2 % (c) The University of Glasgow 2006
3 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
10 -- * Main TyCon data types
13 AlgTyConRhs(..), visibleDataCons,
14 TyConParent(..), isNoParent,
18 -- ** Constructing TyCons
32 -- ** Predicates on TyCons
34 isClassTyCon, isFamInstTyCon,
37 isTupleTyCon, isUnboxedTupleTyCon, isBoxedTupleTyCon,
38 isSynTyCon, isClosedSynTyCon,
39 isSuperKindTyCon, isDecomposableTyCon,
40 isCoercionTyCon, isCoercionTyCon_maybe,
41 isForeignTyCon, isAnyTyCon, tyConHasKind,
44 isDataTyCon, isProductTyCon, isEnumerationTyCon,
45 isNewTyCon, isAbstractTyCon,
46 isFamilyTyCon, isSynFamilyTyCon, isDataFamilyTyCon,
52 isImplicitTyCon, tyConHasGenerics,
54 -- ** Extracting information out of TyCons
59 tyConDataCons, tyConDataCons_maybe, tyConSingleDataCon_maybe,
65 tyConFamInst_maybe, tyConFamilyCoercion_maybe,tyConFamInstSig_maybe,
66 synTyConDefn, synTyConRhs, synTyConType,
67 tyConExtName, -- External name for foreign types
69 newTyConRhs, newTyConEtadRhs, unwrapNewTyCon_maybe,
72 -- ** Manipulating TyCons
73 tcExpandTyCon_maybe, coreExpandTyCon_maybe,
77 -- * Primitive representations of Types
83 #include "HsVersions.h"
85 import {-# SOURCE #-} TypeRep ( Kind, Type, PredType )
86 import {-# SOURCE #-} DataCon ( DataCon, isVanillaDataCon )
98 import qualified Data.Data as Data
101 -----------------------------------------------
102 Notes about type families
103 -----------------------------------------------
105 Note [Type synonym families]
106 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
107 * Type synonym families, also known as "type functions", map directly
108 onto the type functions in FC:
111 type instance F Int = Bool
114 * Reply "yes" to isSynFamilyTyCon, and isFamilyTyCon
116 * From the user's point of view (F Int) and Bool are simply
119 * A Haskell 98 type synonym is a degenerate form of a type synonym
122 * Type functions can't appear in the LHS of a type function:
123 type instance F (F Int) = ... -- BAD!
125 * Translation of type family decl:
128 a SynTyCon 'F', whose SynTyConRhs is SynFamilyTyCon
130 * Translation of type instance decl:
131 type instance F [a] = Maybe a
133 A SynTyCon 'R:FList a', whose
134 SynTyConRhs is (SynonymTyCon (Maybe a))
135 TyConParent is (FamInstTyCon F [a] co)
136 where co :: F [a] ~ R:FList a
137 Notice that we introduce a gratuitous vanilla type synonym
138 type R:FList a = Maybe a
139 solely so that type and data families can be treated more
140 uniformly, via a single FamInstTyCon descriptor
142 * In the future we might want to support
143 * closed type families (esp when we have proper kinds)
144 * injective type families (allow decomposition)
145 but we don't at the moment [2010]
147 Note [Data type families]
148 ~~~~~~~~~~~~~~~~~~~~~~~~~
149 See also Note [Wrappers for data instance tycons] in MkId.lhs
151 * Data type families are declared thus
153 data instance T Int = T1 | T2 Bool
155 Here T is the "family TyCon".
157 * Reply "yes" to isDataFamilyTyCon, and isFamilyTyCon
159 * The user does not see any "equivalent types" as he did with type
160 synonym families. He just sees constructors with types
164 * Here's the FC version of the above declarations:
167 data R:TInt = T1 | T2 Bool
168 axiom ax_ti : T Int ~ R:TInt
170 The R:TInt is the "representation TyCons".
171 It has an AlgTyConParent of
172 FamInstTyCon T [Int] ax_ti
174 * The data contructor T2 has a wrapper (which is what the
175 source-level "T2" invokes):
177 $WT2 :: Bool -> T Int
178 $WT2 b = T2 b `cast` sym ax_ti
180 * A data instance can declare a fully-fledged GADT:
182 data instance T (a,b) where
184 X2 :: a -> b -> T (a,b)
186 Here's the FC version of the above declaration:
189 X1 :: R:TPair Int Bool
190 X2 :: a -> b -> R:TPair a b
191 axiom ax_pr :: T (a,b) ~ R:TPair a b
193 $WX1 :: forall a b. a -> b -> T (a,b)
194 $WX1 a b (x::a) (y::b) = X2 a b x y `cast` sym (ax_pr a b)
196 The R:TPair are the "representation TyCons".
197 We have a bit of work to do, to unpick the result types of the
198 data instance declaration for T (a,b), to get the result type in the
199 representation; e.g. T (a,b) --> R:TPair a b
201 The representation TyCon R:TList, has an AlgTyConParent of
203 FamInstTyCon T [(a,b)] ax_pr
205 * Notice that T is NOT translated to a FC type function; it just
206 becomes a "data type" with no constructors, which can be coerced inot
207 into R:TInt, R:TPair by the axioms. These axioms
208 axioms come into play when (and *only* when) you
209 - use a data constructor
210 - do pattern matching
211 Rather like newtype, in fact
215 - T behaves just like a data type so far as decomposition is concerned
217 - (T Int) is not implicitly converted to R:TInt during type inference.
218 Indeed the latter type is unknown to the programmer.
220 - There *is* an instance for (T Int) in the type-family instance
221 environment, but it is only used for overlap checking
223 - It's fine to have T in the LHS of a type function:
224 type instance F (T a) = [a]
226 It was this last point that confused me! The big thing is that you
227 should not think of a data family T as a *type function* at all, not
228 even an injective one! We can't allow even injective type functions
229 on the LHS of a type function:
230 type family injective G a :: *
231 type instance F (G Int) = Bool
232 is no good, even if G is injective, because consider
233 type instance G Int = Bool
234 type instance F Bool = Char
236 So a data type family is not an injective type function. It's just a
237 data type with some axioms that connect it to other data types.
239 %************************************************************************
241 \subsection{The data type}
243 %************************************************************************
246 -- | TyCons represent type constructors. Type constructors are introduced by things such as:
248 -- 1) Data declarations: @data Foo = ...@ creates the @Foo@ type constructor of kind @*@
250 -- 2) Type synonyms: @type Foo = ...@ creates the @Foo@ type constructor
252 -- 3) Newtypes: @newtype Foo a = MkFoo ...@ creates the @Foo@ type constructor of kind @* -> *@
254 -- 4) Class declarations: @class Foo where@ creates the @Foo@ type constructor of kind @*@
256 -- 5) Type coercions! This is because we represent a coercion from @t1@ to @t2@
257 -- as a 'Type', where that type has kind @t1 ~ t2@. See "Coercion" for more on this
259 -- This data type also encodes a number of primitive, built in type constructors such as those
260 -- for function and tuple types.
262 = -- | The function type constructor, @(->)@
264 tyConUnique :: Unique,
270 -- | Algebraic type constructors, which are defined to be those
271 -- arising @data@ type and @newtype@ declarations. All these
272 -- constructors are lifted and boxed. See 'AlgTyConRhs' for more
275 tyConUnique :: Unique,
280 tyConTyVars :: [TyVar], -- ^ The type variables used in the type constructor.
281 -- Invariant: length tyvars = arity
282 -- Precisely, this list scopes over:
284 -- 1. The 'algTcStupidTheta'
285 -- 2. The cached types in 'algTyConRhs.NewTyCon'
286 -- 3. The family instance types if present
288 -- Note that it does /not/ scope over the data constructors.
290 algTcGadtSyntax :: Bool, -- ^ Was the data type declared with GADT syntax?
291 -- If so, that doesn't mean it's a true GADT;
292 -- only that the "where" form was used.
293 -- This field is used only to guide pretty-printing
295 algTcStupidTheta :: [PredType], -- ^ The \"stupid theta\" for the data type
296 -- (always empty for GADTs).
297 -- A \"stupid theta\" is the context to the left
298 -- of an algebraic type declaration,
299 -- e.g. @Eq a@ in the declaration
300 -- @data Eq a => T a ...@.
302 algTcRhs :: AlgTyConRhs, -- ^ Contains information about the
303 -- data constructors of the algebraic type
305 algTcRec :: RecFlag, -- ^ Tells us whether the data type is part
306 -- of a mutually-recursive group or not
308 hasGenerics :: Bool, -- ^ Whether generic (in the -XGenerics sense)
309 -- to\/from functions are available in the exports
310 -- of the data type's source module.
312 algTcParent :: TyConParent -- ^ Gives the class or family declaration 'TyCon'
313 -- for derived 'TyCon's representing class
314 -- or family instances, respectively.
315 -- See also 'synTcParent'
318 -- | Represents the infinite family of tuple type constructors,
319 -- @()@, @(a,b)@, @(# a, b #)@ etc.
321 tyConUnique :: Unique,
325 tyConBoxed :: Boxity,
326 tyConTyVars :: [TyVar],
327 dataCon :: DataCon, -- ^ Corresponding tuple data constructor
331 -- | Represents type synonyms
333 tyConUnique :: Unique,
338 tyConTyVars :: [TyVar], -- Bound tyvars
340 synTcRhs :: SynTyConRhs, -- ^ Contains information about the
341 -- expansion of the synonym
343 synTcParent :: TyConParent -- ^ Gives the family declaration 'TyCon'
344 -- of 'TyCon's representing family instances
348 -- | Primitive types; cannot be defined in Haskell. This includes
349 -- the usual suspects (such as @Int#@) as well as foreign-imported
352 tyConUnique :: Unique,
355 tyConArity :: Arity, -- SLPJ Oct06: I'm not sure what the significance
356 -- of the arity of a primtycon is!
358 primTyConRep :: PrimRep, -- ^ Many primitive tycons are unboxed, but some are
359 -- boxed (represented by pointers). This 'PrimRep'
360 -- holds that information.
361 -- Only relevant if tc_kind = *
363 isUnLifted :: Bool, -- ^ Most primitive tycons are unlifted
364 -- (may not contain bottom)
365 -- but foreign-imported ones may be lifted
367 tyConExtName :: Maybe FastString -- ^ @Just e@ for foreign-imported types,
368 -- holds the name of the imported thing
371 -- | Type coercions, such as @(~)@, @sym@, @trans@, @left@ and @right@.
372 -- INVARIANT: Coercion TyCons are always fully applied
373 -- But note that a CoTyCon can be *over*-saturated in a type.
374 -- E.g. (sym g1) Int will be represented as (TyConApp sym [g1,Int])
376 tyConUnique :: Unique,
379 coTcDesc :: CoTyConDesc
382 -- | Any types. Like tuples, this is a potentially-infinite family of TyCons
383 -- one for each distinct Kind. They have no values at all.
384 -- Because there are infinitely many of them (like tuples) they are
385 -- defined in GHC.Prim and have names like "Any(*->*)".
386 -- Their Unique is derived from the OccName.
387 -- See Note [Any types] in TysPrim
389 tyConUnique :: Unique,
391 tc_kind :: Kind -- Never = *; that is done via PrimTyCon
392 -- See Note [Any types] in TysPrim
395 -- | Super-kinds. These are "kinds-of-kinds" and are never seen in
396 -- Haskell source programs. There are only two super-kinds: TY (aka
397 -- "box"), which is the super-kind of kinds that construct types
398 -- eventually, and CO (aka "diamond"), which is the super-kind of
399 -- kinds that just represent coercions.
401 -- Super-kinds have no kind themselves, and have arity zero
403 tyConUnique :: Unique,
407 -- | Names of the fields in an algebraic record type
408 type FieldLabel = Name
410 -- | Represents right-hand-sides of 'TyCon's for algebraic types
413 -- | Says that we know nothing about this data type, except that
414 -- it's represented by a pointer. Used when we export a data type
415 -- abstractly into an .hi file.
418 -- | Represents an open type family without a fixed right hand
419 -- side. Additional instances can appear at any time.
421 -- These are introduced by either a top level declaration:
425 -- Or an associated data type declaration, within a class declaration:
427 -- > class C a b where
431 -- | Information about those 'TyCon's derived from a @data@
432 -- declaration. This includes data types with no constructors at
435 data_cons :: [DataCon],
436 -- ^ The data type constructors; can be empty if the user
437 -- declares the type to have no constructors
439 -- INVARIANT: Kept in order of increasing 'DataCon' tag
440 -- (see the tag assignment in DataCon.mkDataCon)
442 is_enum :: Bool -- ^ Cached value: is this an enumeration type?
443 -- (See 'isEnumerationTyCon')
446 -- | Information about those 'TyCon's derived from a @newtype@ declaration
448 data_con :: DataCon, -- ^ The unique constructor for the @newtype@.
449 -- It has no existentials
451 nt_rhs :: Type, -- ^ Cached value: the argument type of the constructor,
452 -- which is just the representation type of the 'TyCon'
453 -- (remember that @newtype@s do not exist at runtime
454 -- so need a different representation type).
456 -- The free 'TyVar's of this type are the 'tyConTyVars'
457 -- from the corresponding 'TyCon'
459 nt_etad_rhs :: ([TyVar], Type),
460 -- ^ Same as the 'nt_rhs', but this time eta-reduced.
461 -- Hence the list of 'TyVar's in this field may be
462 -- shorter than the declared arity of the 'TyCon'.
464 -- See Note [Newtype eta]
466 nt_co :: Maybe TyCon -- ^ A 'TyCon' (which is always a 'CoTyCon') that can
467 -- have a 'Coercion' extracted from it to create
468 -- the @newtype@ from the representation 'Type'.
470 -- This field is optional for non-recursive @newtype@s only.
472 -- See Note [Newtype coercions]
473 -- Invariant: arity = #tvs in nt_etad_rhs;
474 -- See Note [Newtype eta]
475 -- Watch out! If any newtypes become transparent
476 -- again check Trac #1072.
479 -- | Extract those 'DataCon's that we are able to learn about. Note
480 -- that visibility in this sense does not correspond to visibility in
481 -- the context of any particular user program!
482 visibleDataCons :: AlgTyConRhs -> [DataCon]
483 visibleDataCons AbstractTyCon = []
484 visibleDataCons DataFamilyTyCon {} = []
485 visibleDataCons (DataTyCon{ data_cons = cs }) = cs
486 visibleDataCons (NewTyCon{ data_con = c }) = [c]
488 -- ^ Both type classes as well as family instances imply implicit
489 -- type constructors. These implicit type constructors refer to their parent
490 -- structure (ie, the class or family from which they derive) using a type of
491 -- the following form. We use 'TyConParent' for both algebraic and synonym
492 -- types, but the variant 'ClassTyCon' will only be used by algebraic 'TyCon's.
494 = -- | An ordinary type constructor has no parent.
497 -- | Type constructors representing a class dictionary.
499 Class -- INVARIANT: the classTyCon of this Class is the current tycon
501 -- | An *associated* type of a class.
503 Class -- The class in whose declaration the family is declared
505 -- | Type constructors representing an instance of a type family. Parameters:
507 -- 1) The type family in question
509 -- 2) Instance types; free variables are the 'tyConTyVars'
510 -- of the current 'TyCon' (not the family one). INVARIANT:
511 -- the number of types matches the arity of the family 'TyCon'
513 -- 3) A 'CoTyCon' identifying the representation
514 -- type with the type instance family
515 | FamInstTyCon -- See Note [Data type families]
516 -- and Note [Type synonym families]
517 TyCon -- The family TyCon
518 [Type] -- Argument types (mentions the tyConTyVars of this TyCon)
519 TyCon -- The coercion constructor
521 -- E.g. data intance T [a] = ...
522 -- gives a representation tycon:
523 -- data R:TList a = ...
524 -- axiom co a :: T [a] ~ R:TList a
525 -- with R:TList's algTcParent = FamInstTyCon T [a] co
527 -- | Checks the invariants of a 'TyConParent' given the appropriate type class name, if any
528 okParent :: Name -> TyConParent -> Bool
529 okParent _ NoParentTyCon = True
530 okParent tc_name (AssocFamilyTyCon cls) = tc_name `elem` map tyConName (classATs cls)
531 okParent tc_name (ClassTyCon cls) = tc_name == tyConName (classTyCon cls)
532 okParent _ (FamInstTyCon fam_tc tys _co_tc) = tyConArity fam_tc == length tys
534 isNoParent :: TyConParent -> Bool
535 isNoParent NoParentTyCon = True
540 -- | Information pertaining to the expansion of a type synonym (@type@)
542 = SynonymTyCon -- ^ An ordinary type synony
543 Type -- ^ The rhs, which mentions head type variables. It acts as a
544 -- template for the expansion when the 'TyCon' is applied to some
547 | SynFamilyTyCon -- A type synonym family e.g. type family F x y :: * -> *
553 | CoCsel1 | CoCsel2 | CoCselR
556 | CoAxiom -- C tvs : F lhs-tys ~ rhs-ty
557 { co_ax_tvs :: [TyVar]
559 , co_ax_rhs :: Type }
564 Note [Newtype coercions]
565 ~~~~~~~~~~~~~~~~~~~~~~~~
566 The NewTyCon field nt_co is a a TyCon (a coercion constructor in fact)
567 which is used for coercing from the representation type of the
568 newtype, to the newtype itself. For example,
570 newtype T a = MkT (a -> a)
572 the NewTyCon for T will contain nt_co = CoT where CoT t : T t ~ t ->
573 t. This TyCon is a CoTyCon, so it does not have a kind on its
574 own; it basically has its own typing rule for the fully-applied
575 version. If the newtype T has k type variables then CoT has arity at
576 most k. In the case that the right hand side is a type application
577 ending with the same type variables as the left hand side, we
578 "eta-contract" the coercion. So if we had
580 newtype S a = MkT [a]
582 then we would generate the arity 0 coercion CoS : S ~ []. The
583 primary reason we do this is to make newtype deriving cleaner.
585 In the paper we'd write
586 axiom CoT : (forall t. T t) ~ (forall t. [t])
587 and then when we used CoT at a particular type, s, we'd say
589 which encodes as (TyConApp instCoercionTyCon [TyConApp CoT [], s])
591 But in GHC we instead make CoT into a new piece of type syntax, CoTyCon,
592 (like instCoercionTyCon, symCoercionTyCon etc), which must always
593 be saturated, but which encodes as
595 In the vocabulary of the paper it's as if we had axiom declarations
597 axiom CoT t : T t ~ [t]
602 newtype Parser m a = MkParser (Foogle m a)
603 Are these two types equal (to Core)?
606 Well, yes. But to see that easily we eta-reduce the RHS type of
607 Parser, in this case to ([], Froogle), so that even unsaturated applications
608 of Parser will work right. This eta reduction is done when the type
609 constructor is built, and cached in NewTyCon. The cached field is
610 only used in coreExpandTyCon_maybe.
612 Here's an example that I think showed up in practice
614 newtype T a = MkT [a]
615 newtype Foo m = MkFoo (forall a. m a -> Int)
621 w2 = MkFoo (\(MkT x) -> case w1 of MkFoo f -> f x)
623 After desugaring, and discarding the data constructors for the newtypes,
627 And now Lint complains unless Foo T == Foo [], and that requires T==[]
629 This point carries over to the newtype coercion, because we need to
631 w2 = w1 `cast` Foo CoT
633 so the coercion tycon CoT must have
638 %************************************************************************
642 %************************************************************************
644 A PrimRep is somewhat similar to a CgRep (see codeGen/SMRep) and a
645 MachRep (see cmm/CmmExpr), although each of these types has a distinct
646 and clearly defined purpose:
648 - A PrimRep is a CgRep + information about signedness + information
649 about primitive pointers (AddrRep). Signedness and primitive
650 pointers are required when passing a primitive type to a foreign
651 function, but aren't needed for call/return conventions of Haskell
654 - A MachRep is a basic machine type (non-void, doesn't contain
655 information on pointerhood or signedness, but contains some
656 reps that don't have corresponding Haskell types).
659 -- | A 'PrimRep' is an abstraction of a type. It contains information that
660 -- the code generator needs in order to pass arguments, return results,
661 -- and store values of this type.
665 | IntRep -- ^ Signed, word-sized value
666 | WordRep -- ^ Unsigned, word-sized value
667 | Int64Rep -- ^ Signed, 64 bit value (with 32-bit words only)
668 | Word64Rep -- ^ Unsigned, 64 bit value (with 32-bit words only)
669 | AddrRep -- ^ A pointer, but /not/ to a Haskell value (use 'PtrRep')
674 instance Outputable PrimRep where
675 ppr r = text (show r)
677 -- | Find the size of a 'PrimRep', in words
678 primRepSizeW :: PrimRep -> Int
679 primRepSizeW IntRep = 1
680 primRepSizeW WordRep = 1
681 primRepSizeW Int64Rep = wORD64_SIZE `quot` wORD_SIZE
682 primRepSizeW Word64Rep= wORD64_SIZE `quot` wORD_SIZE
683 primRepSizeW FloatRep = 1 -- NB. might not take a full word
684 primRepSizeW DoubleRep= dOUBLE_SIZE `quot` wORD_SIZE
685 primRepSizeW AddrRep = 1
686 primRepSizeW PtrRep = 1
687 primRepSizeW VoidRep = 0
690 %************************************************************************
692 \subsection{TyCon Construction}
694 %************************************************************************
696 Note: the TyCon constructors all take a Kind as one argument, even though
697 they could, in principle, work out their Kind from their other arguments.
698 But to do so they need functions from Types, and that makes a nasty
699 module mutual-recursion. And they aren't called from many places.
700 So we compromise, and move their Kind calculation to the call site.
703 -- | Given the name of the function type constructor and it's kind, create the
704 -- corresponding 'TyCon'. It is reccomended to use 'TypeRep.funTyCon' if you want
705 -- this functionality
706 mkFunTyCon :: Name -> Kind -> TyCon
709 tyConUnique = nameUnique name,
715 -- | This is the making of an algebraic 'TyCon'. Notably, you have to
716 -- pass in the generic (in the -XGenerics sense) information about the
717 -- type constructor - you can get hold of it easily (see Generics
720 -> Kind -- ^ Kind of the resulting 'TyCon'
721 -> [TyVar] -- ^ 'TyVar's scoped over: see 'tyConTyVars'.
722 -- Arity is inferred from the length of this list
723 -> [PredType] -- ^ Stupid theta: see 'algTcStupidTheta'
724 -> AlgTyConRhs -- ^ Information about dat aconstructors
726 -> RecFlag -- ^ Is the 'TyCon' recursive?
727 -> Bool -- ^ Does it have generic functions? See 'hasGenerics'
728 -> Bool -- ^ Was the 'TyCon' declared with GADT syntax?
730 mkAlgTyCon name kind tyvars stupid rhs parent is_rec gen_info gadt_syn
733 tyConUnique = nameUnique name,
735 tyConArity = length tyvars,
736 tyConTyVars = tyvars,
737 algTcStupidTheta = stupid,
739 algTcParent = ASSERT( okParent name parent ) parent,
741 algTcGadtSyntax = gadt_syn,
742 hasGenerics = gen_info
745 -- | Simpler specialization of 'mkAlgTyCon' for classes
746 mkClassTyCon :: Name -> Kind -> [TyVar] -> AlgTyConRhs -> Class -> RecFlag -> TyCon
747 mkClassTyCon name kind tyvars rhs clas is_rec =
748 mkAlgTyCon name kind tyvars [] rhs (ClassTyCon clas) is_rec False False
751 -> Kind -- ^ Kind of the resulting 'TyCon'
752 -> Arity -- ^ Arity of the tuple
753 -> [TyVar] -- ^ 'TyVar's scoped over: see 'tyConTyVars'
755 -> Boxity -- ^ Whether the tuple is boxed or unboxed
756 -> Bool -- ^ Does it have generic functions? See 'hasGenerics'
758 mkTupleTyCon name kind arity tyvars con boxed gen_info
760 tyConUnique = nameUnique name,
765 tyConTyVars = tyvars,
767 hasGenerics = gen_info
770 -- ^ Foreign-imported (.NET) type constructors are represented
771 -- as primitive, but /lifted/, 'TyCons' for now. They are lifted
772 -- because the Haskell type @T@ representing the (foreign) .NET
773 -- type @T@ is actually implemented (in ILX) as a @thunk<T>@
774 mkForeignTyCon :: Name
775 -> Maybe FastString -- ^ Name of the foreign imported thing, maybe
779 mkForeignTyCon name ext_name kind arity
782 tyConUnique = nameUnique name,
785 primTyConRep = PtrRep, -- they all do
787 tyConExtName = ext_name
791 -- | Create an unlifted primitive 'TyCon', such as @Int#@
792 mkPrimTyCon :: Name -> Kind -> Arity -> PrimRep -> TyCon
793 mkPrimTyCon name kind arity rep
794 = mkPrimTyCon' name kind arity rep True
796 -- | Kind constructors
797 mkKindTyCon :: Name -> Kind -> TyCon
798 mkKindTyCon name kind
799 = mkPrimTyCon' name kind 0 VoidRep True
801 -- | Create a lifted primitive 'TyCon' such as @RealWorld@
802 mkLiftedPrimTyCon :: Name -> Kind -> Arity -> PrimRep -> TyCon
803 mkLiftedPrimTyCon name kind arity rep
804 = mkPrimTyCon' name kind arity rep False
806 mkPrimTyCon' :: Name -> Kind -> Arity -> PrimRep -> Bool -> TyCon
807 mkPrimTyCon' name kind arity rep is_unlifted
810 tyConUnique = nameUnique name,
814 isUnLifted = is_unlifted,
815 tyConExtName = Nothing
818 -- | Create a type synonym 'TyCon'
819 mkSynTyCon :: Name -> Kind -> [TyVar] -> SynTyConRhs -> TyConParent -> TyCon
820 mkSynTyCon name kind tyvars rhs parent
823 tyConUnique = nameUnique name,
825 tyConArity = length tyvars,
826 tyConTyVars = tyvars,
831 -- | Create a coercion 'TyCon'
832 mkCoercionTyCon :: Name -> Arity
835 mkCoercionTyCon name arity desc
838 tyConUnique = nameUnique name,
842 mkAnyTyCon :: Name -> Kind -> TyCon
844 = AnyTyCon { tyConName = name,
846 tyConUnique = nameUnique name }
848 -- | Create a super-kind 'TyCon'
849 mkSuperKindTyCon :: Name -> TyCon -- Super kinds always have arity zero
850 mkSuperKindTyCon name
853 tyConUnique = nameUnique name
858 isFunTyCon :: TyCon -> Bool
859 isFunTyCon (FunTyCon {}) = True
862 -- | Test if the 'TyCon' is algebraic but abstract (invisible data constructors)
863 isAbstractTyCon :: TyCon -> Bool
864 isAbstractTyCon (AlgTyCon { algTcRhs = AbstractTyCon }) = True
865 isAbstractTyCon _ = False
867 -- | Make an algebraic 'TyCon' abstract. Panics if the supplied 'TyCon' is not algebraic
868 makeTyConAbstract :: TyCon -> TyCon
869 makeTyConAbstract tc@(AlgTyCon {}) = tc { algTcRhs = AbstractTyCon }
870 makeTyConAbstract tc = pprPanic "makeTyConAbstract" (ppr tc)
872 -- | Does this 'TyCon' represent something that cannot be defined in Haskell?
873 isPrimTyCon :: TyCon -> Bool
874 isPrimTyCon (PrimTyCon {}) = True
875 isPrimTyCon _ = False
877 -- | Is this 'TyCon' unlifted (i.e. cannot contain bottom)? Note that this can only
878 -- be true for primitive and unboxed-tuple 'TyCon's
879 isUnLiftedTyCon :: TyCon -> Bool
880 isUnLiftedTyCon (PrimTyCon {isUnLifted = is_unlifted}) = is_unlifted
881 isUnLiftedTyCon (TupleTyCon {tyConBoxed = boxity}) = not (isBoxed boxity)
882 isUnLiftedTyCon _ = False
884 -- | Returns @True@ if the supplied 'TyCon' resulted from either a
885 -- @data@ or @newtype@ declaration
886 isAlgTyCon :: TyCon -> Bool
887 isAlgTyCon (AlgTyCon {}) = True
888 isAlgTyCon (TupleTyCon {}) = True
891 isDataTyCon :: TyCon -> Bool
892 -- ^ Returns @True@ for data types that are /definitely/ represented by
893 -- heap-allocated constructors. These are scrutinised by Core-level
894 -- @case@ expressions, and they get info tables allocated for them.
896 -- Generally, the function will be true for all @data@ types and false
897 -- for @newtype@s, unboxed tuples and type family 'TyCon's. But it is
898 -- not guarenteed to return @True@ in all cases that it could.
900 -- NB: for a data type family, only the /instance/ 'TyCon's
901 -- get an info table. The family declaration 'TyCon' does not
902 isDataTyCon (AlgTyCon {algTcRhs = rhs})
904 DataFamilyTyCon {} -> False
907 AbstractTyCon -> False -- We don't know, so return False
908 isDataTyCon (TupleTyCon {tyConBoxed = boxity}) = isBoxed boxity
909 isDataTyCon _ = False
911 -- | Is this 'TyCon' that for a @newtype@
912 isNewTyCon :: TyCon -> Bool
913 isNewTyCon (AlgTyCon {algTcRhs = NewTyCon {}}) = True
916 -- | Take a 'TyCon' apart into the 'TyVar's it scopes over, the 'Type' it expands
917 -- into, and (possibly) a coercion from the representation type to the @newtype@.
918 -- Returns @Nothing@ if this is not possible.
919 unwrapNewTyCon_maybe :: TyCon -> Maybe ([TyVar], Type, Maybe TyCon)
920 unwrapNewTyCon_maybe (AlgTyCon { tyConTyVars = tvs,
921 algTcRhs = NewTyCon { nt_co = mb_co,
923 = Just (tvs, rhs, mb_co)
924 unwrapNewTyCon_maybe _ = Nothing
926 isProductTyCon :: TyCon -> Bool
927 -- | A /product/ 'TyCon' must both:
929 -- 1. Have /one/ constructor
931 -- 2. /Not/ be existential
933 -- However other than this there are few restrictions: they may be @data@ or @newtype@
934 -- 'TyCon's of any boxity and may even be recursive.
935 isProductTyCon tc@(AlgTyCon {}) = case algTcRhs tc of
936 DataTyCon{ data_cons = [data_con] }
937 -> isVanillaDataCon data_con
940 isProductTyCon (TupleTyCon {}) = True
941 isProductTyCon _ = False
943 -- | Is this a 'TyCon' representing a type synonym (@type@)?
944 isSynTyCon :: TyCon -> Bool
945 isSynTyCon (SynTyCon {}) = True
948 -- As for newtypes, it is in some contexts important to distinguish between
949 -- closed synonyms and synonym families, as synonym families have no unique
950 -- right hand side to which a synonym family application can expand.
953 isDecomposableTyCon :: TyCon -> Bool
954 -- True iff we can decompose (T a b c) into ((T a b) c)
955 -- Specifically NOT true of synonyms (open and otherwise) and coercions
956 isDecomposableTyCon (SynTyCon {}) = False
957 isDecomposableTyCon (CoTyCon {}) = False
958 isDecomposableTyCon _other = True
960 -- | Is this an algebraic 'TyCon' declared with the GADT syntax?
961 isGadtSyntaxTyCon :: TyCon -> Bool
962 isGadtSyntaxTyCon (AlgTyCon { algTcGadtSyntax = res }) = res
963 isGadtSyntaxTyCon _ = False
965 -- | Is this an algebraic 'TyCon' which is just an enumeration of values?
966 isEnumerationTyCon :: TyCon -> Bool
967 isEnumerationTyCon (AlgTyCon {algTcRhs = DataTyCon { is_enum = res }}) = res
968 isEnumerationTyCon (TupleTyCon {tyConArity = arity}) = arity == 0
969 isEnumerationTyCon _ = False
971 -- | Is this a 'TyCon', synonym or otherwise, that may have further instances appear?
972 isFamilyTyCon :: TyCon -> Bool
973 isFamilyTyCon (SynTyCon {synTcRhs = SynFamilyTyCon {}}) = True
974 isFamilyTyCon (AlgTyCon {algTcRhs = DataFamilyTyCon {}}) = True
975 isFamilyTyCon _ = False
977 -- | Is this a synonym 'TyCon' that can have may have further instances appear?
978 isSynFamilyTyCon :: TyCon -> Bool
979 isSynFamilyTyCon (SynTyCon {synTcRhs = SynFamilyTyCon {}}) = True
980 isSynFamilyTyCon _ = False
982 -- | Is this a synonym 'TyCon' that can have may have further instances appear?
983 isDataFamilyTyCon :: TyCon -> Bool
984 isDataFamilyTyCon (AlgTyCon {algTcRhs = DataFamilyTyCon {}}) = True
985 isDataFamilyTyCon _ = False
987 -- | Is this a synonym 'TyCon' that can have no further instances appear?
988 isClosedSynTyCon :: TyCon -> Bool
989 isClosedSynTyCon tycon = isSynTyCon tycon && not (isFamilyTyCon tycon)
991 -- | Injective 'TyCon's can be decomposed, so that
992 -- T ty1 ~ T ty2 => ty1 ~ ty2
993 isInjectiveTyCon :: TyCon -> Bool
994 isInjectiveTyCon tc = not (isSynTyCon tc)
995 -- Ultimately we may have injective associated types
996 -- in which case this test will become more interesting
998 -- It'd be unusual to call isInjectiveTyCon on a regular H98
999 -- type synonym, because you should probably have expanded it first
1000 -- But regardless, it's not injective!
1002 -- | Are we able to extract informationa 'TyVar' to class argument list
1003 -- mappping from a given 'TyCon'?
1004 isTyConAssoc :: TyCon -> Bool
1005 isTyConAssoc tc = case tyConParent tc of
1006 AssocFamilyTyCon {} -> True
1009 -- The unit tycon didn't used to be classed as a tuple tycon
1010 -- but I thought that was silly so I've undone it
1011 -- If it can't be for some reason, it should be a AlgTyCon
1012 isTupleTyCon :: TyCon -> Bool
1013 -- ^ Does this 'TyCon' represent a tuple?
1015 -- NB: when compiling @Data.Tuple@, the tycons won't reply @True@ to
1016 -- 'isTupleTyCon', becuase they are built as 'AlgTyCons'. However they
1017 -- get spat into the interface file as tuple tycons, so I don't think
1019 isTupleTyCon (TupleTyCon {}) = True
1020 isTupleTyCon _ = False
1022 -- | Is this the 'TyCon' for an unboxed tuple?
1023 isUnboxedTupleTyCon :: TyCon -> Bool
1024 isUnboxedTupleTyCon (TupleTyCon {tyConBoxed = boxity}) = not (isBoxed boxity)
1025 isUnboxedTupleTyCon _ = False
1027 -- | Is this the 'TyCon' for a boxed tuple?
1028 isBoxedTupleTyCon :: TyCon -> Bool
1029 isBoxedTupleTyCon (TupleTyCon {tyConBoxed = boxity}) = isBoxed boxity
1030 isBoxedTupleTyCon _ = False
1032 -- | Extract the boxity of the given 'TyCon', if it is a 'TupleTyCon'.
1034 tupleTyConBoxity :: TyCon -> Boxity
1035 tupleTyConBoxity tc = tyConBoxed tc
1037 -- | Is this a recursive 'TyCon'?
1038 isRecursiveTyCon :: TyCon -> Bool
1039 isRecursiveTyCon (AlgTyCon {algTcRec = Recursive}) = True
1040 isRecursiveTyCon _ = False
1042 -- | Did this 'TyCon' originate from type-checking a .h*-boot file?
1043 isHiBootTyCon :: TyCon -> Bool
1044 -- Used for knot-tying in hi-boot files
1045 isHiBootTyCon (AlgTyCon {algTcRhs = AbstractTyCon}) = True
1046 isHiBootTyCon _ = False
1048 -- | Is this the 'TyCon' of a foreign-imported type constructor?
1049 isForeignTyCon :: TyCon -> Bool
1050 isForeignTyCon (PrimTyCon {tyConExtName = Just _}) = True
1051 isForeignTyCon _ = False
1053 -- | Is this a super-kind 'TyCon'?
1054 isSuperKindTyCon :: TyCon -> Bool
1055 isSuperKindTyCon (SuperKindTyCon {}) = True
1056 isSuperKindTyCon _ = False
1058 -- | Is this an AnyTyCon?
1059 isAnyTyCon :: TyCon -> Bool
1060 isAnyTyCon (AnyTyCon {}) = True
1061 isAnyTyCon _ = False
1063 -- | Attempt to pull a 'TyCon' apart into the arity and 'coKindFun' of
1064 -- a coercion 'TyCon'. Returns @Nothing@ if the 'TyCon' is not of the
1066 isCoercionTyCon_maybe :: TyCon -> Maybe (Arity, CoTyConDesc)
1067 isCoercionTyCon_maybe (CoTyCon {tyConArity = ar, coTcDesc = desc})
1069 isCoercionTyCon_maybe _ = Nothing
1071 -- | Is this a 'TyCon' that represents a coercion?
1072 isCoercionTyCon :: TyCon -> Bool
1073 isCoercionTyCon (CoTyCon {}) = True
1074 isCoercionTyCon _ = False
1076 -- | Identifies implicit tycons that, in particular, do not go into interface
1077 -- files (because they are implicitly reconstructed when the interface is
1082 -- * Associated families are implicit, as they are re-constructed from
1083 -- the class declaration in which they reside, and
1085 -- * Family instances are /not/ implicit as they represent the instance body
1086 -- (similar to a @dfun@ does that for a class instance).
1087 isImplicitTyCon :: TyCon -> Bool
1088 isImplicitTyCon tycon | isTyConAssoc tycon = True
1089 | isSynTyCon tycon = False
1090 | isAlgTyCon tycon = isClassTyCon tycon ||
1092 isImplicitTyCon _other = True
1093 -- catches: FunTyCon, PrimTyCon,
1094 -- CoTyCon, SuperKindTyCon
1098 -----------------------------------------------
1099 -- Expand type-constructor applications
1100 -----------------------------------------------
1103 tcExpandTyCon_maybe, coreExpandTyCon_maybe
1105 -> [Type] -- ^ Arguments to 'TyCon'
1106 -> Maybe ([(TyVar,Type)],
1108 [Type]) -- ^ Returns a 'TyVar' substitution, the body type
1109 -- of the synonym (not yet substituted) and any arguments
1110 -- remaining from the application
1112 -- ^ Used to create the view the /typechecker/ has on 'TyCon's. We expand (closed) synonyms only, cf. 'coreExpandTyCon_maybe'
1113 tcExpandTyCon_maybe (SynTyCon {tyConTyVars = tvs,
1114 synTcRhs = SynonymTyCon rhs }) tys
1115 = expand tvs rhs tys
1116 tcExpandTyCon_maybe _ _ = Nothing
1120 -- ^ Used to create the view /Core/ has on 'TyCon's. We expand not only closed synonyms like 'tcExpandTyCon_maybe',
1121 -- but also non-recursive @newtype@s
1122 coreExpandTyCon_maybe (AlgTyCon {
1123 algTcRhs = NewTyCon { nt_etad_rhs = etad_rhs, nt_co = Nothing }}) tys
1124 = case etad_rhs of -- Don't do this in the pattern match, lest we accidentally
1125 -- match the etad_rhs of a *recursive* newtype
1126 (tvs,rhs) -> expand tvs rhs tys
1128 coreExpandTyCon_maybe tycon tys = tcExpandTyCon_maybe tycon tys
1132 expand :: [TyVar] -> Type -- Template
1134 -> Maybe ([(TyVar,Type)], Type, [Type]) -- Expansion
1136 = case n_tvs `compare` length tys of
1137 LT -> Just (tvs `zip` tys, rhs, drop n_tvs tys)
1138 EQ -> Just (tvs `zip` tys, rhs, [])
1145 -- | Does this 'TyCon' have any generic to\/from functions available? See also 'hasGenerics'
1146 tyConHasGenerics :: TyCon -> Bool
1147 tyConHasGenerics (AlgTyCon {hasGenerics = hg}) = hg
1148 tyConHasGenerics (TupleTyCon {hasGenerics = hg}) = hg
1149 tyConHasGenerics _ = False -- Synonyms
1151 tyConKind :: TyCon -> Kind
1152 tyConKind (FunTyCon { tc_kind = k }) = k
1153 tyConKind (AlgTyCon { tc_kind = k }) = k
1154 tyConKind (TupleTyCon { tc_kind = k }) = k
1155 tyConKind (SynTyCon { tc_kind = k }) = k
1156 tyConKind (PrimTyCon { tc_kind = k }) = k
1157 tyConKind (AnyTyCon { tc_kind = k }) = k
1158 tyConKind tc = pprPanic "tyConKind" (ppr tc) -- SuperKindTyCon and CoTyCon
1160 tyConHasKind :: TyCon -> Bool
1161 tyConHasKind (SuperKindTyCon {}) = False
1162 tyConHasKind (CoTyCon {}) = False
1163 tyConHasKind _ = True
1165 -- | As 'tyConDataCons_maybe', but returns the empty list of constructors if no constructors
1167 tyConDataCons :: TyCon -> [DataCon]
1168 -- It's convenient for tyConDataCons to return the
1169 -- empty list for type synonyms etc
1170 tyConDataCons tycon = tyConDataCons_maybe tycon `orElse` []
1172 -- | Determine the 'DataCon's originating from the given 'TyCon', if the 'TyCon' is the
1173 -- sort that can have any constructors (note: this does not include abstract algebraic types)
1174 tyConDataCons_maybe :: TyCon -> Maybe [DataCon]
1175 tyConDataCons_maybe (AlgTyCon {algTcRhs = DataTyCon { data_cons = cons }}) = Just cons
1176 tyConDataCons_maybe (AlgTyCon {algTcRhs = NewTyCon { data_con = con }}) = Just [con]
1177 tyConDataCons_maybe (TupleTyCon {dataCon = con}) = Just [con]
1178 tyConDataCons_maybe _ = Nothing
1180 -- | Determine the number of value constructors a 'TyCon' has. Panics if the 'TyCon'
1181 -- is not algebraic or a tuple
1182 tyConFamilySize :: TyCon -> Int
1183 tyConFamilySize (AlgTyCon {algTcRhs = DataTyCon {data_cons = cons}}) =
1185 tyConFamilySize (AlgTyCon {algTcRhs = NewTyCon {}}) = 1
1186 tyConFamilySize (AlgTyCon {algTcRhs = DataFamilyTyCon {}}) = 0
1187 tyConFamilySize (TupleTyCon {}) = 1
1188 tyConFamilySize other = pprPanic "tyConFamilySize:" (ppr other)
1190 -- | Extract an 'AlgTyConRhs' with information about data constructors from an algebraic or tuple
1191 -- 'TyCon'. Panics for any other sort of 'TyCon'
1192 algTyConRhs :: TyCon -> AlgTyConRhs
1193 algTyConRhs (AlgTyCon {algTcRhs = rhs}) = rhs
1194 algTyConRhs (TupleTyCon {dataCon = con, tyConArity = arity})
1195 = DataTyCon { data_cons = [con], is_enum = arity == 0 }
1196 algTyConRhs other = pprPanic "algTyConRhs" (ppr other)
1200 -- | Extract the bound type variables and type expansion of a type synonym 'TyCon'. Panics if the
1201 -- 'TyCon' is not a synonym
1202 newTyConRhs :: TyCon -> ([TyVar], Type)
1203 newTyConRhs (AlgTyCon {tyConTyVars = tvs, algTcRhs = NewTyCon { nt_rhs = rhs }}) = (tvs, rhs)
1204 newTyConRhs tycon = pprPanic "newTyConRhs" (ppr tycon)
1206 -- | Extract the bound type variables and type expansion of an eta-contracted type synonym 'TyCon'.
1207 -- Panics if the 'TyCon' is not a synonym
1208 newTyConEtadRhs :: TyCon -> ([TyVar], Type)
1209 newTyConEtadRhs (AlgTyCon {algTcRhs = NewTyCon { nt_etad_rhs = tvs_rhs }}) = tvs_rhs
1210 newTyConEtadRhs tycon = pprPanic "newTyConEtadRhs" (ppr tycon)
1212 -- | Extracts the @newtype@ coercion from such a 'TyCon', which can be used to construct something
1213 -- with the @newtype@s type from its representation type (right hand side). If the supplied 'TyCon'
1214 -- is not a @newtype@, returns @Nothing@
1215 newTyConCo_maybe :: TyCon -> Maybe TyCon
1216 newTyConCo_maybe (AlgTyCon {algTcRhs = NewTyCon { nt_co = co }}) = co
1217 newTyConCo_maybe _ = Nothing
1219 -- | Find the primitive representation of a 'TyCon'
1220 tyConPrimRep :: TyCon -> PrimRep
1221 tyConPrimRep (PrimTyCon {primTyConRep = rep}) = rep
1222 tyConPrimRep tc = ASSERT(not (isUnboxedTupleTyCon tc)) PtrRep
1226 -- | Find the \"stupid theta\" of the 'TyCon'. A \"stupid theta\" is the context to the left of
1227 -- an algebraic type declaration, e.g. @Eq a@ in the declaration @data Eq a => T a ...@
1228 tyConStupidTheta :: TyCon -> [PredType]
1229 tyConStupidTheta (AlgTyCon {algTcStupidTheta = stupid}) = stupid
1230 tyConStupidTheta (TupleTyCon {}) = []
1231 tyConStupidTheta tycon = pprPanic "tyConStupidTheta" (ppr tycon)
1235 -- | Extract the 'TyVar's bound by a type synonym and the corresponding (unsubstituted) right hand side.
1236 -- If the given 'TyCon' is not a type synonym, panics
1237 synTyConDefn :: TyCon -> ([TyVar], Type)
1238 synTyConDefn (SynTyCon {tyConTyVars = tyvars, synTcRhs = SynonymTyCon ty})
1240 synTyConDefn tycon = pprPanic "getSynTyConDefn" (ppr tycon)
1242 -- | Extract the information pertaining to the right hand side of a type synonym (@type@) declaration. Panics
1243 -- if the given 'TyCon' is not a type synonym
1244 synTyConRhs :: TyCon -> SynTyConRhs
1245 synTyConRhs (SynTyCon {synTcRhs = rhs}) = rhs
1246 synTyConRhs tc = pprPanic "synTyConRhs" (ppr tc)
1248 -- | Find the expansion of the type synonym represented by the given 'TyCon'. The free variables of this
1249 -- type will typically include those 'TyVar's bound by the 'TyCon'. Panics if the 'TyCon' is not that of
1251 synTyConType :: TyCon -> Type
1252 synTyConType tc = case synTcRhs tc of
1254 _ -> pprPanic "synTyConType" (ppr tc)
1258 -- | If the given 'TyCon' has a /single/ data constructor, i.e. it is a @data@ type with one
1259 -- alternative, a tuple type or a @newtype@ then that constructor is returned. If the 'TyCon'
1260 -- has more than one constructor, or represents a primitive or function type constructor then
1261 -- @Nothing@ is returned. In any other case, the function panics
1262 tyConSingleDataCon_maybe :: TyCon -> Maybe DataCon
1263 tyConSingleDataCon_maybe (TupleTyCon {dataCon = c}) = Just c
1264 tyConSingleDataCon_maybe (AlgTyCon {algTcRhs = DataTyCon { data_cons = [c] }}) = Just c
1265 tyConSingleDataCon_maybe (AlgTyCon {algTcRhs = NewTyCon { data_con = c }}) = Just c
1266 tyConSingleDataCon_maybe _ = Nothing
1270 -- | Is this 'TyCon' that for a class instance?
1271 isClassTyCon :: TyCon -> Bool
1272 isClassTyCon (AlgTyCon {algTcParent = ClassTyCon _}) = True
1273 isClassTyCon _ = False
1275 -- | If this 'TyCon' is that for a class instance, return the class it is for.
1276 -- Otherwise returns @Nothing@
1277 tyConClass_maybe :: TyCon -> Maybe Class
1278 tyConClass_maybe (AlgTyCon {algTcParent = ClassTyCon clas}) = Just clas
1279 tyConClass_maybe _ = Nothing
1281 ----------------------------------------------------------------------------
1282 tyConParent :: TyCon -> TyConParent
1283 tyConParent (AlgTyCon {algTcParent = parent}) = parent
1284 tyConParent (SynTyCon {synTcParent = parent}) = parent
1285 tyConParent _ = NoParentTyCon
1287 -- | Is this 'TyCon' that for a family instance, be that for a synonym or an
1288 -- algebraic family instance?
1289 isFamInstTyCon :: TyCon -> Bool
1290 isFamInstTyCon tc = case tyConParent tc of
1291 FamInstTyCon {} -> True
1294 tyConFamInstSig_maybe :: TyCon -> Maybe (TyCon, [Type], TyCon)
1295 tyConFamInstSig_maybe tc
1296 = case tyConParent tc of
1297 FamInstTyCon f ts co_tc -> Just (f, ts, co_tc)
1300 -- | If this 'TyCon' is that of a family instance, return the family in question
1301 -- and the instance types. Otherwise, return @Nothing@
1302 tyConFamInst_maybe :: TyCon -> Maybe (TyCon, [Type])
1303 tyConFamInst_maybe tc
1304 = case tyConParent tc of
1305 FamInstTyCon f ts _ -> Just (f, ts)
1308 -- | If this 'TyCon' is that of a family instance, return a 'TyCon' which represents
1309 -- a coercion identifying the representation type with the type instance family.
1310 -- Otherwise, return @Nothing@
1311 tyConFamilyCoercion_maybe :: TyCon -> Maybe TyCon
1312 tyConFamilyCoercion_maybe tc
1313 = case tyConParent tc of
1314 FamInstTyCon _ _ co -> Just co
1319 %************************************************************************
1321 \subsection[TyCon-instances]{Instance declarations for @TyCon@}
1323 %************************************************************************
1325 @TyCon@s are compared by comparing their @Unique@s.
1327 The strictness analyser needs @Ord@. It is a lexicographic order with
1328 the property @(a<=b) || (b<=a)@.
1331 instance Eq TyCon where
1332 a == b = case (a `compare` b) of { EQ -> True; _ -> False }
1333 a /= b = case (a `compare` b) of { EQ -> False; _ -> True }
1335 instance Ord TyCon where
1336 a <= b = case (a `compare` b) of { LT -> True; EQ -> True; GT -> False }
1337 a < b = case (a `compare` b) of { LT -> True; EQ -> False; GT -> False }
1338 a >= b = case (a `compare` b) of { LT -> False; EQ -> True; GT -> True }
1339 a > b = case (a `compare` b) of { LT -> False; EQ -> False; GT -> True }
1340 compare a b = getUnique a `compare` getUnique b
1342 instance Uniquable TyCon where
1343 getUnique tc = tyConUnique tc
1345 instance Outputable CoTyConDesc where
1346 ppr CoSym = ptext (sLit "SYM")
1347 ppr CoTrans = ptext (sLit "TRANS")
1348 ppr CoLeft = ptext (sLit "LEFT")
1349 ppr CoRight = ptext (sLit "RIGHT")
1350 ppr CoCsel1 = ptext (sLit "CSEL1")
1351 ppr CoCsel2 = ptext (sLit "CSEL2")
1352 ppr CoCselR = ptext (sLit "CSELR")
1353 ppr CoInst = ptext (sLit "INST")
1354 ppr CoUnsafe = ptext (sLit "UNSAFE")
1355 ppr (CoAxiom {}) = ptext (sLit "AXIOM")
1357 instance Outputable TyCon where
1358 ppr tc = ppr (getName tc)
1360 instance NamedThing TyCon where
1363 instance Data.Typeable TyCon where
1364 typeOf _ = Data.mkTyConApp (Data.mkTyCon "TyCon") []
1366 instance Data.Data TyCon where
1368 toConstr _ = abstractConstr "TyCon"
1369 gunfold _ _ = error "gunfold"
1370 dataTypeOf _ = mkNoRepType "TyCon"