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 Note [Enumeration types]
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
504 -- The 'tyConTyVars' of this 'TyCon' may mention some
505 -- of the same type variables as the classTyVars of the
506 -- parent 'Class'. E.g.
513 -- Here the 'a' is shared with the 'Class', and that is
514 -- important. In an instance declaration we expect the
515 -- two to be instantiated the same way. Eg.
518 -- instanc C [x] (Tree y) where
519 -- data T c [x] = T1 x | T2 c
522 -- | Type constructors representing an instance of a type family. Parameters:
524 -- 1) The type family in question
526 -- 2) Instance types; free variables are the 'tyConTyVars'
527 -- of the current 'TyCon' (not the family one). INVARIANT:
528 -- the number of types matches the arity of the family 'TyCon'
530 -- 3) A 'CoTyCon' identifying the representation
531 -- type with the type instance family
532 | FamInstTyCon -- See Note [Data type families]
533 -- and Note [Type synonym families]
534 TyCon -- The family TyCon
535 [Type] -- Argument types (mentions the tyConTyVars of this TyCon)
536 TyCon -- The coercion constructor
538 -- E.g. data intance T [a] = ...
539 -- gives a representation tycon:
540 -- data R:TList a = ...
541 -- axiom co a :: T [a] ~ R:TList a
542 -- with R:TList's algTcParent = FamInstTyCon T [a] co
544 -- | Checks the invariants of a 'TyConParent' given the appropriate type class name, if any
545 okParent :: Name -> TyConParent -> Bool
546 okParent _ NoParentTyCon = True
547 okParent tc_name (AssocFamilyTyCon cls) = tc_name `elem` map tyConName (classATs cls)
548 okParent tc_name (ClassTyCon cls) = tc_name == tyConName (classTyCon cls)
549 okParent _ (FamInstTyCon fam_tc tys _co_tc) = tyConArity fam_tc == length tys
551 isNoParent :: TyConParent -> Bool
552 isNoParent NoParentTyCon = True
557 -- | Information pertaining to the expansion of a type synonym (@type@)
559 = -- | An ordinary type synonyn.
561 Type -- This 'Type' is the rhs, and may mention from 'tyConTyVars'.
562 -- It acts as a template for the expansion when the 'TyCon'
563 -- is applied to some types.
565 -- | A type synonym family e.g. @type family F x y :: * -> *@
572 | CoCsel1 | CoCsel2 | CoCselR
575 | CoAxiom -- C tvs : F lhs-tys ~ rhs-ty
576 { co_ax_tvs :: [TyVar]
578 , co_ax_rhs :: Type }
583 Note [Enumeration types]
584 ~~~~~~~~~~~~~~~~~~~~~~~~
585 We define datatypes with no constructors to *not* be
586 enumerations; this fixes trac #2578, Otherwise we
587 end up generating an empty table for
588 <mod>_<type>_closure_tbl
589 which is used by tagToEnum# to map Int# to constructors
590 in an enumeration. The empty table apparently upset
593 Moreover, all the data constructor must be enumerations, meaning
594 they have type (forall abc. T a b c). GADTs are not enumerations.
600 What would [T1 ..] be? [T1,T3] :: T Int? Easiest thing is to exclude them.
603 Note [Newtype coercions]
604 ~~~~~~~~~~~~~~~~~~~~~~~~
605 The NewTyCon field nt_co is a a TyCon (a coercion constructor in fact)
606 which is used for coercing from the representation type of the
607 newtype, to the newtype itself. For example,
609 newtype T a = MkT (a -> a)
611 the NewTyCon for T will contain nt_co = CoT where CoT t : T t ~ t ->
612 t. This TyCon is a CoTyCon, so it does not have a kind on its
613 own; it basically has its own typing rule for the fully-applied
614 version. If the newtype T has k type variables then CoT has arity at
615 most k. In the case that the right hand side is a type application
616 ending with the same type variables as the left hand side, we
617 "eta-contract" the coercion. So if we had
619 newtype S a = MkT [a]
621 then we would generate the arity 0 coercion CoS : S ~ []. The
622 primary reason we do this is to make newtype deriving cleaner.
624 In the paper we'd write
625 axiom CoT : (forall t. T t) ~ (forall t. [t])
626 and then when we used CoT at a particular type, s, we'd say
628 which encodes as (TyConApp instCoercionTyCon [TyConApp CoT [], s])
630 But in GHC we instead make CoT into a new piece of type syntax, CoTyCon,
631 (like instCoercionTyCon, symCoercionTyCon etc), which must always
632 be saturated, but which encodes as
634 In the vocabulary of the paper it's as if we had axiom declarations
636 axiom CoT t : T t ~ [t]
641 newtype Parser m a = MkParser (Foogle m a)
642 Are these two types equal (to Core)?
645 Well, yes. But to see that easily we eta-reduce the RHS type of
646 Parser, in this case to ([], Froogle), so that even unsaturated applications
647 of Parser will work right. This eta reduction is done when the type
648 constructor is built, and cached in NewTyCon. The cached field is
649 only used in coreExpandTyCon_maybe.
651 Here's an example that I think showed up in practice
653 newtype T a = MkT [a]
654 newtype Foo m = MkFoo (forall a. m a -> Int)
660 w2 = MkFoo (\(MkT x) -> case w1 of MkFoo f -> f x)
662 After desugaring, and discarding the data constructors for the newtypes,
666 And now Lint complains unless Foo T == Foo [], and that requires T==[]
668 This point carries over to the newtype coercion, because we need to
670 w2 = w1 `cast` Foo CoT
672 so the coercion tycon CoT must have
677 %************************************************************************
681 %************************************************************************
683 A PrimRep is somewhat similar to a CgRep (see codeGen/SMRep) and a
684 MachRep (see cmm/CmmExpr), although each of these types has a distinct
685 and clearly defined purpose:
687 - A PrimRep is a CgRep + information about signedness + information
688 about primitive pointers (AddrRep). Signedness and primitive
689 pointers are required when passing a primitive type to a foreign
690 function, but aren't needed for call/return conventions of Haskell
693 - A MachRep is a basic machine type (non-void, doesn't contain
694 information on pointerhood or signedness, but contains some
695 reps that don't have corresponding Haskell types).
698 -- | A 'PrimRep' is an abstraction of a type. It contains information that
699 -- the code generator needs in order to pass arguments, return results,
700 -- and store values of this type.
704 | IntRep -- ^ Signed, word-sized value
705 | WordRep -- ^ Unsigned, word-sized value
706 | Int64Rep -- ^ Signed, 64 bit value (with 32-bit words only)
707 | Word64Rep -- ^ Unsigned, 64 bit value (with 32-bit words only)
708 | AddrRep -- ^ A pointer, but /not/ to a Haskell value (use 'PtrRep')
713 instance Outputable PrimRep where
714 ppr r = text (show r)
716 -- | Find the size of a 'PrimRep', in words
717 primRepSizeW :: PrimRep -> Int
718 primRepSizeW IntRep = 1
719 primRepSizeW WordRep = 1
720 primRepSizeW Int64Rep = wORD64_SIZE `quot` wORD_SIZE
721 primRepSizeW Word64Rep= wORD64_SIZE `quot` wORD_SIZE
722 primRepSizeW FloatRep = 1 -- NB. might not take a full word
723 primRepSizeW DoubleRep= dOUBLE_SIZE `quot` wORD_SIZE
724 primRepSizeW AddrRep = 1
725 primRepSizeW PtrRep = 1
726 primRepSizeW VoidRep = 0
729 %************************************************************************
731 \subsection{TyCon Construction}
733 %************************************************************************
735 Note: the TyCon constructors all take a Kind as one argument, even though
736 they could, in principle, work out their Kind from their other arguments.
737 But to do so they need functions from Types, and that makes a nasty
738 module mutual-recursion. And they aren't called from many places.
739 So we compromise, and move their Kind calculation to the call site.
742 -- | Given the name of the function type constructor and it's kind, create the
743 -- corresponding 'TyCon'. It is reccomended to use 'TypeRep.funTyCon' if you want
744 -- this functionality
745 mkFunTyCon :: Name -> Kind -> TyCon
748 tyConUnique = nameUnique name,
754 -- | This is the making of an algebraic 'TyCon'. Notably, you have to
755 -- pass in the generic (in the -XGenerics sense) information about the
756 -- type constructor - you can get hold of it easily (see Generics
759 -> Kind -- ^ Kind of the resulting 'TyCon'
760 -> [TyVar] -- ^ 'TyVar's scoped over: see 'tyConTyVars'.
761 -- Arity is inferred from the length of this list
762 -> [PredType] -- ^ Stupid theta: see 'algTcStupidTheta'
763 -> AlgTyConRhs -- ^ Information about dat aconstructors
765 -> RecFlag -- ^ Is the 'TyCon' recursive?
766 -> Bool -- ^ Does it have generic functions? See 'hasGenerics'
767 -> Bool -- ^ Was the 'TyCon' declared with GADT syntax?
769 mkAlgTyCon name kind tyvars stupid rhs parent is_rec gen_info gadt_syn
772 tyConUnique = nameUnique name,
774 tyConArity = length tyvars,
775 tyConTyVars = tyvars,
776 algTcStupidTheta = stupid,
778 algTcParent = ASSERT( okParent name parent ) parent,
780 algTcGadtSyntax = gadt_syn,
781 hasGenerics = gen_info
784 -- | Simpler specialization of 'mkAlgTyCon' for classes
785 mkClassTyCon :: Name -> Kind -> [TyVar] -> AlgTyConRhs -> Class -> RecFlag -> TyCon
786 mkClassTyCon name kind tyvars rhs clas is_rec =
787 mkAlgTyCon name kind tyvars [] rhs (ClassTyCon clas) is_rec False False
790 -> Kind -- ^ Kind of the resulting 'TyCon'
791 -> Arity -- ^ Arity of the tuple
792 -> [TyVar] -- ^ 'TyVar's scoped over: see 'tyConTyVars'
794 -> Boxity -- ^ Whether the tuple is boxed or unboxed
795 -> Bool -- ^ Does it have generic functions? See 'hasGenerics'
797 mkTupleTyCon name kind arity tyvars con boxed gen_info
799 tyConUnique = nameUnique name,
804 tyConTyVars = tyvars,
806 hasGenerics = gen_info
809 -- ^ Foreign-imported (.NET) type constructors are represented
810 -- as primitive, but /lifted/, 'TyCons' for now. They are lifted
811 -- because the Haskell type @T@ representing the (foreign) .NET
812 -- type @T@ is actually implemented (in ILX) as a @thunk<T>@
813 mkForeignTyCon :: Name
814 -> Maybe FastString -- ^ Name of the foreign imported thing, maybe
818 mkForeignTyCon name ext_name kind arity
821 tyConUnique = nameUnique name,
824 primTyConRep = PtrRep, -- they all do
826 tyConExtName = ext_name
830 -- | Create an unlifted primitive 'TyCon', such as @Int#@
831 mkPrimTyCon :: Name -> Kind -> Arity -> PrimRep -> TyCon
832 mkPrimTyCon name kind arity rep
833 = mkPrimTyCon' name kind arity rep True
835 -- | Kind constructors
836 mkKindTyCon :: Name -> Kind -> TyCon
837 mkKindTyCon name kind
838 = mkPrimTyCon' name kind 0 VoidRep True
840 -- | Create a lifted primitive 'TyCon' such as @RealWorld@
841 mkLiftedPrimTyCon :: Name -> Kind -> Arity -> PrimRep -> TyCon
842 mkLiftedPrimTyCon name kind arity rep
843 = mkPrimTyCon' name kind arity rep False
845 mkPrimTyCon' :: Name -> Kind -> Arity -> PrimRep -> Bool -> TyCon
846 mkPrimTyCon' name kind arity rep is_unlifted
849 tyConUnique = nameUnique name,
853 isUnLifted = is_unlifted,
854 tyConExtName = Nothing
857 -- | Create a type synonym 'TyCon'
858 mkSynTyCon :: Name -> Kind -> [TyVar] -> SynTyConRhs -> TyConParent -> TyCon
859 mkSynTyCon name kind tyvars rhs parent
862 tyConUnique = nameUnique name,
864 tyConArity = length tyvars,
865 tyConTyVars = tyvars,
870 -- | Create a coercion 'TyCon'
871 mkCoercionTyCon :: Name -> Arity
874 mkCoercionTyCon name arity desc
877 tyConUnique = nameUnique name,
881 mkAnyTyCon :: Name -> Kind -> TyCon
883 = AnyTyCon { tyConName = name,
885 tyConUnique = nameUnique name }
887 -- | Create a super-kind 'TyCon'
888 mkSuperKindTyCon :: Name -> TyCon -- Super kinds always have arity zero
889 mkSuperKindTyCon name
892 tyConUnique = nameUnique name
897 isFunTyCon :: TyCon -> Bool
898 isFunTyCon (FunTyCon {}) = True
901 -- | Test if the 'TyCon' is algebraic but abstract (invisible data constructors)
902 isAbstractTyCon :: TyCon -> Bool
903 isAbstractTyCon (AlgTyCon { algTcRhs = AbstractTyCon }) = True
904 isAbstractTyCon _ = False
906 -- | Make an algebraic 'TyCon' abstract. Panics if the supplied 'TyCon' is not algebraic
907 makeTyConAbstract :: TyCon -> TyCon
908 makeTyConAbstract tc@(AlgTyCon {}) = tc { algTcRhs = AbstractTyCon }
909 makeTyConAbstract tc = pprPanic "makeTyConAbstract" (ppr tc)
911 -- | Does this 'TyCon' represent something that cannot be defined in Haskell?
912 isPrimTyCon :: TyCon -> Bool
913 isPrimTyCon (PrimTyCon {}) = True
914 isPrimTyCon _ = False
916 -- | Is this 'TyCon' unlifted (i.e. cannot contain bottom)? Note that this can only
917 -- be true for primitive and unboxed-tuple 'TyCon's
918 isUnLiftedTyCon :: TyCon -> Bool
919 isUnLiftedTyCon (PrimTyCon {isUnLifted = is_unlifted}) = is_unlifted
920 isUnLiftedTyCon (TupleTyCon {tyConBoxed = boxity}) = not (isBoxed boxity)
921 isUnLiftedTyCon _ = False
923 -- | Returns @True@ if the supplied 'TyCon' resulted from either a
924 -- @data@ or @newtype@ declaration
925 isAlgTyCon :: TyCon -> Bool
926 isAlgTyCon (AlgTyCon {}) = True
927 isAlgTyCon (TupleTyCon {}) = True
930 isDataTyCon :: TyCon -> Bool
931 -- ^ Returns @True@ for data types that are /definitely/ represented by
932 -- heap-allocated constructors. These are scrutinised by Core-level
933 -- @case@ expressions, and they get info tables allocated for them.
935 -- Generally, the function will be true for all @data@ types and false
936 -- for @newtype@s, unboxed tuples and type family 'TyCon's. But it is
937 -- not guarenteed to return @True@ in all cases that it could.
939 -- NB: for a data type family, only the /instance/ 'TyCon's
940 -- get an info table. The family declaration 'TyCon' does not
941 isDataTyCon (AlgTyCon {algTcRhs = rhs})
943 DataFamilyTyCon {} -> False
946 AbstractTyCon -> False -- We don't know, so return False
947 isDataTyCon (TupleTyCon {tyConBoxed = boxity}) = isBoxed boxity
948 isDataTyCon _ = False
950 -- | Is this 'TyCon' that for a @newtype@
951 isNewTyCon :: TyCon -> Bool
952 isNewTyCon (AlgTyCon {algTcRhs = NewTyCon {}}) = True
955 -- | Take a 'TyCon' apart into the 'TyVar's it scopes over, the 'Type' it expands
956 -- into, and (possibly) a coercion from the representation type to the @newtype@.
957 -- Returns @Nothing@ if this is not possible.
958 unwrapNewTyCon_maybe :: TyCon -> Maybe ([TyVar], Type, Maybe TyCon)
959 unwrapNewTyCon_maybe (AlgTyCon { tyConTyVars = tvs,
960 algTcRhs = NewTyCon { nt_co = mb_co,
962 = Just (tvs, rhs, mb_co)
963 unwrapNewTyCon_maybe _ = Nothing
965 isProductTyCon :: TyCon -> Bool
966 -- | A /product/ 'TyCon' must both:
968 -- 1. Have /one/ constructor
970 -- 2. /Not/ be existential
972 -- However other than this there are few restrictions: they may be @data@ or @newtype@
973 -- 'TyCon's of any boxity and may even be recursive.
974 isProductTyCon tc@(AlgTyCon {}) = case algTcRhs tc of
975 DataTyCon{ data_cons = [data_con] }
976 -> isVanillaDataCon data_con
979 isProductTyCon (TupleTyCon {}) = True
980 isProductTyCon _ = False
982 -- | Is this a 'TyCon' representing a type synonym (@type@)?
983 isSynTyCon :: TyCon -> Bool
984 isSynTyCon (SynTyCon {}) = True
987 -- As for newtypes, it is in some contexts important to distinguish between
988 -- closed synonyms and synonym families, as synonym families have no unique
989 -- right hand side to which a synonym family application can expand.
992 isDecomposableTyCon :: TyCon -> Bool
993 -- True iff we can decompose (T a b c) into ((T a b) c)
994 -- Specifically NOT true of synonyms (open and otherwise) and coercions
995 isDecomposableTyCon (SynTyCon {}) = False
996 isDecomposableTyCon (CoTyCon {}) = False
997 isDecomposableTyCon _other = True
999 -- | Is this an algebraic 'TyCon' declared with the GADT syntax?
1000 isGadtSyntaxTyCon :: TyCon -> Bool
1001 isGadtSyntaxTyCon (AlgTyCon { algTcGadtSyntax = res }) = res
1002 isGadtSyntaxTyCon _ = False
1004 -- | Is this an algebraic 'TyCon' which is just an enumeration of values?
1005 isEnumerationTyCon :: TyCon -> Bool
1006 -- See Note [Enumeration types] in TyCon
1007 isEnumerationTyCon (AlgTyCon {algTcRhs = DataTyCon { is_enum = res }}) = res
1008 isEnumerationTyCon (TupleTyCon {tyConArity = arity}) = arity == 0
1009 isEnumerationTyCon _ = False
1011 -- | Is this a 'TyCon', synonym or otherwise, that may have further instances appear?
1012 isFamilyTyCon :: TyCon -> Bool
1013 isFamilyTyCon (SynTyCon {synTcRhs = SynFamilyTyCon {}}) = True
1014 isFamilyTyCon (AlgTyCon {algTcRhs = DataFamilyTyCon {}}) = True
1015 isFamilyTyCon _ = False
1017 -- | Is this a synonym 'TyCon' that can have may have further instances appear?
1018 isSynFamilyTyCon :: TyCon -> Bool
1019 isSynFamilyTyCon (SynTyCon {synTcRhs = SynFamilyTyCon {}}) = True
1020 isSynFamilyTyCon _ = False
1022 -- | Is this a synonym 'TyCon' that can have may have further instances appear?
1023 isDataFamilyTyCon :: TyCon -> Bool
1024 isDataFamilyTyCon (AlgTyCon {algTcRhs = DataFamilyTyCon {}}) = True
1025 isDataFamilyTyCon _ = False
1027 -- | Is this a synonym 'TyCon' that can have no further instances appear?
1028 isClosedSynTyCon :: TyCon -> Bool
1029 isClosedSynTyCon tycon = isSynTyCon tycon && not (isFamilyTyCon tycon)
1031 -- | Injective 'TyCon's can be decomposed, so that
1032 -- T ty1 ~ T ty2 => ty1 ~ ty2
1033 isInjectiveTyCon :: TyCon -> Bool
1034 isInjectiveTyCon tc = not (isSynTyCon tc)
1035 -- Ultimately we may have injective associated types
1036 -- in which case this test will become more interesting
1038 -- It'd be unusual to call isInjectiveTyCon on a regular H98
1039 -- type synonym, because you should probably have expanded it first
1040 -- But regardless, it's not injective!
1042 -- | Are we able to extract informationa 'TyVar' to class argument list
1043 -- mappping from a given 'TyCon'?
1044 isTyConAssoc :: TyCon -> Bool
1045 isTyConAssoc tc = case tyConParent tc of
1046 AssocFamilyTyCon {} -> True
1049 -- The unit tycon didn't used to be classed as a tuple tycon
1050 -- but I thought that was silly so I've undone it
1051 -- If it can't be for some reason, it should be a AlgTyCon
1052 isTupleTyCon :: TyCon -> Bool
1053 -- ^ Does this 'TyCon' represent a tuple?
1055 -- NB: when compiling @Data.Tuple@, the tycons won't reply @True@ to
1056 -- 'isTupleTyCon', becuase they are built as 'AlgTyCons'. However they
1057 -- get spat into the interface file as tuple tycons, so I don't think
1059 isTupleTyCon (TupleTyCon {}) = True
1060 isTupleTyCon _ = False
1062 -- | Is this the 'TyCon' for an unboxed tuple?
1063 isUnboxedTupleTyCon :: TyCon -> Bool
1064 isUnboxedTupleTyCon (TupleTyCon {tyConBoxed = boxity}) = not (isBoxed boxity)
1065 isUnboxedTupleTyCon _ = False
1067 -- | Is this the 'TyCon' for a boxed tuple?
1068 isBoxedTupleTyCon :: TyCon -> Bool
1069 isBoxedTupleTyCon (TupleTyCon {tyConBoxed = boxity}) = isBoxed boxity
1070 isBoxedTupleTyCon _ = False
1072 -- | Extract the boxity of the given 'TyCon', if it is a 'TupleTyCon'.
1074 tupleTyConBoxity :: TyCon -> Boxity
1075 tupleTyConBoxity tc = tyConBoxed tc
1077 -- | Is this a recursive 'TyCon'?
1078 isRecursiveTyCon :: TyCon -> Bool
1079 isRecursiveTyCon (AlgTyCon {algTcRec = Recursive}) = True
1080 isRecursiveTyCon _ = False
1082 -- | Did this 'TyCon' originate from type-checking a .h*-boot file?
1083 isHiBootTyCon :: TyCon -> Bool
1084 -- Used for knot-tying in hi-boot files
1085 isHiBootTyCon (AlgTyCon {algTcRhs = AbstractTyCon}) = True
1086 isHiBootTyCon _ = False
1088 -- | Is this the 'TyCon' of a foreign-imported type constructor?
1089 isForeignTyCon :: TyCon -> Bool
1090 isForeignTyCon (PrimTyCon {tyConExtName = Just _}) = True
1091 isForeignTyCon _ = False
1093 -- | Is this a super-kind 'TyCon'?
1094 isSuperKindTyCon :: TyCon -> Bool
1095 isSuperKindTyCon (SuperKindTyCon {}) = True
1096 isSuperKindTyCon _ = False
1098 -- | Is this an AnyTyCon?
1099 isAnyTyCon :: TyCon -> Bool
1100 isAnyTyCon (AnyTyCon {}) = True
1101 isAnyTyCon _ = False
1103 -- | Attempt to pull a 'TyCon' apart into the arity and 'coKindFun' of
1104 -- a coercion 'TyCon'. Returns @Nothing@ if the 'TyCon' is not of the
1106 isCoercionTyCon_maybe :: TyCon -> Maybe (Arity, CoTyConDesc)
1107 isCoercionTyCon_maybe (CoTyCon {tyConArity = ar, coTcDesc = desc})
1109 isCoercionTyCon_maybe _ = Nothing
1111 -- | Is this a 'TyCon' that represents a coercion?
1112 isCoercionTyCon :: TyCon -> Bool
1113 isCoercionTyCon (CoTyCon {}) = True
1114 isCoercionTyCon _ = False
1116 -- | Identifies implicit tycons that, in particular, do not go into interface
1117 -- files (because they are implicitly reconstructed when the interface is
1122 -- * Associated families are implicit, as they are re-constructed from
1123 -- the class declaration in which they reside, and
1125 -- * Family instances are /not/ implicit as they represent the instance body
1126 -- (similar to a @dfun@ does that for a class instance).
1127 isImplicitTyCon :: TyCon -> Bool
1128 isImplicitTyCon tycon | isTyConAssoc tycon = True
1129 | isSynTyCon tycon = False
1130 | isAlgTyCon tycon = isClassTyCon tycon ||
1132 isImplicitTyCon _other = True
1133 -- catches: FunTyCon, PrimTyCon,
1134 -- CoTyCon, SuperKindTyCon
1138 -----------------------------------------------
1139 -- Expand type-constructor applications
1140 -----------------------------------------------
1143 tcExpandTyCon_maybe, coreExpandTyCon_maybe
1145 -> [Type] -- ^ Arguments to 'TyCon'
1146 -> Maybe ([(TyVar,Type)],
1148 [Type]) -- ^ Returns a 'TyVar' substitution, the body type
1149 -- of the synonym (not yet substituted) and any arguments
1150 -- remaining from the application
1152 -- ^ Used to create the view the /typechecker/ has on 'TyCon's. We expand (closed) synonyms only, cf. 'coreExpandTyCon_maybe'
1153 tcExpandTyCon_maybe (SynTyCon {tyConTyVars = tvs,
1154 synTcRhs = SynonymTyCon rhs }) tys
1155 = expand tvs rhs tys
1156 tcExpandTyCon_maybe _ _ = Nothing
1160 -- ^ Used to create the view /Core/ has on 'TyCon's. We expand not only closed synonyms like 'tcExpandTyCon_maybe',
1161 -- but also non-recursive @newtype@s
1162 coreExpandTyCon_maybe (AlgTyCon {
1163 algTcRhs = NewTyCon { nt_etad_rhs = etad_rhs, nt_co = Nothing }}) tys
1164 = case etad_rhs of -- Don't do this in the pattern match, lest we accidentally
1165 -- match the etad_rhs of a *recursive* newtype
1166 (tvs,rhs) -> expand tvs rhs tys
1168 coreExpandTyCon_maybe tycon tys = tcExpandTyCon_maybe tycon tys
1172 expand :: [TyVar] -> Type -- Template
1174 -> Maybe ([(TyVar,Type)], Type, [Type]) -- Expansion
1176 = case n_tvs `compare` length tys of
1177 LT -> Just (tvs `zip` tys, rhs, drop n_tvs tys)
1178 EQ -> Just (tvs `zip` tys, rhs, [])
1185 -- | Does this 'TyCon' have any generic to\/from functions available? See also 'hasGenerics'
1186 tyConHasGenerics :: TyCon -> Bool
1187 tyConHasGenerics (AlgTyCon {hasGenerics = hg}) = hg
1188 tyConHasGenerics (TupleTyCon {hasGenerics = hg}) = hg
1189 tyConHasGenerics _ = False -- Synonyms
1191 tyConKind :: TyCon -> Kind
1192 tyConKind (FunTyCon { tc_kind = k }) = k
1193 tyConKind (AlgTyCon { tc_kind = k }) = k
1194 tyConKind (TupleTyCon { tc_kind = k }) = k
1195 tyConKind (SynTyCon { tc_kind = k }) = k
1196 tyConKind (PrimTyCon { tc_kind = k }) = k
1197 tyConKind (AnyTyCon { tc_kind = k }) = k
1198 tyConKind tc = pprPanic "tyConKind" (ppr tc) -- SuperKindTyCon and CoTyCon
1200 tyConHasKind :: TyCon -> Bool
1201 tyConHasKind (SuperKindTyCon {}) = False
1202 tyConHasKind (CoTyCon {}) = False
1203 tyConHasKind _ = True
1205 -- | As 'tyConDataCons_maybe', but returns the empty list of constructors if no constructors
1207 tyConDataCons :: TyCon -> [DataCon]
1208 -- It's convenient for tyConDataCons to return the
1209 -- empty list for type synonyms etc
1210 tyConDataCons tycon = tyConDataCons_maybe tycon `orElse` []
1212 -- | Determine the 'DataCon's originating from the given 'TyCon', if the 'TyCon' is the
1213 -- sort that can have any constructors (note: this does not include abstract algebraic types)
1214 tyConDataCons_maybe :: TyCon -> Maybe [DataCon]
1215 tyConDataCons_maybe (AlgTyCon {algTcRhs = DataTyCon { data_cons = cons }}) = Just cons
1216 tyConDataCons_maybe (AlgTyCon {algTcRhs = NewTyCon { data_con = con }}) = Just [con]
1217 tyConDataCons_maybe (TupleTyCon {dataCon = con}) = Just [con]
1218 tyConDataCons_maybe _ = Nothing
1220 -- | Determine the number of value constructors a 'TyCon' has. Panics if the 'TyCon'
1221 -- is not algebraic or a tuple
1222 tyConFamilySize :: TyCon -> Int
1223 tyConFamilySize (AlgTyCon {algTcRhs = DataTyCon {data_cons = cons}}) =
1225 tyConFamilySize (AlgTyCon {algTcRhs = NewTyCon {}}) = 1
1226 tyConFamilySize (AlgTyCon {algTcRhs = DataFamilyTyCon {}}) = 0
1227 tyConFamilySize (TupleTyCon {}) = 1
1228 tyConFamilySize other = pprPanic "tyConFamilySize:" (ppr other)
1230 -- | Extract an 'AlgTyConRhs' with information about data constructors from an algebraic or tuple
1231 -- 'TyCon'. Panics for any other sort of 'TyCon'
1232 algTyConRhs :: TyCon -> AlgTyConRhs
1233 algTyConRhs (AlgTyCon {algTcRhs = rhs}) = rhs
1234 algTyConRhs (TupleTyCon {dataCon = con, tyConArity = arity})
1235 = DataTyCon { data_cons = [con], is_enum = arity == 0 }
1236 algTyConRhs other = pprPanic "algTyConRhs" (ppr other)
1240 -- | Extract the bound type variables and type expansion of a type synonym 'TyCon'. Panics if the
1241 -- 'TyCon' is not a synonym
1242 newTyConRhs :: TyCon -> ([TyVar], Type)
1243 newTyConRhs (AlgTyCon {tyConTyVars = tvs, algTcRhs = NewTyCon { nt_rhs = rhs }}) = (tvs, rhs)
1244 newTyConRhs tycon = pprPanic "newTyConRhs" (ppr tycon)
1246 -- | Extract the bound type variables and type expansion of an eta-contracted type synonym 'TyCon'.
1247 -- Panics if the 'TyCon' is not a synonym
1248 newTyConEtadRhs :: TyCon -> ([TyVar], Type)
1249 newTyConEtadRhs (AlgTyCon {algTcRhs = NewTyCon { nt_etad_rhs = tvs_rhs }}) = tvs_rhs
1250 newTyConEtadRhs tycon = pprPanic "newTyConEtadRhs" (ppr tycon)
1252 -- | Extracts the @newtype@ coercion from such a 'TyCon', which can be used to construct something
1253 -- with the @newtype@s type from its representation type (right hand side). If the supplied 'TyCon'
1254 -- is not a @newtype@, returns @Nothing@
1255 newTyConCo_maybe :: TyCon -> Maybe TyCon
1256 newTyConCo_maybe (AlgTyCon {algTcRhs = NewTyCon { nt_co = co }}) = co
1257 newTyConCo_maybe _ = Nothing
1259 -- | Find the primitive representation of a 'TyCon'
1260 tyConPrimRep :: TyCon -> PrimRep
1261 tyConPrimRep (PrimTyCon {primTyConRep = rep}) = rep
1262 tyConPrimRep tc = ASSERT(not (isUnboxedTupleTyCon tc)) PtrRep
1266 -- | Find the \"stupid theta\" of the 'TyCon'. A \"stupid theta\" is the context to the left of
1267 -- an algebraic type declaration, e.g. @Eq a@ in the declaration @data Eq a => T a ...@
1268 tyConStupidTheta :: TyCon -> [PredType]
1269 tyConStupidTheta (AlgTyCon {algTcStupidTheta = stupid}) = stupid
1270 tyConStupidTheta (TupleTyCon {}) = []
1271 tyConStupidTheta tycon = pprPanic "tyConStupidTheta" (ppr tycon)
1275 -- | Extract the 'TyVar's bound by a type synonym and the corresponding (unsubstituted) right hand side.
1276 -- If the given 'TyCon' is not a type synonym, panics
1277 synTyConDefn :: TyCon -> ([TyVar], Type)
1278 synTyConDefn (SynTyCon {tyConTyVars = tyvars, synTcRhs = SynonymTyCon ty})
1280 synTyConDefn tycon = pprPanic "getSynTyConDefn" (ppr tycon)
1282 -- | Extract the information pertaining to the right hand side of a type synonym (@type@) declaration. Panics
1283 -- if the given 'TyCon' is not a type synonym
1284 synTyConRhs :: TyCon -> SynTyConRhs
1285 synTyConRhs (SynTyCon {synTcRhs = rhs}) = rhs
1286 synTyConRhs tc = pprPanic "synTyConRhs" (ppr tc)
1288 -- | Find the expansion of the type synonym represented by the given 'TyCon'. The free variables of this
1289 -- type will typically include those 'TyVar's bound by the 'TyCon'. Panics if the 'TyCon' is not that of
1291 synTyConType :: TyCon -> Type
1292 synTyConType tc = case synTcRhs tc of
1294 _ -> pprPanic "synTyConType" (ppr tc)
1298 -- | If the given 'TyCon' has a /single/ data constructor, i.e. it is a @data@ type with one
1299 -- alternative, a tuple type or a @newtype@ then that constructor is returned. If the 'TyCon'
1300 -- has more than one constructor, or represents a primitive or function type constructor then
1301 -- @Nothing@ is returned. In any other case, the function panics
1302 tyConSingleDataCon_maybe :: TyCon -> Maybe DataCon
1303 tyConSingleDataCon_maybe (TupleTyCon {dataCon = c}) = Just c
1304 tyConSingleDataCon_maybe (AlgTyCon {algTcRhs = DataTyCon { data_cons = [c] }}) = Just c
1305 tyConSingleDataCon_maybe (AlgTyCon {algTcRhs = NewTyCon { data_con = c }}) = Just c
1306 tyConSingleDataCon_maybe _ = Nothing
1310 -- | Is this 'TyCon' that for a class instance?
1311 isClassTyCon :: TyCon -> Bool
1312 isClassTyCon (AlgTyCon {algTcParent = ClassTyCon _}) = True
1313 isClassTyCon _ = False
1315 -- | If this 'TyCon' is that for a class instance, return the class it is for.
1316 -- Otherwise returns @Nothing@
1317 tyConClass_maybe :: TyCon -> Maybe Class
1318 tyConClass_maybe (AlgTyCon {algTcParent = ClassTyCon clas}) = Just clas
1319 tyConClass_maybe _ = Nothing
1321 ----------------------------------------------------------------------------
1322 tyConParent :: TyCon -> TyConParent
1323 tyConParent (AlgTyCon {algTcParent = parent}) = parent
1324 tyConParent (SynTyCon {synTcParent = parent}) = parent
1325 tyConParent _ = NoParentTyCon
1327 -- | Is this 'TyCon' that for a family instance, be that for a synonym or an
1328 -- algebraic family instance?
1329 isFamInstTyCon :: TyCon -> Bool
1330 isFamInstTyCon tc = case tyConParent tc of
1331 FamInstTyCon {} -> True
1334 tyConFamInstSig_maybe :: TyCon -> Maybe (TyCon, [Type], TyCon)
1335 tyConFamInstSig_maybe tc
1336 = case tyConParent tc of
1337 FamInstTyCon f ts co_tc -> Just (f, ts, co_tc)
1340 -- | If this 'TyCon' is that of a family instance, return the family in question
1341 -- and the instance types. Otherwise, return @Nothing@
1342 tyConFamInst_maybe :: TyCon -> Maybe (TyCon, [Type])
1343 tyConFamInst_maybe tc
1344 = case tyConParent tc of
1345 FamInstTyCon f ts _ -> Just (f, ts)
1348 -- | If this 'TyCon' is that of a family instance, return a 'TyCon' which represents
1349 -- a coercion identifying the representation type with the type instance family.
1350 -- Otherwise, return @Nothing@
1351 tyConFamilyCoercion_maybe :: TyCon -> Maybe TyCon
1352 tyConFamilyCoercion_maybe tc
1353 = case tyConParent tc of
1354 FamInstTyCon _ _ co -> Just co
1359 %************************************************************************
1361 \subsection[TyCon-instances]{Instance declarations for @TyCon@}
1363 %************************************************************************
1365 @TyCon@s are compared by comparing their @Unique@s.
1367 The strictness analyser needs @Ord@. It is a lexicographic order with
1368 the property @(a<=b) || (b<=a)@.
1371 instance Eq TyCon where
1372 a == b = case (a `compare` b) of { EQ -> True; _ -> False }
1373 a /= b = case (a `compare` b) of { EQ -> False; _ -> True }
1375 instance Ord TyCon where
1376 a <= b = case (a `compare` b) of { LT -> True; EQ -> True; GT -> False }
1377 a < b = case (a `compare` b) of { LT -> True; EQ -> False; GT -> False }
1378 a >= b = case (a `compare` b) of { LT -> False; EQ -> True; GT -> True }
1379 a > b = case (a `compare` b) of { LT -> False; EQ -> False; GT -> True }
1380 compare a b = getUnique a `compare` getUnique b
1382 instance Uniquable TyCon where
1383 getUnique tc = tyConUnique tc
1385 instance Outputable CoTyConDesc where
1386 ppr CoSym = ptext (sLit "SYM")
1387 ppr CoTrans = ptext (sLit "TRANS")
1388 ppr CoLeft = ptext (sLit "LEFT")
1389 ppr CoRight = ptext (sLit "RIGHT")
1390 ppr CoCsel1 = ptext (sLit "CSEL1")
1391 ppr CoCsel2 = ptext (sLit "CSEL2")
1392 ppr CoCselR = ptext (sLit "CSELR")
1393 ppr CoInst = ptext (sLit "INST")
1394 ppr CoUnsafe = ptext (sLit "UNSAFE")
1395 ppr (CoAxiom {}) = ptext (sLit "AXIOM")
1397 instance Outputable TyCon where
1398 ppr tc = ppr (getName tc)
1400 instance NamedThing TyCon where
1403 instance Data.Typeable TyCon where
1404 typeOf _ = Data.mkTyConApp (Data.mkTyCon "TyCon") []
1406 instance Data.Data TyCon where
1408 toConstr _ = abstractConstr "TyCon"
1409 gunfold _ _ = error "gunfold"
1410 dataTypeOf _ = mkNoRepType "TyCon"