Newtype eta]
260 nt_etad_rhs :: ([TyVar], Type) ,
261 -- The same again, but this time eta-reduced
262 -- hence the [TyVar] which may be shorter than the declared
263 -- arity of the TyCon. See Note [Newtype eta]
265 nt_rep :: Type -- Cached: the *ultimate* representation type
266 -- By 'ultimate' I mean that the top-level constructor
267 -- of the rep type is not itself a newtype or type synonym.
268 -- The rep type isn't entirely simple:
269 -- for a recursive newtype we pick () as the rep type
272 -- This one does not need to be eta reduced; hence its
273 -- free type variables are conveniently tyConTyVars
275 -- newtype T a = MkT [(a,Int)]
276 -- The rep type is [(a,Int)]
277 -- NB: the rep type isn't necessarily the original RHS of the
278 -- newtype decl, because the rep type looks through other
281 visibleDataCons :: AlgTyConRhs -> [DataCon]
282 visibleDataCons AbstractTyCon = []
283 visibleDataCons OpenTyCon {} = []
284 visibleDataCons (DataTyCon{ data_cons = cs }) = cs
285 visibleDataCons (NewTyCon{ data_con = c }) = [c]
287 -- Both type classes as well as family instances imply implicit
288 -- type constructors. These implicit type constructors refer to their parent
289 -- structure (ie, the class or family from which they derive) using a type of
290 -- the following form. We use `TyConParent' for both algebraic and synonym
291 -- types, but the variant `ClassTyCon' will only be used by algebraic tycons.
294 = NoParentTyCon -- An ordinary type constructor has no parent.
296 | ClassTyCon -- Type constructors representing a class dictionary.
297 Class -- INVARIANT: the classTyCon of this Class is the current tycon
299 | FamilyTyCon -- Type constructors representing an instance of a type
300 TyCon -- The type family
301 [Type] -- Instance types; free variables are the tyConTyVars
302 -- of the current TyCon (not the family one)
303 -- INVARIANT: the number of types matches the arity
304 -- of the family tycon
305 TyCon -- A CoercionTyCon identifying the representation
306 -- type with the type instance family.
307 -- c.f. Note [Newtype coercions]
310 -- E.g. data intance T [a] = ...
311 -- gives a representation tycon:
313 -- axiom co a :: T [a] ~ :R7T a
314 -- with :R7T's algTcParent = FamilyTyCon T [a] co
316 okParent :: Name -> TyConParent -> Bool -- Checks invariants
317 okParent tc_name NoParentTyCon = True
318 okParent tc_name (ClassTyCon cls) = tyConName (classTyCon cls) == tc_name
319 okParent tc_name (FamilyTyCon fam_tc tys co_tc) = tyConArity fam_tc == length tys
323 = OpenSynTyCon Kind -- Type family: *result* kind given
324 (Maybe [Int]) -- for associated families: for each tyvars in
325 -- the AT decl, gives the position of that
326 -- tyvar in the class argument list (starting
328 -- NB: Length is less than tyConArity
329 -- if higher kind signature.
331 | SynonymTyCon Type -- Mentioning head type vars. Acts as a template for
332 -- the expansion when the tycon is applied to some
336 Note [Newtype coercions]
337 ~~~~~~~~~~~~~~~~~~~~~~~~
338 The NewTyCon field nt_co is a a TyCon (a coercion constructor in fact)
339 which is used for coercing from the representation type of the
340 newtype, to the newtype itself. For example,
342 newtype T a = MkT (a -> a)
344 the NewTyCon for T will contain nt_co = CoT where CoT t : T t :=: t ->
345 t. This TyCon is a CoercionTyCon, so it does not have a kind on its
346 own; it basically has its own typing rule for the fully-applied
347 version. If the newtype T has k type variables then CoT has arity at
348 most k. In the case that the right hand side is a type application
349 ending with the same type variables as the left hand side, we
350 "eta-contract" the coercion. So if we had
352 newtype S a = MkT [a]
354 then we would generate the arity 0 coercion CoS : S :=: []. The
355 primary reason we do this is to make newtype deriving cleaner.
357 In the paper we'd write
358 axiom CoT : (forall t. T t) :=: (forall t. [t])
359 and then when we used CoT at a particular type, s, we'd say
361 which encodes as (TyConApp instCoercionTyCon [TyConApp CoT [], s])
363 But in GHC we instead make CoT into a new piece of type syntax, CoercionTyCon,
364 (like instCoercionTyCon, symCoercionTyCon etc), which must always
365 be saturated, but which encodes as
367 In the vocabulary of the paper it's as if we had axiom declarations
369 axiom CoT t : T t :=: [t]
374 newtype Parser m a = MkParser (Foogle m a)
375 Are these two types equal (to Core)?
378 Well, yes. But to see that easily we eta-reduce the RHS type of
379 Parser, in this case to ([], Froogle), so that even unsaturated applications
380 of Parser will work right. This eta reduction is done when the type
381 constructor is built, and cached in NewTyCon. The cached field is
382 only used in coreExpandTyCon_maybe.
384 Here's an example that I think showed up in practice
386 newtype T a = MkT [a]
387 newtype Foo m = MkFoo (forall a. m a -> Int)
393 w2 = MkFoo (\(MkT x) -> case w1 of MkFoo f -> f x)
395 After desugaring, and discading the data constructors for the newtypes,
399 And now Lint complains unless Foo T == Foo [], and that requires T==[]
401 This point carries over to the newtype coercion, because we need to
403 w2 = w1 `cast` Foo CoT
405 so the coercion tycon CoT must have
410 Note [Indexed data types] (aka data type families)
411 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
412 See also Note [Wrappers for data instance tycons] in MkId.lhs
417 data instance T (b,c) where
418 T1 :: b -> c -> T (b,c)
421 * T is the "family TyCon"
423 * We make "representation TyCon" :R1T, thus:
425 T1 :: forall b c. b -> c -> :R1T b c
427 * It has a top-level coercion connecting it to the family TyCon
429 axiom :Co:R1T b c : T (b,c) ~ :R1T b c
431 * The data contructor T1 has a wrapper (which is what the source-level
434 $WT1 :: forall b c. b -> c -> T (b,c)
435 $WT1 b c (x::b) (y::c) = T1 b c x y `cast` sym (:Co:R1T b c)
437 * The representation TyCon :R1T has an AlgTyConParent of
439 FamilyTyCon T [(b,c)] :Co:R1T
443 %************************************************************************
447 %************************************************************************
449 A PrimRep is an abstraction of a type. It contains information that
450 the code generator needs in order to pass arguments, return results,
451 and store values of this type.
453 A PrimRep is somewhat similar to a CgRep (see codeGen/SMRep) and a
454 MachRep (see cmm/MachOp), although each of these types has a distinct
455 and clearly defined purpose:
457 - A PrimRep is a CgRep + information about signedness + information
458 about primitive pointers (AddrRep). Signedness and primitive
459 pointers are required when passing a primitive type to a foreign
460 function, but aren't needed for call/return conventions of Haskell
463 - A MachRep is a basic machine type (non-void, doesn't contain
464 information on pointerhood or signedness, but contains some
465 reps that don't have corresponding Haskell types).
471 | IntRep -- signed, word-sized
472 | WordRep -- unsinged, word-sized
473 | Int64Rep -- signed, 64 bit (32-bit words only)
474 | Word64Rep -- unsigned, 64 bit (32-bit words only)
475 | AddrRep -- a pointer, but not to a Haskell value
480 -- Size of a PrimRep, in bytes
481 sizeofPrimRep :: PrimRep -> Int
482 sizeofPrimRep IntRep = wORD_SIZE
483 sizeofPrimRep WordRep = wORD_SIZE
484 sizeofPrimRep Int64Rep = wORD64_SIZE
485 sizeofPrimRep Word64Rep= wORD64_SIZE
486 sizeofPrimRep FloatRep = 4
487 sizeofPrimRep DoubleRep= 8
488 sizeofPrimRep AddrRep = wORD_SIZE
489 sizeofPrimRep PtrRep = wORD_SIZE
490 sizeofPrimRep VoidRep = 0
493 %************************************************************************
495 \subsection{TyCon Construction}
497 %************************************************************************
499 Note: the TyCon constructors all take a Kind as one argument, even though
500 they could, in principle, work out their Kind from their other arguments.
501 But to do so they need functions from Types, and that makes a nasty
502 module mutual-recursion. And they aren't called from many places.
503 So we compromise, and move their Kind calculation to the call site.
506 mkFunTyCon :: Name -> Kind -> TyCon
509 tyConUnique = nameUnique name,
515 -- This is the making of a TyCon. Just the same as the old mkAlgTyCon,
516 -- but now you also have to pass in the generic information about the type
517 -- constructor - you can get hold of it easily (see Generics module)
518 mkAlgTyCon name kind tyvars stupid rhs sel_ids parent is_rec gen_info gadt_syn
521 tyConUnique = nameUnique name,
523 tyConArity = length tyvars,
524 tyConTyVars = tyvars,
525 algTcStupidTheta = stupid,
527 algTcSelIds = sel_ids,
528 algTcParent = ASSERT( okParent name parent ) parent,
530 algTcGadtSyntax = gadt_syn,
531 hasGenerics = gen_info
534 mkClassTyCon name kind tyvars rhs clas is_rec =
535 mkAlgTyCon name kind tyvars [] rhs [] (ClassTyCon clas) is_rec False False
537 mkTupleTyCon name kind arity tyvars con boxed gen_info
539 tyConUnique = nameUnique name,
544 tyConTyVars = tyvars,
546 hasGenerics = gen_info
549 -- Foreign-imported (.NET) type constructors are represented
550 -- as primitive, but *lifted*, TyCons for now. They are lifted
551 -- because the Haskell type T representing the (foreign) .NET
552 -- type T is actually implemented (in ILX) as a thunk<T>
553 mkForeignTyCon name ext_name kind arity
556 tyConUnique = nameUnique name,
559 primTyConRep = PtrRep, -- they all do
561 tyConExtName = ext_name
565 -- most Prim tycons are lifted
566 mkPrimTyCon name kind arity rep
567 = mkPrimTyCon' name kind arity rep True
569 mkVoidPrimTyCon name kind arity
570 = mkPrimTyCon' name kind arity VoidRep True
572 -- but RealWorld is lifted
573 mkLiftedPrimTyCon name kind arity rep
574 = mkPrimTyCon' name kind arity rep False
576 mkPrimTyCon' name kind arity rep is_unlifted
579 tyConUnique = nameUnique name,
583 isUnLifted = is_unlifted,
584 tyConExtName = Nothing
587 mkSynTyCon name kind tyvars rhs parent
590 tyConUnique = nameUnique name,
592 tyConArity = length tyvars,
593 tyConTyVars = tyvars,
598 mkCoercionTyCon name arity kindRule
601 tyConUnique = nameUnique name,
606 -- Super kinds always have arity zero
607 mkSuperKindTyCon name
610 tyConUnique = nameUnique name
615 isFunTyCon :: TyCon -> Bool
616 isFunTyCon (FunTyCon {}) = True
619 isAbstractTyCon :: TyCon -> Bool
620 isAbstractTyCon (AlgTyCon { algTcRhs = AbstractTyCon }) = True
621 isAbstractTyCon _ = False
623 makeTyConAbstract :: TyCon -> TyCon
624 makeTyConAbstract tc@(AlgTyCon {}) = tc { algTcRhs = AbstractTyCon }
625 makeTyConAbstract tc = pprPanic "makeTyConAbstract" (ppr tc)
627 isPrimTyCon :: TyCon -> Bool
628 isPrimTyCon (PrimTyCon {}) = True
629 isPrimTyCon _ = False
631 isUnLiftedTyCon :: TyCon -> Bool
632 isUnLiftedTyCon (PrimTyCon {isUnLifted = is_unlifted}) = is_unlifted
633 isUnLiftedTyCon (TupleTyCon {tyConBoxed = boxity}) = not (isBoxed boxity)
634 isUnLiftedTyCon _ = False
636 -- isAlgTyCon returns True for both @data@ and @newtype@
637 isAlgTyCon :: TyCon -> Bool
638 isAlgTyCon (AlgTyCon {}) = True
639 isAlgTyCon (TupleTyCon {}) = True
640 isAlgTyCon other = False
642 isDataTyCon :: TyCon -> Bool
643 -- isDataTyCon returns True for data types that are definitely
644 -- represented by heap-allocated constructors.
645 -- These are srcutinised by Core-level @case@ expressions, and they
646 -- get info tables allocated for them.
647 -- True for all @data@ types
648 -- False for newtypes
652 -- NB: for a data type family, T, only the *instance* tycons are
653 -- get an info table etc. The family tycon does not.
654 -- Hence False for OpenTyCon
655 isDataTyCon tc@(AlgTyCon {algTcRhs = rhs})
657 OpenTyCon {} -> False
660 AbstractTyCon -> False -- We don't know, so return False
661 isDataTyCon (TupleTyCon {tyConBoxed = boxity}) = isBoxed boxity
662 isDataTyCon other = False
664 isNewTyCon :: TyCon -> Bool
665 isNewTyCon (AlgTyCon {algTcRhs = NewTyCon {}}) = True
666 isNewTyCon other = False
668 unwrapNewTyCon_maybe :: TyCon -> Maybe ([TyVar], Type, Maybe TyCon)
669 unwrapNewTyCon_maybe (AlgTyCon { tyConTyVars = tvs,
670 algTcRhs = NewTyCon { nt_co = mb_co,
672 = Just (tvs, rhs, mb_co)
673 unwrapNewTyCon_maybe other = Nothing
675 isProductTyCon :: TyCon -> Bool
677 -- has *one* constructor,
678 -- is *not* existential
680 -- may be DataType, NewType
681 -- may be unboxed or not,
682 -- may be recursive or not
684 isProductTyCon tc@(AlgTyCon {}) = case algTcRhs tc of
685 DataTyCon{ data_cons = [data_con] }
686 -> isVanillaDataCon data_con
689 isProductTyCon (TupleTyCon {}) = True
690 isProductTyCon other = False
692 isSynTyCon :: TyCon -> Bool
693 isSynTyCon (SynTyCon {}) = True
696 -- As for newtypes, it is in some contexts important to distinguish between
697 -- closed synonyms and synonym families, as synonym families have no unique
698 -- right hand side to which a synonym family application can expand.
700 isClosedSynTyCon :: TyCon -> Bool
701 isClosedSynTyCon tycon = isSynTyCon tycon && not (isOpenTyCon tycon)
703 isOpenSynTyCon :: TyCon -> Bool
704 isOpenSynTyCon tycon = isSynTyCon tycon && isOpenTyCon tycon
706 isGadtSyntaxTyCon :: TyCon -> Bool
707 isGadtSyntaxTyCon (AlgTyCon { algTcGadtSyntax = res }) = res
708 isGadtSyntaxTyCon other = False
710 isEnumerationTyCon :: TyCon -> Bool
711 isEnumerationTyCon (AlgTyCon {algTcRhs = DataTyCon { is_enum = res }}) = res
712 isEnumerationTyCon other = False
714 isOpenTyCon :: TyCon -> Bool
715 isOpenTyCon (SynTyCon {synTcRhs = OpenSynTyCon _ _}) = True
716 isOpenTyCon (AlgTyCon {algTcRhs = OpenTyCon {} }) = True
717 isOpenTyCon _ = False
719 assocTyConArgPoss_maybe :: TyCon -> Maybe [Int]
720 assocTyConArgPoss_maybe (AlgTyCon {
721 algTcRhs = OpenTyCon {otArgPoss = poss}}) = poss
722 assocTyConArgPoss_maybe (SynTyCon { synTcRhs = OpenSynTyCon _ poss }) = poss
723 assocTyConArgPoss_maybe _ = Nothing
725 isTyConAssoc :: TyCon -> Bool
726 isTyConAssoc = isJust . assocTyConArgPoss_maybe
728 setTyConArgPoss :: TyCon -> [Int] -> TyCon
729 setTyConArgPoss tc@(AlgTyCon { algTcRhs = rhs }) poss =
730 tc { algTcRhs = rhs {otArgPoss = Just poss} }
731 setTyConArgPoss tc@(SynTyCon { synTcRhs = OpenSynTyCon ki _ }) poss =
732 tc { synTcRhs = OpenSynTyCon ki (Just poss) }
733 setTyConArgPoss tc _ = pprPanic "setTyConArgPoss" (ppr tc)
735 isTupleTyCon :: TyCon -> Bool
736 -- The unit tycon didn't used to be classed as a tuple tycon
737 -- but I thought that was silly so I've undone it
738 -- If it can't be for some reason, it should be a AlgTyCon
740 -- NB: when compiling Data.Tuple, the tycons won't reply True to
741 -- isTupleTyCon, becuase they are built as AlgTyCons. However they
742 -- get spat into the interface file as tuple tycons, so I don't think
744 isTupleTyCon (TupleTyCon {}) = True
745 isTupleTyCon other = False
747 isUnboxedTupleTyCon :: TyCon -> Bool
748 isUnboxedTupleTyCon (TupleTyCon {tyConBoxed = boxity}) = not (isBoxed boxity)
749 isUnboxedTupleTyCon other = False
751 isBoxedTupleTyCon :: TyCon -> Bool
752 isBoxedTupleTyCon (TupleTyCon {tyConBoxed = boxity}) = isBoxed boxity
753 isBoxedTupleTyCon other = False
755 tupleTyConBoxity tc = tyConBoxed tc
757 isRecursiveTyCon :: TyCon -> Bool
758 isRecursiveTyCon (AlgTyCon {algTcRec = Recursive}) = True
759 isRecursiveTyCon other = False
761 isHiBootTyCon :: TyCon -> Bool
762 -- Used for knot-tying in hi-boot files
763 isHiBootTyCon (AlgTyCon {algTcRhs = AbstractTyCon}) = True
764 isHiBootTyCon other = False
766 isForeignTyCon :: TyCon -> Bool
767 -- isForeignTyCon identifies foreign-imported type constructors
768 isForeignTyCon (PrimTyCon {tyConExtName = Just _}) = True
769 isForeignTyCon other = False
771 isSuperKindTyCon :: TyCon -> Bool
772 isSuperKindTyCon (SuperKindTyCon {}) = True
773 isSuperKindTyCon other = False
775 isCoercionTyCon_maybe :: TyCon -> Maybe (Arity, [Type] -> (Type,Type))
776 isCoercionTyCon_maybe (CoercionTyCon {tyConArity = ar, coKindFun = rule})
778 isCoercionTyCon_maybe other = Nothing
780 isCoercionTyCon :: TyCon -> Bool
781 isCoercionTyCon (CoercionTyCon {}) = True
782 isCoercionTyCon other = False
784 -- Identifies implicit tycons that, in particular, do not go into interface
785 -- files (because they are implicitly reconstructed when the interface is
790 -- * associated families are implicit, as they are re-constructed from
791 -- the class declaration in which they reside, and
792 -- * family instances are *not* implicit as they represent the instance body
793 -- (similar to a dfun does that for a class instance).
795 isImplicitTyCon :: TyCon -> Bool
796 isImplicitTyCon tycon | isTyConAssoc tycon = True
797 | isSynTyCon tycon = False
798 | isAlgTyCon tycon = isClassTyCon tycon ||
800 isImplicitTyCon _other = True
801 -- catches: FunTyCon, PrimTyCon,
802 -- CoercionTyCon, SuperKindTyCon
806 -----------------------------------------------
807 -- Expand type-constructor applications
808 -----------------------------------------------
811 tcExpandTyCon_maybe, coreExpandTyCon_maybe
813 -> [Type] -- Args to tycon
814 -> Maybe ([(TyVar,Type)], -- Substitution
815 Type, -- Body type (not yet substituted)
816 [Type]) -- Leftover args
818 -- For the *typechecker* view, we expand (closed) synonyms only
819 tcExpandTyCon_maybe (SynTyCon {tyConTyVars = tvs,
820 synTcRhs = SynonymTyCon rhs }) tys
822 tcExpandTyCon_maybe other_tycon tys = Nothing
825 -- For the *Core* view, we expand synonyms only as well
827 coreExpandTyCon_maybe (AlgTyCon {algTcRec = NonRecursive, -- Not recursive
828 algTcRhs = NewTyCon { nt_etad_rhs = etad_rhs, nt_co = Nothing }}) tys
829 = case etad_rhs of -- Don't do this in the pattern match, lest we accidentally
830 -- match the etad_rhs of a *recursive* newtype
831 (tvs,rhs) -> expand tvs rhs tys
833 coreExpandTyCon_maybe tycon tys = tcExpandTyCon_maybe tycon tys
837 expand :: [TyVar] -> Type -- Template
839 -> Maybe ([(TyVar,Type)], Type, [Type]) -- Expansion
841 = case n_tvs `compare` length tys of
842 LT -> Just (tvs `zip` tys, rhs, drop n_tvs tys)
843 EQ -> Just (tvs `zip` tys, rhs, [])
850 tyConHasGenerics :: TyCon -> Bool
851 tyConHasGenerics (AlgTyCon {hasGenerics = hg}) = hg
852 tyConHasGenerics (TupleTyCon {hasGenerics = hg}) = hg
853 tyConHasGenerics other = False -- Synonyms
855 tyConDataCons :: TyCon -> [DataCon]
856 -- It's convenient for tyConDataCons to return the
857 -- empty list for type synonyms etc
858 tyConDataCons tycon = tyConDataCons_maybe tycon `orElse` []
860 tyConDataCons_maybe :: TyCon -> Maybe [DataCon]
861 tyConDataCons_maybe (AlgTyCon {algTcRhs = DataTyCon { data_cons = cons }}) = Just cons
862 tyConDataCons_maybe (AlgTyCon {algTcRhs = NewTyCon { data_con = con }}) = Just [con]
863 tyConDataCons_maybe (TupleTyCon {dataCon = con}) = Just [con]
864 tyConDataCons_maybe other = Nothing
866 tyConFamilySize :: TyCon -> Int
867 tyConFamilySize (AlgTyCon {algTcRhs = DataTyCon {data_cons = cons}}) =
869 tyConFamilySize (AlgTyCon {algTcRhs = NewTyCon {}}) = 1
870 tyConFamilySize (AlgTyCon {algTcRhs = OpenTyCon {}}) = 0
871 tyConFamilySize (TupleTyCon {}) = 1
873 tyConFamilySize other = pprPanic "tyConFamilySize:" (ppr other)
876 tyConSelIds :: TyCon -> [Id]
877 tyConSelIds (AlgTyCon {algTcSelIds = fs}) = fs
878 tyConSelIds other_tycon = []
880 algTyConRhs :: TyCon -> AlgTyConRhs
881 algTyConRhs (AlgTyCon {algTcRhs = rhs}) = rhs
882 algTyConRhs (TupleTyCon {dataCon = con}) = DataTyCon { data_cons = [con], is_enum = False }
883 algTyConRhs other = pprPanic "algTyConRhs" (ppr other)
887 newTyConRhs :: TyCon -> ([TyVar], Type)
888 newTyConRhs (AlgTyCon {tyConTyVars = tvs, algTcRhs = NewTyCon { nt_rhs = rhs }}) = (tvs, rhs)
889 newTyConRhs tycon = pprPanic "newTyConRhs" (ppr tycon)
891 newTyConEtadRhs :: TyCon -> ([TyVar], Type)
892 newTyConEtadRhs (AlgTyCon {algTcRhs = NewTyCon { nt_etad_rhs = tvs_rhs }}) = tvs_rhs
893 newTyConEtadRhs tycon = pprPanic "newTyConEtadRhs" (ppr tycon)
895 newTyConRep :: TyCon -> ([TyVar], Type)
896 newTyConRep (AlgTyCon {tyConTyVars = tvs, algTcRhs = NewTyCon { nt_rep = rep }}) = (tvs, rep)
897 newTyConRep tycon = pprPanic "newTyConRep" (ppr tycon)
899 newTyConCo_maybe :: TyCon -> Maybe TyCon
900 newTyConCo_maybe (AlgTyCon {algTcRhs = NewTyCon { nt_co = co }}) = co
901 newTyConCo_maybe _ = Nothing
903 tyConPrimRep :: TyCon -> PrimRep
904 tyConPrimRep (PrimTyCon {primTyConRep = rep}) = rep
905 tyConPrimRep tc = ASSERT(not (isUnboxedTupleTyCon tc)) PtrRep
909 tyConStupidTheta :: TyCon -> [PredType]
910 tyConStupidTheta (AlgTyCon {algTcStupidTheta = stupid}) = stupid
911 tyConStupidTheta (TupleTyCon {}) = []
912 tyConStupidTheta tycon = pprPanic "tyConStupidTheta" (ppr tycon)
916 synTyConDefn :: TyCon -> ([TyVar], Type)
917 synTyConDefn (SynTyCon {tyConTyVars = tyvars, synTcRhs = SynonymTyCon ty})
919 synTyConDefn tycon = pprPanic "getSynTyConDefn" (ppr tycon)
921 synTyConRhs :: TyCon -> SynTyConRhs
922 synTyConRhs (SynTyCon {synTcRhs = rhs}) = rhs
923 synTyConRhs tc = pprPanic "synTyConRhs" (ppr tc)
925 synTyConType :: TyCon -> Type
926 synTyConType tc = case synTcRhs tc of
928 _ -> pprPanic "synTyConType" (ppr tc)
930 synTyConResKind :: TyCon -> Kind
931 synTyConResKind (SynTyCon {synTcRhs = OpenSynTyCon kind _}) = kind
932 synTyConResKind tycon = pprPanic "synTyConResKind" (ppr tycon)
936 maybeTyConSingleCon :: TyCon -> Maybe DataCon
937 maybeTyConSingleCon (AlgTyCon {algTcRhs = DataTyCon {data_cons = [c] }}) = Just c
938 maybeTyConSingleCon (AlgTyCon {algTcRhs = NewTyCon { data_con = c }}) = Just c
939 maybeTyConSingleCon (AlgTyCon {}) = Nothing
940 maybeTyConSingleCon (TupleTyCon {dataCon = con}) = Just con
941 maybeTyConSingleCon (PrimTyCon {}) = Nothing
942 maybeTyConSingleCon (FunTyCon {}) = Nothing -- case at funty
943 maybeTyConSingleCon tc = pprPanic "maybeTyConSingleCon: unexpected tycon " $ ppr tc
947 isClassTyCon :: TyCon -> Bool
948 isClassTyCon (AlgTyCon {algTcParent = ClassTyCon _}) = True
949 isClassTyCon other_tycon = False
951 tyConClass_maybe :: TyCon -> Maybe Class
952 tyConClass_maybe (AlgTyCon {algTcParent = ClassTyCon clas}) = Just clas
953 tyConClass_maybe other_tycon = Nothing
955 isFamInstTyCon :: TyCon -> Bool
956 isFamInstTyCon (AlgTyCon {algTcParent = FamilyTyCon _ _ _ }) = True
957 isFamInstTyCon (SynTyCon {synTcParent = FamilyTyCon _ _ _ }) = True
958 isFamInstTyCon other_tycon = False
960 tyConFamInst_maybe :: TyCon -> Maybe (TyCon, [Type])
961 tyConFamInst_maybe (AlgTyCon {algTcParent = FamilyTyCon fam instTys _}) =
963 tyConFamInst_maybe (SynTyCon {synTcParent = FamilyTyCon fam instTys _}) =
965 tyConFamInst_maybe other_tycon =
968 tyConFamilyCoercion_maybe :: TyCon -> Maybe TyCon
969 tyConFamilyCoercion_maybe (AlgTyCon {algTcParent = FamilyTyCon _ _ coe}) =
971 tyConFamilyCoercion_maybe (SynTyCon {synTcParent = FamilyTyCon _ _ coe}) =
973 tyConFamilyCoercion_maybe other_tycon =
978 %************************************************************************
980 \subsection[TyCon-instances]{Instance declarations for @TyCon@}
982 %************************************************************************
984 @TyCon@s are compared by comparing their @Unique@s.
986 The strictness analyser needs @Ord@. It is a lexicographic order with
987 the property @(a<=b) || (b<=a)@.
990 instance Eq TyCon where
991 a == b = case (a `compare` b) of { EQ -> True; _ -> False }
992 a /= b = case (a `compare` b) of { EQ -> False; _ -> True }
994 instance Ord TyCon where
995 a <= b = case (a `compare` b) of { LT -> True; EQ -> True; GT -> False }
996 a < b = case (a `compare` b) of { LT -> True; EQ -> False; GT -> False }
997 a >= b = case (a `compare` b) of { LT -> False; EQ -> True; GT -> True }
998 a > b = case (a `compare` b) of { LT -> False; EQ -> False; GT -> True }
999 compare a b = getUnique a `compare` getUnique b
1001 instance Uniquable TyCon where
1002 getUnique tc = tyConUnique tc
1004 instance Outputable TyCon where
1005 ppr tc = ppr (getName tc)
1007 instance NamedThing TyCon where