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,
17 -- ** Coercion axiom constructors
18 CoAxiom(..), coAxiomName, coAxiomArity,
20 -- ** Constructing TyCons
33 -- ** Predicates on TyCons
35 isClassTyCon, isFamInstTyCon,
38 isTupleTyCon, isUnboxedTupleTyCon, isBoxedTupleTyCon,
39 isSynTyCon, isClosedSynTyCon,
40 isSuperKindTyCon, isDecomposableTyCon,
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,
75 newTyConCo, newTyConCo_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
132 translates to a "representation TyCon", 'R:FList', where
133 R:FList is a SynTyCon, whose
134 SynTyConRhs is (SynonymTyCon (Maybe a))
135 TyConParent is (FamInstTyCon F [a] co)
136 where co :: F [a] ~ R:FList a
138 It's very much as if the user had written
139 type instance F [a] = R:FList a
140 type R:FList a = Maybe a
141 Indeed, in GHC's internal representation, the RHS of every
142 'type instance' is simply an application of the representation
143 TyCon to the quantified varaibles.
145 The intermediate representation TyCon is a bit gratuitous, but
148 each 'type instance' decls is in 1-1 correspondance
149 with its representation TyCon
151 So the result of typechecking a 'type instance' decl is just a
152 TyCon. In turn this means that type and data families can be
155 * Translation of type family decl:
158 a SynTyCon 'F', whose SynTyConRhs is SynFamilyTyCon
160 * Translation of type instance decl:
161 type instance F [a] = Maybe a
163 A SynTyCon 'R:FList a', whose
164 SynTyConRhs is (SynonymTyCon (Maybe a))
165 TyConParent is (FamInstTyCon F [a] co)
166 where co :: F [a] ~ R:FList a
167 Notice that we introduce a gratuitous vanilla type synonym
168 type R:FList a = Maybe a
169 solely so that type and data families can be treated more
170 uniformly, via a single FamInstTyCon descriptor
172 * In the future we might want to support
173 * closed type families (esp when we have proper kinds)
174 * injective type families (allow decomposition)
175 but we don't at the moment [2010]
177 Note [Data type families]
178 ~~~~~~~~~~~~~~~~~~~~~~~~~
179 See also Note [Wrappers for data instance tycons] in MkId.lhs
181 * Data type families are declared thus
183 data instance T Int = T1 | T2 Bool
185 Here T is the "family TyCon".
187 * Reply "yes" to isDataFamilyTyCon, and isFamilyTyCon
189 * Reply "yes" to isDataFamilyTyCon, and isFamilyTyCon
191 * The user does not see any "equivalent types" as he did with type
192 synonym families. He just sees constructors with types
196 * Here's the FC version of the above declarations:
199 data R:TInt = T1 | T2 Bool
200 axiom ax_ti : T Int ~ R:TInt
202 The R:TInt is the "representation TyCons".
203 It has an AlgTyConParent of
204 FamInstTyCon T [Int] ax_ti
206 * The data contructor T2 has a wrapper (which is what the
207 source-level "T2" invokes):
209 $WT2 :: Bool -> T Int
210 $WT2 b = T2 b `cast` sym ax_ti
212 * A data instance can declare a fully-fledged GADT:
214 data instance T (a,b) where
216 X2 :: a -> b -> T (a,b)
218 Here's the FC version of the above declaration:
221 X1 :: R:TPair Int Bool
222 X2 :: a -> b -> R:TPair a b
223 axiom ax_pr :: T (a,b) ~ R:TPair a b
225 $WX1 :: forall a b. a -> b -> T (a,b)
226 $WX1 a b (x::a) (y::b) = X2 a b x y `cast` sym (ax_pr a b)
228 The R:TPair are the "representation TyCons".
229 We have a bit of work to do, to unpick the result types of the
230 data instance declaration for T (a,b), to get the result type in the
231 representation; e.g. T (a,b) --> R:TPair a b
233 The representation TyCon R:TList, has an AlgTyConParent of
235 FamInstTyCon T [(a,b)] ax_pr
237 * Notice that T is NOT translated to a FC type function; it just
238 becomes a "data type" with no constructors, which can be coerced inot
239 into R:TInt, R:TPair by the axioms. These axioms
240 axioms come into play when (and *only* when) you
241 - use a data constructor
242 - do pattern matching
243 Rather like newtype, in fact
247 - T behaves just like a data type so far as decomposition is concerned
249 - (T Int) is not implicitly converted to R:TInt during type inference.
250 Indeed the latter type is unknown to the programmer.
252 - There *is* an instance for (T Int) in the type-family instance
253 environment, but it is only used for overlap checking
255 - It's fine to have T in the LHS of a type function:
256 type instance F (T a) = [a]
258 It was this last point that confused me! The big thing is that you
259 should not think of a data family T as a *type function* at all, not
260 even an injective one! We can't allow even injective type functions
261 on the LHS of a type function:
262 type family injective G a :: *
263 type instance F (G Int) = Bool
264 is no good, even if G is injective, because consider
265 type instance G Int = Bool
266 type instance F Bool = Char
268 So a data type family is not an injective type function. It's just a
269 data type with some axioms that connect it to other data types.
271 %************************************************************************
273 \subsection{The data type}
275 %************************************************************************
278 -- | TyCons represent type constructors. Type constructors are introduced by things such as:
280 -- 1) Data declarations: @data Foo = ...@ creates the @Foo@ type constructor of kind @*@
282 -- 2) Type synonyms: @type Foo = ...@ creates the @Foo@ type constructor
284 -- 3) Newtypes: @newtype Foo a = MkFoo ...@ creates the @Foo@ type constructor of kind @* -> *@
286 -- 4) Class declarations: @class Foo where@ creates the @Foo@ type constructor of kind @*@
288 -- This data type also encodes a number of primitive, built in type constructors such as those
289 -- for function and tuple types.
291 = -- | The function type constructor, @(->)@
293 tyConUnique :: Unique,
299 -- | Algebraic type constructors, which are defined to be those
300 -- arising @data@ type and @newtype@ declarations. All these
301 -- constructors are lifted and boxed. See 'AlgTyConRhs' for more
304 tyConUnique :: Unique,
309 tyConTyVars :: [TyVar], -- ^ The type variables used in the type constructor.
310 -- Invariant: length tyvars = arity
311 -- Precisely, this list scopes over:
313 -- 1. The 'algTcStupidTheta'
314 -- 2. The cached types in 'algTyConRhs.NewTyCon'
315 -- 3. The family instance types if present
317 -- Note that it does /not/ scope over the data constructors.
319 algTcGadtSyntax :: Bool, -- ^ Was the data type declared with GADT syntax?
320 -- If so, that doesn't mean it's a true GADT;
321 -- only that the "where" form was used.
322 -- This field is used only to guide pretty-printing
324 algTcStupidTheta :: [PredType], -- ^ The \"stupid theta\" for the data type
325 -- (always empty for GADTs).
326 -- A \"stupid theta\" is the context to the left
327 -- of an algebraic type declaration,
328 -- e.g. @Eq a@ in the declaration
329 -- @data Eq a => T a ...@.
331 algTcRhs :: AlgTyConRhs, -- ^ Contains information about the
332 -- data constructors of the algebraic type
334 algTcRec :: RecFlag, -- ^ Tells us whether the data type is part
335 -- of a mutually-recursive group or not
337 hasGenerics :: Bool, -- ^ Whether generic (in the -XGenerics sense)
338 -- to\/from functions are available in the exports
339 -- of the data type's source module.
341 algTcParent :: TyConParent -- ^ Gives the class or family declaration 'TyCon'
342 -- for derived 'TyCon's representing class
343 -- or family instances, respectively.
344 -- See also 'synTcParent'
347 -- | Represents the infinite family of tuple type constructors,
348 -- @()@, @(a,b)@, @(# a, b #)@ etc.
350 tyConUnique :: Unique,
354 tyConBoxed :: Boxity,
355 tyConTyVars :: [TyVar],
356 dataCon :: DataCon, -- ^ Corresponding tuple data constructor
360 -- | Represents type synonyms
362 tyConUnique :: Unique,
367 tyConTyVars :: [TyVar], -- Bound tyvars
369 synTcRhs :: SynTyConRhs, -- ^ Contains information about the
370 -- expansion of the synonym
372 synTcParent :: TyConParent -- ^ Gives the family declaration 'TyCon'
373 -- of 'TyCon's representing family instances
377 -- | Primitive types; cannot be defined in Haskell. This includes
378 -- the usual suspects (such as @Int#@) as well as foreign-imported
381 tyConUnique :: Unique,
384 tyConArity :: Arity, -- SLPJ Oct06: I'm not sure what the significance
385 -- of the arity of a primtycon is!
387 primTyConRep :: PrimRep, -- ^ Many primitive tycons are unboxed, but some are
388 -- boxed (represented by pointers). This 'PrimRep'
389 -- holds that information.
390 -- Only relevant if tc_kind = *
392 isUnLifted :: Bool, -- ^ Most primitive tycons are unlifted
393 -- (may not contain bottom)
394 -- but foreign-imported ones may be lifted
396 tyConExtName :: Maybe FastString -- ^ @Just e@ for foreign-imported types,
397 -- holds the name of the imported thing
400 -- | Any types. Like tuples, this is a potentially-infinite family of TyCons
401 -- one for each distinct Kind. They have no values at all.
402 -- Because there are infinitely many of them (like tuples) they are
403 -- defined in GHC.Prim and have names like "Any(*->*)".
404 -- Their Unique is derived from the OccName.
405 -- See Note [Any types] in TysPrim
407 tyConUnique :: Unique,
409 tc_kind :: Kind -- Never = *; that is done via PrimTyCon
410 -- See Note [Any types] in TysPrim
413 -- | Super-kinds. These are "kinds-of-kinds" and are never seen in
414 -- Haskell source programs. There are only two super-kinds: TY (aka
415 -- "box"), which is the super-kind of kinds that construct types
416 -- eventually, and CO (aka "diamond"), which is the super-kind of
417 -- kinds that just represent coercions.
419 -- Super-kinds have no kind themselves, and have arity zero
421 tyConUnique :: Unique,
425 -- | Names of the fields in an algebraic record type
426 type FieldLabel = Name
428 -- | Represents right-hand-sides of 'TyCon's for algebraic types
431 -- | Says that we know nothing about this data type, except that
432 -- it's represented by a pointer. Used when we export a data type
433 -- abstractly into an .hi file.
436 -- | Represents an open type family without a fixed right hand
437 -- side. Additional instances can appear at any time.
439 -- These are introduced by either a top level declaration:
443 -- Or an associated data type declaration, within a class declaration:
445 -- > class C a b where
449 -- | Information about those 'TyCon's derived from a @data@
450 -- declaration. This includes data types with no constructors at
453 data_cons :: [DataCon],
454 -- ^ The data type constructors; can be empty if the user
455 -- declares the type to have no constructors
457 -- INVARIANT: Kept in order of increasing 'DataCon' tag
458 -- (see the tag assignment in DataCon.mkDataCon)
460 is_enum :: Bool -- ^ Cached value: is this an enumeration type?
461 -- See Note [Enumeration types]
464 -- | Information about those 'TyCon's derived from a @newtype@ declaration
466 data_con :: DataCon, -- ^ The unique constructor for the @newtype@.
467 -- It has no existentials
469 nt_rhs :: Type, -- ^ Cached value: the argument type of the constructor,
470 -- which is just the representation type of the 'TyCon'
471 -- (remember that @newtype@s do not exist at runtime
472 -- so need a different representation type).
474 -- The free 'TyVar's of this type are the 'tyConTyVars'
475 -- from the corresponding 'TyCon'
477 nt_etad_rhs :: ([TyVar], Type),
478 -- ^ Same as the 'nt_rhs', but this time eta-reduced.
479 -- Hence the list of 'TyVar's in this field may be
480 -- shorter than the declared arity of the 'TyCon'.
482 -- See Note [Newtype eta]
483 nt_co :: CoAxiom -- The axiom coercion that creates the @newtype@ from
484 -- the representation 'Type'.
486 -- See Note [Newtype coercions]
487 -- Invariant: arity = #tvs in nt_etad_rhs;
488 -- See Note [Newtype eta]
489 -- Watch out! If any newtypes become transparent
490 -- again check Trac #1072.
493 -- | Extract those 'DataCon's that we are able to learn about. Note
494 -- that visibility in this sense does not correspond to visibility in
495 -- the context of any particular user program!
496 visibleDataCons :: AlgTyConRhs -> [DataCon]
497 visibleDataCons AbstractTyCon = []
498 visibleDataCons DataFamilyTyCon {} = []
499 visibleDataCons (DataTyCon{ data_cons = cs }) = cs
500 visibleDataCons (NewTyCon{ data_con = c }) = [c]
502 -- ^ Both type classes as well as family instances imply implicit
503 -- type constructors. These implicit type constructors refer to their parent
504 -- structure (ie, the class or family from which they derive) using a type of
505 -- the following form. We use 'TyConParent' for both algebraic and synonym
506 -- types, but the variant 'ClassTyCon' will only be used by algebraic 'TyCon's.
508 = -- | An ordinary type constructor has no parent.
511 -- | Type constructors representing a class dictionary.
513 Class -- INVARIANT: the classTyCon of this Class is the current tycon
515 -- | An *associated* type of a class.
517 Class -- The class in whose declaration the family is declared
518 -- The 'tyConTyVars' of this 'TyCon' may mention some
519 -- of the same type variables as the classTyVars of the
520 -- parent 'Class'. E.g.
527 -- Here the 'a' is shared with the 'Class', and that is
528 -- important. In an instance declaration we expect the
529 -- two to be instantiated the same way. Eg.
532 -- instanc C [x] (Tree y) where
533 -- data T c [x] = T1 x | T2 c
536 -- | Type constructors representing an instance of a type family. Parameters:
538 -- 1) The type family in question
540 -- 2) Instance types; free variables are the 'tyConTyVars'
541 -- of the current 'TyCon' (not the family one). INVARIANT:
542 -- the number of types matches the arity of the family 'TyCon'
544 -- 3) A 'CoTyCon' identifying the representation
545 -- type with the type instance family
546 | FamInstTyCon -- See Note [Data type families]
547 -- and Note [Type synonym families]
548 TyCon -- The family TyCon
549 [Type] -- Argument types (mentions the tyConTyVars of this TyCon)
550 CoAxiom -- The coercion constructor
552 -- E.g. data intance T [a] = ...
553 -- gives a representation tycon:
554 -- data R:TList a = ...
555 -- axiom co a :: T [a] ~ R:TList a
556 -- with R:TList's algTcParent = FamInstTyCon T [a] co
558 -- | Checks the invariants of a 'TyConParent' given the appropriate type class name, if any
559 okParent :: Name -> TyConParent -> Bool
560 okParent _ NoParentTyCon = True
561 okParent tc_name (AssocFamilyTyCon cls) = tc_name `elem` map tyConName (classATs cls)
562 okParent tc_name (ClassTyCon cls) = tc_name == tyConName (classTyCon cls)
563 okParent _ (FamInstTyCon fam_tc tys _co_tc) = tyConArity fam_tc == length tys
565 isNoParent :: TyConParent -> Bool
566 isNoParent NoParentTyCon = True
571 -- | Information pertaining to the expansion of a type synonym (@type@)
573 = -- | An ordinary type synonyn.
575 Type -- This 'Type' is the rhs, and may mention from 'tyConTyVars'.
576 -- It acts as a template for the expansion when the 'TyCon'
577 -- is applied to some types.
579 -- | A type synonym family e.g. @type family F x y :: * -> *@
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 %************************************************************************
684 -- | A 'CoAxiom' is a \"coercion constructor\", i.e. a named equality axiom.
686 = CoAxiom -- type equality axiom.
687 { co_ax_unique :: Unique -- unique identifier
688 , co_ax_name :: Name -- name for pretty-printing
689 , co_ax_tvs :: [TyVar] -- bound type variables
690 , co_ax_lhs :: Type -- left-hand side of the equality
691 , co_ax_rhs :: Type -- right-hand side of the equality
694 coAxiomArity :: CoAxiom -> Arity
695 coAxiomArity ax = length (co_ax_tvs ax)
697 coAxiomName :: CoAxiom -> Name
698 coAxiomName = co_ax_name
702 %************************************************************************
706 %************************************************************************
708 A PrimRep is somewhat similar to a CgRep (see codeGen/SMRep) and a
709 MachRep (see cmm/CmmExpr), although each of these types has a distinct
710 and clearly defined purpose:
712 - A PrimRep is a CgRep + information about signedness + information
713 about primitive pointers (AddrRep). Signedness and primitive
714 pointers are required when passing a primitive type to a foreign
715 function, but aren't needed for call/return conventions of Haskell
718 - A MachRep is a basic machine type (non-void, doesn't contain
719 information on pointerhood or signedness, but contains some
720 reps that don't have corresponding Haskell types).
723 -- | A 'PrimRep' is an abstraction of a type. It contains information that
724 -- the code generator needs in order to pass arguments, return results,
725 -- and store values of this type.
729 | IntRep -- ^ Signed, word-sized value
730 | WordRep -- ^ Unsigned, word-sized value
731 | Int64Rep -- ^ Signed, 64 bit value (with 32-bit words only)
732 | Word64Rep -- ^ Unsigned, 64 bit value (with 32-bit words only)
733 | AddrRep -- ^ A pointer, but /not/ to a Haskell value (use 'PtrRep')
738 instance Outputable PrimRep where
739 ppr r = text (show r)
741 -- | Find the size of a 'PrimRep', in words
742 primRepSizeW :: PrimRep -> Int
743 primRepSizeW IntRep = 1
744 primRepSizeW WordRep = 1
745 primRepSizeW Int64Rep = wORD64_SIZE `quot` wORD_SIZE
746 primRepSizeW Word64Rep= wORD64_SIZE `quot` wORD_SIZE
747 primRepSizeW FloatRep = 1 -- NB. might not take a full word
748 primRepSizeW DoubleRep= dOUBLE_SIZE `quot` wORD_SIZE
749 primRepSizeW AddrRep = 1
750 primRepSizeW PtrRep = 1
751 primRepSizeW VoidRep = 0
754 %************************************************************************
756 \subsection{TyCon Construction}
758 %************************************************************************
760 Note: the TyCon constructors all take a Kind as one argument, even though
761 they could, in principle, work out their Kind from their other arguments.
762 But to do so they need functions from Types, and that makes a nasty
763 module mutual-recursion. And they aren't called from many places.
764 So we compromise, and move their Kind calculation to the call site.
767 -- | Given the name of the function type constructor and it's kind, create the
768 -- corresponding 'TyCon'. It is reccomended to use 'TypeRep.funTyCon' if you want
769 -- this functionality
770 mkFunTyCon :: Name -> Kind -> TyCon
773 tyConUnique = nameUnique name,
779 -- | This is the making of an algebraic 'TyCon'. Notably, you have to
780 -- pass in the generic (in the -XGenerics sense) information about the
781 -- type constructor - you can get hold of it easily (see Generics
784 -> Kind -- ^ Kind of the resulting 'TyCon'
785 -> [TyVar] -- ^ 'TyVar's scoped over: see 'tyConTyVars'.
786 -- Arity is inferred from the length of this list
787 -> [PredType] -- ^ Stupid theta: see 'algTcStupidTheta'
788 -> AlgTyConRhs -- ^ Information about dat aconstructors
790 -> RecFlag -- ^ Is the 'TyCon' recursive?
791 -> Bool -- ^ Does it have generic functions? See 'hasGenerics'
792 -> Bool -- ^ Was the 'TyCon' declared with GADT syntax?
794 mkAlgTyCon name kind tyvars stupid rhs parent is_rec gen_info gadt_syn
797 tyConUnique = nameUnique name,
799 tyConArity = length tyvars,
800 tyConTyVars = tyvars,
801 algTcStupidTheta = stupid,
803 algTcParent = ASSERT( okParent name parent ) parent,
805 algTcGadtSyntax = gadt_syn,
806 hasGenerics = gen_info
809 -- | Simpler specialization of 'mkAlgTyCon' for classes
810 mkClassTyCon :: Name -> Kind -> [TyVar] -> AlgTyConRhs -> Class -> RecFlag -> TyCon
811 mkClassTyCon name kind tyvars rhs clas is_rec =
812 mkAlgTyCon name kind tyvars [] rhs (ClassTyCon clas) is_rec False False
815 -> Kind -- ^ Kind of the resulting 'TyCon'
816 -> Arity -- ^ Arity of the tuple
817 -> [TyVar] -- ^ 'TyVar's scoped over: see 'tyConTyVars'
819 -> Boxity -- ^ Whether the tuple is boxed or unboxed
820 -> Bool -- ^ Does it have generic functions? See 'hasGenerics'
822 mkTupleTyCon name kind arity tyvars con boxed gen_info
824 tyConUnique = nameUnique name,
829 tyConTyVars = tyvars,
831 hasGenerics = gen_info
834 -- ^ Foreign-imported (.NET) type constructors are represented
835 -- as primitive, but /lifted/, 'TyCons' for now. They are lifted
836 -- because the Haskell type @T@ representing the (foreign) .NET
837 -- type @T@ is actually implemented (in ILX) as a @thunk<T>@
838 mkForeignTyCon :: Name
839 -> Maybe FastString -- ^ Name of the foreign imported thing, maybe
843 mkForeignTyCon name ext_name kind arity
846 tyConUnique = nameUnique name,
849 primTyConRep = PtrRep, -- they all do
851 tyConExtName = ext_name
855 -- | Create an unlifted primitive 'TyCon', such as @Int#@
856 mkPrimTyCon :: Name -> Kind -> Arity -> PrimRep -> TyCon
857 mkPrimTyCon name kind arity rep
858 = mkPrimTyCon' name kind arity rep True
860 -- | Kind constructors
861 mkKindTyCon :: Name -> Kind -> TyCon
862 mkKindTyCon name kind
863 = mkPrimTyCon' name kind 0 VoidRep True
865 -- | Create a lifted primitive 'TyCon' such as @RealWorld@
866 mkLiftedPrimTyCon :: Name -> Kind -> Arity -> PrimRep -> TyCon
867 mkLiftedPrimTyCon name kind arity rep
868 = mkPrimTyCon' name kind arity rep False
870 mkPrimTyCon' :: Name -> Kind -> Arity -> PrimRep -> Bool -> TyCon
871 mkPrimTyCon' name kind arity rep is_unlifted
874 tyConUnique = nameUnique name,
878 isUnLifted = is_unlifted,
879 tyConExtName = Nothing
882 -- | Create a type synonym 'TyCon'
883 mkSynTyCon :: Name -> Kind -> [TyVar] -> SynTyConRhs -> TyConParent -> TyCon
884 mkSynTyCon name kind tyvars rhs parent
887 tyConUnique = nameUnique name,
889 tyConArity = length tyvars,
890 tyConTyVars = tyvars,
895 mkAnyTyCon :: Name -> Kind -> TyCon
897 = AnyTyCon { tyConName = name,
899 tyConUnique = nameUnique name }
901 -- | Create a super-kind 'TyCon'
902 mkSuperKindTyCon :: Name -> TyCon -- Super kinds always have arity zero
903 mkSuperKindTyCon name
906 tyConUnique = nameUnique name
911 isFunTyCon :: TyCon -> Bool
912 isFunTyCon (FunTyCon {}) = True
915 -- | Test if the 'TyCon' is algebraic but abstract (invisible data constructors)
916 isAbstractTyCon :: TyCon -> Bool
917 isAbstractTyCon (AlgTyCon { algTcRhs = AbstractTyCon }) = True
918 isAbstractTyCon _ = False
920 -- | Make an algebraic 'TyCon' abstract. Panics if the supplied 'TyCon' is not algebraic
921 makeTyConAbstract :: TyCon -> TyCon
922 makeTyConAbstract tc@(AlgTyCon {}) = tc { algTcRhs = AbstractTyCon }
923 makeTyConAbstract tc = pprPanic "makeTyConAbstract" (ppr tc)
925 -- | Does this 'TyCon' represent something that cannot be defined in Haskell?
926 isPrimTyCon :: TyCon -> Bool
927 isPrimTyCon (PrimTyCon {}) = True
928 isPrimTyCon _ = False
930 -- | Is this 'TyCon' unlifted (i.e. cannot contain bottom)? Note that this can only
931 -- be true for primitive and unboxed-tuple 'TyCon's
932 isUnLiftedTyCon :: TyCon -> Bool
933 isUnLiftedTyCon (PrimTyCon {isUnLifted = is_unlifted}) = is_unlifted
934 isUnLiftedTyCon (TupleTyCon {tyConBoxed = boxity}) = not (isBoxed boxity)
935 isUnLiftedTyCon _ = False
937 -- | Returns @True@ if the supplied 'TyCon' resulted from either a
938 -- @data@ or @newtype@ declaration
939 isAlgTyCon :: TyCon -> Bool
940 isAlgTyCon (AlgTyCon {}) = True
941 isAlgTyCon (TupleTyCon {}) = True
944 isDataTyCon :: TyCon -> Bool
945 -- ^ Returns @True@ for data types that are /definitely/ represented by
946 -- heap-allocated constructors. These are scrutinised by Core-level
947 -- @case@ expressions, and they get info tables allocated for them.
949 -- Generally, the function will be true for all @data@ types and false
950 -- for @newtype@s, unboxed tuples and type family 'TyCon's. But it is
951 -- not guarenteed to return @True@ in all cases that it could.
953 -- NB: for a data type family, only the /instance/ 'TyCon's
954 -- get an info table. The family declaration 'TyCon' does not
955 isDataTyCon (AlgTyCon {algTcRhs = rhs})
957 DataFamilyTyCon {} -> False
960 AbstractTyCon -> False -- We don't know, so return False
961 isDataTyCon (TupleTyCon {tyConBoxed = boxity}) = isBoxed boxity
962 isDataTyCon _ = False
964 -- | Is this 'TyCon' that for a @newtype@
965 isNewTyCon :: TyCon -> Bool
966 isNewTyCon (AlgTyCon {algTcRhs = NewTyCon {}}) = True
969 -- | Take a 'TyCon' apart into the 'TyVar's it scopes over, the 'Type' it expands
970 -- into, and (possibly) a coercion from the representation type to the @newtype@.
971 -- Returns @Nothing@ if this is not possible.
972 unwrapNewTyCon_maybe :: TyCon -> Maybe ([TyVar], Type, CoAxiom)
973 unwrapNewTyCon_maybe (AlgTyCon { tyConTyVars = tvs,
974 algTcRhs = NewTyCon { nt_co = co,
976 = Just (tvs, rhs, co)
977 unwrapNewTyCon_maybe _ = Nothing
979 isProductTyCon :: TyCon -> Bool
980 -- | A /product/ 'TyCon' must both:
982 -- 1. Have /one/ constructor
984 -- 2. /Not/ be existential
986 -- However other than this there are few restrictions: they may be @data@ or @newtype@
987 -- 'TyCon's of any boxity and may even be recursive.
988 isProductTyCon tc@(AlgTyCon {}) = case algTcRhs tc of
989 DataTyCon{ data_cons = [data_con] }
990 -> isVanillaDataCon data_con
993 isProductTyCon (TupleTyCon {}) = True
994 isProductTyCon _ = False
996 -- | Is this a 'TyCon' representing a type synonym (@type@)?
997 isSynTyCon :: TyCon -> Bool
998 isSynTyCon (SynTyCon {}) = True
1001 -- As for newtypes, it is in some contexts important to distinguish between
1002 -- closed synonyms and synonym families, as synonym families have no unique
1003 -- right hand side to which a synonym family application can expand.
1006 isDecomposableTyCon :: TyCon -> Bool
1007 -- True iff we can decompose (T a b c) into ((T a b) c)
1008 -- Specifically NOT true of synonyms (open and otherwise)
1009 isDecomposableTyCon (SynTyCon {}) = False
1010 isDecomposableTyCon _other = True
1012 -- | Is this an algebraic 'TyCon' declared with the GADT syntax?
1013 isGadtSyntaxTyCon :: TyCon -> Bool
1014 isGadtSyntaxTyCon (AlgTyCon { algTcGadtSyntax = res }) = res
1015 isGadtSyntaxTyCon _ = False
1017 -- | Is this an algebraic 'TyCon' which is just an enumeration of values?
1018 isEnumerationTyCon :: TyCon -> Bool
1019 -- See Note [Enumeration types] in TyCon
1020 isEnumerationTyCon (AlgTyCon {algTcRhs = DataTyCon { is_enum = res }}) = res
1021 isEnumerationTyCon (TupleTyCon {tyConArity = arity}) = arity == 0
1022 isEnumerationTyCon _ = False
1024 -- | Is this a 'TyCon', synonym or otherwise, that may have further instances appear?
1025 isFamilyTyCon :: TyCon -> Bool
1026 isFamilyTyCon (SynTyCon {synTcRhs = SynFamilyTyCon {}}) = True
1027 isFamilyTyCon (AlgTyCon {algTcRhs = DataFamilyTyCon {}}) = True
1028 isFamilyTyCon _ = False
1030 -- | Is this a synonym 'TyCon' that can have may have further instances appear?
1031 isSynFamilyTyCon :: TyCon -> Bool
1032 isSynFamilyTyCon (SynTyCon {synTcRhs = SynFamilyTyCon {}}) = True
1033 isSynFamilyTyCon _ = False
1035 -- | Is this a synonym 'TyCon' that can have may have further instances appear?
1036 isDataFamilyTyCon :: TyCon -> Bool
1037 isDataFamilyTyCon (AlgTyCon {algTcRhs = DataFamilyTyCon {}}) = True
1038 isDataFamilyTyCon _ = False
1040 -- | Is this a synonym 'TyCon' that can have no further instances appear?
1041 isClosedSynTyCon :: TyCon -> Bool
1042 isClosedSynTyCon tycon = isSynTyCon tycon && not (isFamilyTyCon tycon)
1044 -- | Injective 'TyCon's can be decomposed, so that
1045 -- T ty1 ~ T ty2 => ty1 ~ ty2
1046 isInjectiveTyCon :: TyCon -> Bool
1047 isInjectiveTyCon tc = not (isSynTyCon tc)
1048 -- Ultimately we may have injective associated types
1049 -- in which case this test will become more interesting
1051 -- It'd be unusual to call isInjectiveTyCon on a regular H98
1052 -- type synonym, because you should probably have expanded it first
1053 -- But regardless, it's not injective!
1055 -- | Are we able to extract informationa 'TyVar' to class argument list
1056 -- mappping from a given 'TyCon'?
1057 isTyConAssoc :: TyCon -> Bool
1058 isTyConAssoc tc = case tyConParent tc of
1059 AssocFamilyTyCon {} -> True
1062 -- The unit tycon didn't used to be classed as a tuple tycon
1063 -- but I thought that was silly so I've undone it
1064 -- If it can't be for some reason, it should be a AlgTyCon
1065 isTupleTyCon :: TyCon -> Bool
1066 -- ^ Does this 'TyCon' represent a tuple?
1068 -- NB: when compiling @Data.Tuple@, the tycons won't reply @True@ to
1069 -- 'isTupleTyCon', becuase they are built as 'AlgTyCons'. However they
1070 -- get spat into the interface file as tuple tycons, so I don't think
1072 isTupleTyCon (TupleTyCon {}) = True
1073 isTupleTyCon _ = False
1075 -- | Is this the 'TyCon' for an unboxed tuple?
1076 isUnboxedTupleTyCon :: TyCon -> Bool
1077 isUnboxedTupleTyCon (TupleTyCon {tyConBoxed = boxity}) = not (isBoxed boxity)
1078 isUnboxedTupleTyCon _ = False
1080 -- | Is this the 'TyCon' for a boxed tuple?
1081 isBoxedTupleTyCon :: TyCon -> Bool
1082 isBoxedTupleTyCon (TupleTyCon {tyConBoxed = boxity}) = isBoxed boxity
1083 isBoxedTupleTyCon _ = False
1085 -- | Extract the boxity of the given 'TyCon', if it is a 'TupleTyCon'.
1087 tupleTyConBoxity :: TyCon -> Boxity
1088 tupleTyConBoxity tc = tyConBoxed tc
1090 -- | Is this a recursive 'TyCon'?
1091 isRecursiveTyCon :: TyCon -> Bool
1092 isRecursiveTyCon (AlgTyCon {algTcRec = Recursive}) = True
1093 isRecursiveTyCon _ = False
1095 -- | Did this 'TyCon' originate from type-checking a .h*-boot file?
1096 isHiBootTyCon :: TyCon -> Bool
1097 -- Used for knot-tying in hi-boot files
1098 isHiBootTyCon (AlgTyCon {algTcRhs = AbstractTyCon}) = True
1099 isHiBootTyCon _ = False
1101 -- | Is this the 'TyCon' of a foreign-imported type constructor?
1102 isForeignTyCon :: TyCon -> Bool
1103 isForeignTyCon (PrimTyCon {tyConExtName = Just _}) = True
1104 isForeignTyCon _ = False
1106 -- | Is this a super-kind 'TyCon'?
1107 isSuperKindTyCon :: TyCon -> Bool
1108 isSuperKindTyCon (SuperKindTyCon {}) = True
1109 isSuperKindTyCon _ = False
1111 -- | Is this an AnyTyCon?
1112 isAnyTyCon :: TyCon -> Bool
1113 isAnyTyCon (AnyTyCon {}) = True
1114 isAnyTyCon _ = 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 -> [tyco] -- ^ Arguments to 'TyCon'
1146 -> Maybe ([(TyVar,tyco)],
1148 [tyco]) -- ^ 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.
1153 -- We expand (closed) synonyms only, cf. 'coreExpandTyCon_maybe'
1154 tcExpandTyCon_maybe (SynTyCon {tyConTyVars = tvs,
1155 synTcRhs = SynonymTyCon rhs }) tys
1156 = expand tvs rhs tys
1157 tcExpandTyCon_maybe _ _ = Nothing
1161 -- ^ Used to create the view /Core/ has on 'TyCon's. We expand
1162 -- not only closed synonyms like 'tcExpandTyCon_maybe',
1163 -- but also non-recursive @newtype@s
1164 coreExpandTyCon_maybe tycon tys = tcExpandTyCon_maybe tycon tys
1168 expand :: [TyVar] -> Type -- Template
1170 -> Maybe ([(TyVar,a)], Type, [a]) -- Expansion
1172 = case n_tvs `compare` length tys of
1173 LT -> Just (tvs `zip` tys, rhs, drop n_tvs tys)
1174 EQ -> Just (tvs `zip` tys, rhs, [])
1181 -- | Does this 'TyCon' have any generic to\/from functions available? See also 'hasGenerics'
1182 tyConHasGenerics :: TyCon -> Bool
1183 tyConHasGenerics (AlgTyCon {hasGenerics = hg}) = hg
1184 tyConHasGenerics (TupleTyCon {hasGenerics = hg}) = hg
1185 tyConHasGenerics _ = False -- Synonyms
1187 tyConKind :: TyCon -> Kind
1188 tyConKind (FunTyCon { tc_kind = k }) = k
1189 tyConKind (AlgTyCon { tc_kind = k }) = k
1190 tyConKind (TupleTyCon { tc_kind = k }) = k
1191 tyConKind (SynTyCon { tc_kind = k }) = k
1192 tyConKind (PrimTyCon { tc_kind = k }) = k
1193 tyConKind (AnyTyCon { tc_kind = k }) = k
1194 tyConKind tc = pprPanic "tyConKind" (ppr tc) -- SuperKindTyCon and CoTyCon
1196 tyConHasKind :: TyCon -> Bool
1197 tyConHasKind (SuperKindTyCon {}) = False
1198 tyConHasKind _ = True
1200 -- | As 'tyConDataCons_maybe', but returns the empty list of constructors if no constructors
1202 tyConDataCons :: TyCon -> [DataCon]
1203 -- It's convenient for tyConDataCons to return the
1204 -- empty list for type synonyms etc
1205 tyConDataCons tycon = tyConDataCons_maybe tycon `orElse` []
1207 -- | Determine the 'DataCon's originating from the given 'TyCon', if the 'TyCon' is the
1208 -- sort that can have any constructors (note: this does not include abstract algebraic types)
1209 tyConDataCons_maybe :: TyCon -> Maybe [DataCon]
1210 tyConDataCons_maybe (AlgTyCon {algTcRhs = DataTyCon { data_cons = cons }}) = Just cons
1211 tyConDataCons_maybe (AlgTyCon {algTcRhs = NewTyCon { data_con = con }}) = Just [con]
1212 tyConDataCons_maybe (TupleTyCon {dataCon = con}) = Just [con]
1213 tyConDataCons_maybe _ = Nothing
1215 -- | Determine the number of value constructors a 'TyCon' has. Panics if the 'TyCon'
1216 -- is not algebraic or a tuple
1217 tyConFamilySize :: TyCon -> Int
1218 tyConFamilySize (AlgTyCon {algTcRhs = DataTyCon {data_cons = cons}}) =
1220 tyConFamilySize (AlgTyCon {algTcRhs = NewTyCon {}}) = 1
1221 tyConFamilySize (AlgTyCon {algTcRhs = DataFamilyTyCon {}}) = 0
1222 tyConFamilySize (TupleTyCon {}) = 1
1223 tyConFamilySize other = pprPanic "tyConFamilySize:" (ppr other)
1225 -- | Extract an 'AlgTyConRhs' with information about data constructors from an algebraic or tuple
1226 -- 'TyCon'. Panics for any other sort of 'TyCon'
1227 algTyConRhs :: TyCon -> AlgTyConRhs
1228 algTyConRhs (AlgTyCon {algTcRhs = rhs}) = rhs
1229 algTyConRhs (TupleTyCon {dataCon = con, tyConArity = arity})
1230 = DataTyCon { data_cons = [con], is_enum = arity == 0 }
1231 algTyConRhs other = pprPanic "algTyConRhs" (ppr other)
1235 -- | Extract the bound type variables and type expansion of a type synonym 'TyCon'. Panics if the
1236 -- 'TyCon' is not a synonym
1237 newTyConRhs :: TyCon -> ([TyVar], Type)
1238 newTyConRhs (AlgTyCon {tyConTyVars = tvs, algTcRhs = NewTyCon { nt_rhs = rhs }}) = (tvs, rhs)
1239 newTyConRhs tycon = pprPanic "newTyConRhs" (ppr tycon)
1241 -- | Extract the bound type variables and type expansion of an eta-contracted type synonym 'TyCon'.
1242 -- Panics if the 'TyCon' is not a synonym
1243 newTyConEtadRhs :: TyCon -> ([TyVar], Type)
1244 newTyConEtadRhs (AlgTyCon {algTcRhs = NewTyCon { nt_etad_rhs = tvs_rhs }}) = tvs_rhs
1245 newTyConEtadRhs tycon = pprPanic "newTyConEtadRhs" (ppr tycon)
1247 -- | Extracts the @newtype@ coercion from such a 'TyCon', which can be used to construct something
1248 -- with the @newtype@s type from its representation type (right hand side). If the supplied 'TyCon'
1249 -- is not a @newtype@, returns @Nothing@
1250 newTyConCo_maybe :: TyCon -> Maybe CoAxiom
1251 newTyConCo_maybe (AlgTyCon {algTcRhs = NewTyCon { nt_co = co }}) = Just co
1252 newTyConCo_maybe _ = Nothing
1254 newTyConCo :: TyCon -> CoAxiom
1255 newTyConCo tc = case newTyConCo_maybe tc of
1257 Nothing -> pprPanic "newTyConCo" (ppr tc)
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 ----------------------------------------------------------------------------
1328 -- | Is this 'TyCon' that for a family instance, be that for a synonym or an
1329 -- algebraic family instance?
1330 isFamInstTyCon :: TyCon -> Bool
1331 isFamInstTyCon tc = case tyConParent tc of
1332 FamInstTyCon {} -> True
1335 tyConFamInstSig_maybe :: TyCon -> Maybe (TyCon, [Type], CoAxiom)
1336 tyConFamInstSig_maybe tc
1337 = case tyConParent tc of
1338 FamInstTyCon f ts co_tc -> Just (f, ts, co_tc)
1341 -- | If this 'TyCon' is that of a family instance, return the family in question
1342 -- and the instance types. Otherwise, return @Nothing@
1343 tyConFamInst_maybe :: TyCon -> Maybe (TyCon, [Type])
1344 tyConFamInst_maybe tc
1345 = case tyConParent tc of
1346 FamInstTyCon f ts _ -> Just (f, ts)
1349 -- | If this 'TyCon' is that of a family instance, return a 'TyCon' which represents
1350 -- a coercion identifying the representation type with the type instance family.
1351 -- Otherwise, return @Nothing@
1352 tyConFamilyCoercion_maybe :: TyCon -> Maybe CoAxiom
1353 tyConFamilyCoercion_maybe tc
1354 = case tyConParent tc of
1355 FamInstTyCon _ _ co -> Just co
1360 %************************************************************************
1362 \subsection[TyCon-instances]{Instance declarations for @TyCon@}
1364 %************************************************************************
1366 @TyCon@s are compared by comparing their @Unique@s.
1368 The strictness analyser needs @Ord@. It is a lexicographic order with
1369 the property @(a<=b) || (b<=a)@.
1372 instance Eq TyCon where
1373 a == b = case (a `compare` b) of { EQ -> True; _ -> False }
1374 a /= b = case (a `compare` b) of { EQ -> False; _ -> True }
1376 instance Ord TyCon where
1377 a <= b = case (a `compare` b) of { LT -> True; EQ -> True; GT -> False }
1378 a < b = case (a `compare` b) of { LT -> True; EQ -> False; GT -> False }
1379 a >= b = case (a `compare` b) of { LT -> False; EQ -> True; GT -> True }
1380 a > b = case (a `compare` b) of { LT -> False; EQ -> False; GT -> True }
1381 compare a b = getUnique a `compare` getUnique b
1383 instance Uniquable TyCon where
1384 getUnique tc = tyConUnique tc
1386 instance Outputable TyCon where
1387 ppr tc = ppr (getName tc)
1389 instance NamedThing TyCon where
1392 instance Data.Typeable TyCon where
1393 typeOf _ = Data.mkTyConApp (Data.mkTyCon "TyCon") []
1395 instance Data.Data TyCon where
1397 toConstr _ = abstractConstr "TyCon"
1398 gunfold _ _ = error "gunfold"
1399 dataTypeOf _ = mkNoRepType "TyCon"
1402 instance Eq CoAxiom where
1403 a == b = case (a `compare` b) of { EQ -> True; _ -> False }
1404 a /= b = case (a `compare` b) of { EQ -> False; _ -> True }
1406 instance Ord CoAxiom where
1407 a <= b = case (a `compare` b) of { LT -> True; EQ -> True; GT -> False }
1408 a < b = case (a `compare` b) of { LT -> True; EQ -> False; GT -> False }
1409 a >= b = case (a `compare` b) of { LT -> False; EQ -> True; GT -> True }
1410 a > b = case (a `compare` b) of { LT -> False; EQ -> False; GT -> True }
1411 compare a b = getUnique a `compare` getUnique b
1413 instance Uniquable CoAxiom where
1414 getUnique = co_ax_unique
1416 instance Outputable CoAxiom where
1419 instance NamedThing CoAxiom where
1420 getName = co_ax_name
1422 instance Data.Typeable CoAxiom where
1423 typeOf _ = Data.mkTyConApp (Data.mkTyCon "CoAxiom") []
1425 instance Data.Data CoAxiom where
1427 toConstr _ = abstractConstr "CoAxiom"
1428 gunfold _ _ = error "gunfold"
1429 dataTypeOf _ = mkNoRepType "CoAxiom"