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 Note [Newtype coercions]
594 ~~~~~~~~~~~~~~~~~~~~~~~~
595 The NewTyCon field nt_co is a a TyCon (a coercion constructor in fact)
596 which is used for coercing from the representation type of the
597 newtype, to the newtype itself. For example,
599 newtype T a = MkT (a -> a)
601 the NewTyCon for T will contain nt_co = CoT where CoT t : T t ~ t ->
602 t. This TyCon is a CoTyCon, so it does not have a kind on its
603 own; it basically has its own typing rule for the fully-applied
604 version. If the newtype T has k type variables then CoT has arity at
605 most k. In the case that the right hand side is a type application
606 ending with the same type variables as the left hand side, we
607 "eta-contract" the coercion. So if we had
609 newtype S a = MkT [a]
611 then we would generate the arity 0 coercion CoS : S ~ []. The
612 primary reason we do this is to make newtype deriving cleaner.
614 In the paper we'd write
615 axiom CoT : (forall t. T t) ~ (forall t. [t])
616 and then when we used CoT at a particular type, s, we'd say
618 which encodes as (TyConApp instCoercionTyCon [TyConApp CoT [], s])
620 But in GHC we instead make CoT into a new piece of type syntax, CoTyCon,
621 (like instCoercionTyCon, symCoercionTyCon etc), which must always
622 be saturated, but which encodes as
624 In the vocabulary of the paper it's as if we had axiom declarations
626 axiom CoT t : T t ~ [t]
631 newtype Parser m a = MkParser (Foogle m a)
632 Are these two types equal (to Core)?
635 Well, yes. But to see that easily we eta-reduce the RHS type of
636 Parser, in this case to ([], Froogle), so that even unsaturated applications
637 of Parser will work right. This eta reduction is done when the type
638 constructor is built, and cached in NewTyCon. The cached field is
639 only used in coreExpandTyCon_maybe.
641 Here's an example that I think showed up in practice
643 newtype T a = MkT [a]
644 newtype Foo m = MkFoo (forall a. m a -> Int)
650 w2 = MkFoo (\(MkT x) -> case w1 of MkFoo f -> f x)
652 After desugaring, and discarding the data constructors for the newtypes,
656 And now Lint complains unless Foo T == Foo [], and that requires T==[]
658 This point carries over to the newtype coercion, because we need to
660 w2 = w1 `cast` Foo CoT
662 so the coercion tycon CoT must have
667 %************************************************************************
671 %************************************************************************
673 A PrimRep is somewhat similar to a CgRep (see codeGen/SMRep) and a
674 MachRep (see cmm/CmmExpr), although each of these types has a distinct
675 and clearly defined purpose:
677 - A PrimRep is a CgRep + information about signedness + information
678 about primitive pointers (AddrRep). Signedness and primitive
679 pointers are required when passing a primitive type to a foreign
680 function, but aren't needed for call/return conventions of Haskell
683 - A MachRep is a basic machine type (non-void, doesn't contain
684 information on pointerhood or signedness, but contains some
685 reps that don't have corresponding Haskell types).
688 -- | A 'PrimRep' is an abstraction of a type. It contains information that
689 -- the code generator needs in order to pass arguments, return results,
690 -- and store values of this type.
694 | IntRep -- ^ Signed, word-sized value
695 | WordRep -- ^ Unsigned, word-sized value
696 | Int64Rep -- ^ Signed, 64 bit value (with 32-bit words only)
697 | Word64Rep -- ^ Unsigned, 64 bit value (with 32-bit words only)
698 | AddrRep -- ^ A pointer, but /not/ to a Haskell value (use 'PtrRep')
703 instance Outputable PrimRep where
704 ppr r = text (show r)
706 -- | Find the size of a 'PrimRep', in words
707 primRepSizeW :: PrimRep -> Int
708 primRepSizeW IntRep = 1
709 primRepSizeW WordRep = 1
710 primRepSizeW Int64Rep = wORD64_SIZE `quot` wORD_SIZE
711 primRepSizeW Word64Rep= wORD64_SIZE `quot` wORD_SIZE
712 primRepSizeW FloatRep = 1 -- NB. might not take a full word
713 primRepSizeW DoubleRep= dOUBLE_SIZE `quot` wORD_SIZE
714 primRepSizeW AddrRep = 1
715 primRepSizeW PtrRep = 1
716 primRepSizeW VoidRep = 0
719 %************************************************************************
721 \subsection{TyCon Construction}
723 %************************************************************************
725 Note: the TyCon constructors all take a Kind as one argument, even though
726 they could, in principle, work out their Kind from their other arguments.
727 But to do so they need functions from Types, and that makes a nasty
728 module mutual-recursion. And they aren't called from many places.
729 So we compromise, and move their Kind calculation to the call site.
732 -- | Given the name of the function type constructor and it's kind, create the
733 -- corresponding 'TyCon'. It is reccomended to use 'TypeRep.funTyCon' if you want
734 -- this functionality
735 mkFunTyCon :: Name -> Kind -> TyCon
738 tyConUnique = nameUnique name,
744 -- | This is the making of an algebraic 'TyCon'. Notably, you have to
745 -- pass in the generic (in the -XGenerics sense) information about the
746 -- type constructor - you can get hold of it easily (see Generics
749 -> Kind -- ^ Kind of the resulting 'TyCon'
750 -> [TyVar] -- ^ 'TyVar's scoped over: see 'tyConTyVars'.
751 -- Arity is inferred from the length of this list
752 -> [PredType] -- ^ Stupid theta: see 'algTcStupidTheta'
753 -> AlgTyConRhs -- ^ Information about dat aconstructors
755 -> RecFlag -- ^ Is the 'TyCon' recursive?
756 -> Bool -- ^ Does it have generic functions? See 'hasGenerics'
757 -> Bool -- ^ Was the 'TyCon' declared with GADT syntax?
759 mkAlgTyCon name kind tyvars stupid rhs parent is_rec gen_info gadt_syn
762 tyConUnique = nameUnique name,
764 tyConArity = length tyvars,
765 tyConTyVars = tyvars,
766 algTcStupidTheta = stupid,
768 algTcParent = ASSERT( okParent name parent ) parent,
770 algTcGadtSyntax = gadt_syn,
771 hasGenerics = gen_info
774 -- | Simpler specialization of 'mkAlgTyCon' for classes
775 mkClassTyCon :: Name -> Kind -> [TyVar] -> AlgTyConRhs -> Class -> RecFlag -> TyCon
776 mkClassTyCon name kind tyvars rhs clas is_rec =
777 mkAlgTyCon name kind tyvars [] rhs (ClassTyCon clas) is_rec False False
780 -> Kind -- ^ Kind of the resulting 'TyCon'
781 -> Arity -- ^ Arity of the tuple
782 -> [TyVar] -- ^ 'TyVar's scoped over: see 'tyConTyVars'
784 -> Boxity -- ^ Whether the tuple is boxed or unboxed
785 -> Bool -- ^ Does it have generic functions? See 'hasGenerics'
787 mkTupleTyCon name kind arity tyvars con boxed gen_info
789 tyConUnique = nameUnique name,
794 tyConTyVars = tyvars,
796 hasGenerics = gen_info
799 -- ^ Foreign-imported (.NET) type constructors are represented
800 -- as primitive, but /lifted/, 'TyCons' for now. They are lifted
801 -- because the Haskell type @T@ representing the (foreign) .NET
802 -- type @T@ is actually implemented (in ILX) as a @thunk<T>@
803 mkForeignTyCon :: Name
804 -> Maybe FastString -- ^ Name of the foreign imported thing, maybe
808 mkForeignTyCon name ext_name kind arity
811 tyConUnique = nameUnique name,
814 primTyConRep = PtrRep, -- they all do
816 tyConExtName = ext_name
820 -- | Create an unlifted primitive 'TyCon', such as @Int#@
821 mkPrimTyCon :: Name -> Kind -> Arity -> PrimRep -> TyCon
822 mkPrimTyCon name kind arity rep
823 = mkPrimTyCon' name kind arity rep True
825 -- | Kind constructors
826 mkKindTyCon :: Name -> Kind -> TyCon
827 mkKindTyCon name kind
828 = mkPrimTyCon' name kind 0 VoidRep True
830 -- | Create a lifted primitive 'TyCon' such as @RealWorld@
831 mkLiftedPrimTyCon :: Name -> Kind -> Arity -> PrimRep -> TyCon
832 mkLiftedPrimTyCon name kind arity rep
833 = mkPrimTyCon' name kind arity rep False
835 mkPrimTyCon' :: Name -> Kind -> Arity -> PrimRep -> Bool -> TyCon
836 mkPrimTyCon' name kind arity rep is_unlifted
839 tyConUnique = nameUnique name,
843 isUnLifted = is_unlifted,
844 tyConExtName = Nothing
847 -- | Create a type synonym 'TyCon'
848 mkSynTyCon :: Name -> Kind -> [TyVar] -> SynTyConRhs -> TyConParent -> TyCon
849 mkSynTyCon name kind tyvars rhs parent
852 tyConUnique = nameUnique name,
854 tyConArity = length tyvars,
855 tyConTyVars = tyvars,
860 -- | Create a coercion 'TyCon'
861 mkCoercionTyCon :: Name -> Arity
864 mkCoercionTyCon name arity desc
867 tyConUnique = nameUnique name,
871 mkAnyTyCon :: Name -> Kind -> TyCon
873 = AnyTyCon { tyConName = name,
875 tyConUnique = nameUnique name }
877 -- | Create a super-kind 'TyCon'
878 mkSuperKindTyCon :: Name -> TyCon -- Super kinds always have arity zero
879 mkSuperKindTyCon name
882 tyConUnique = nameUnique name
887 isFunTyCon :: TyCon -> Bool
888 isFunTyCon (FunTyCon {}) = True
891 -- | Test if the 'TyCon' is algebraic but abstract (invisible data constructors)
892 isAbstractTyCon :: TyCon -> Bool
893 isAbstractTyCon (AlgTyCon { algTcRhs = AbstractTyCon }) = True
894 isAbstractTyCon _ = False
896 -- | Make an algebraic 'TyCon' abstract. Panics if the supplied 'TyCon' is not algebraic
897 makeTyConAbstract :: TyCon -> TyCon
898 makeTyConAbstract tc@(AlgTyCon {}) = tc { algTcRhs = AbstractTyCon }
899 makeTyConAbstract tc = pprPanic "makeTyConAbstract" (ppr tc)
901 -- | Does this 'TyCon' represent something that cannot be defined in Haskell?
902 isPrimTyCon :: TyCon -> Bool
903 isPrimTyCon (PrimTyCon {}) = True
904 isPrimTyCon _ = False
906 -- | Is this 'TyCon' unlifted (i.e. cannot contain bottom)? Note that this can only
907 -- be true for primitive and unboxed-tuple 'TyCon's
908 isUnLiftedTyCon :: TyCon -> Bool
909 isUnLiftedTyCon (PrimTyCon {isUnLifted = is_unlifted}) = is_unlifted
910 isUnLiftedTyCon (TupleTyCon {tyConBoxed = boxity}) = not (isBoxed boxity)
911 isUnLiftedTyCon _ = False
913 -- | Returns @True@ if the supplied 'TyCon' resulted from either a
914 -- @data@ or @newtype@ declaration
915 isAlgTyCon :: TyCon -> Bool
916 isAlgTyCon (AlgTyCon {}) = True
917 isAlgTyCon (TupleTyCon {}) = True
920 isDataTyCon :: TyCon -> Bool
921 -- ^ Returns @True@ for data types that are /definitely/ represented by
922 -- heap-allocated constructors. These are scrutinised by Core-level
923 -- @case@ expressions, and they get info tables allocated for them.
925 -- Generally, the function will be true for all @data@ types and false
926 -- for @newtype@s, unboxed tuples and type family 'TyCon's. But it is
927 -- not guarenteed to return @True@ in all cases that it could.
929 -- NB: for a data type family, only the /instance/ 'TyCon's
930 -- get an info table. The family declaration 'TyCon' does not
931 isDataTyCon (AlgTyCon {algTcRhs = rhs})
933 DataFamilyTyCon {} -> False
936 AbstractTyCon -> False -- We don't know, so return False
937 isDataTyCon (TupleTyCon {tyConBoxed = boxity}) = isBoxed boxity
938 isDataTyCon _ = False
940 -- | Is this 'TyCon' that for a @newtype@
941 isNewTyCon :: TyCon -> Bool
942 isNewTyCon (AlgTyCon {algTcRhs = NewTyCon {}}) = True
945 -- | Take a 'TyCon' apart into the 'TyVar's it scopes over, the 'Type' it expands
946 -- into, and (possibly) a coercion from the representation type to the @newtype@.
947 -- Returns @Nothing@ if this is not possible.
948 unwrapNewTyCon_maybe :: TyCon -> Maybe ([TyVar], Type, Maybe TyCon)
949 unwrapNewTyCon_maybe (AlgTyCon { tyConTyVars = tvs,
950 algTcRhs = NewTyCon { nt_co = mb_co,
952 = Just (tvs, rhs, mb_co)
953 unwrapNewTyCon_maybe _ = Nothing
955 isProductTyCon :: TyCon -> Bool
956 -- | A /product/ 'TyCon' must both:
958 -- 1. Have /one/ constructor
960 -- 2. /Not/ be existential
962 -- However other than this there are few restrictions: they may be @data@ or @newtype@
963 -- 'TyCon's of any boxity and may even be recursive.
964 isProductTyCon tc@(AlgTyCon {}) = case algTcRhs tc of
965 DataTyCon{ data_cons = [data_con] }
966 -> isVanillaDataCon data_con
969 isProductTyCon (TupleTyCon {}) = True
970 isProductTyCon _ = False
972 -- | Is this a 'TyCon' representing a type synonym (@type@)?
973 isSynTyCon :: TyCon -> Bool
974 isSynTyCon (SynTyCon {}) = True
977 -- As for newtypes, it is in some contexts important to distinguish between
978 -- closed synonyms and synonym families, as synonym families have no unique
979 -- right hand side to which a synonym family application can expand.
982 isDecomposableTyCon :: TyCon -> Bool
983 -- True iff we can decompose (T a b c) into ((T a b) c)
984 -- Specifically NOT true of synonyms (open and otherwise) and coercions
985 isDecomposableTyCon (SynTyCon {}) = False
986 isDecomposableTyCon (CoTyCon {}) = False
987 isDecomposableTyCon _other = True
989 -- | Is this an algebraic 'TyCon' declared with the GADT syntax?
990 isGadtSyntaxTyCon :: TyCon -> Bool
991 isGadtSyntaxTyCon (AlgTyCon { algTcGadtSyntax = res }) = res
992 isGadtSyntaxTyCon _ = False
994 -- | Is this an algebraic 'TyCon' which is just an enumeration of values?
995 isEnumerationTyCon :: TyCon -> Bool
996 -- See Note [Enumeration types] in TyCon
997 isEnumerationTyCon (AlgTyCon {algTcRhs = DataTyCon { is_enum = res }}) = res
998 isEnumerationTyCon (TupleTyCon {tyConArity = arity}) = arity == 0
999 isEnumerationTyCon _ = False
1001 -- | Is this a 'TyCon', synonym or otherwise, that may have further instances appear?
1002 isFamilyTyCon :: TyCon -> Bool
1003 isFamilyTyCon (SynTyCon {synTcRhs = SynFamilyTyCon {}}) = True
1004 isFamilyTyCon (AlgTyCon {algTcRhs = DataFamilyTyCon {}}) = True
1005 isFamilyTyCon _ = False
1007 -- | Is this a synonym 'TyCon' that can have may have further instances appear?
1008 isSynFamilyTyCon :: TyCon -> Bool
1009 isSynFamilyTyCon (SynTyCon {synTcRhs = SynFamilyTyCon {}}) = True
1010 isSynFamilyTyCon _ = False
1012 -- | Is this a synonym 'TyCon' that can have may have further instances appear?
1013 isDataFamilyTyCon :: TyCon -> Bool
1014 isDataFamilyTyCon (AlgTyCon {algTcRhs = DataFamilyTyCon {}}) = True
1015 isDataFamilyTyCon _ = False
1017 -- | Is this a synonym 'TyCon' that can have no further instances appear?
1018 isClosedSynTyCon :: TyCon -> Bool
1019 isClosedSynTyCon tycon = isSynTyCon tycon && not (isFamilyTyCon tycon)
1021 -- | Injective 'TyCon's can be decomposed, so that
1022 -- T ty1 ~ T ty2 => ty1 ~ ty2
1023 isInjectiveTyCon :: TyCon -> Bool
1024 isInjectiveTyCon tc = not (isSynTyCon tc)
1025 -- Ultimately we may have injective associated types
1026 -- in which case this test will become more interesting
1028 -- It'd be unusual to call isInjectiveTyCon on a regular H98
1029 -- type synonym, because you should probably have expanded it first
1030 -- But regardless, it's not injective!
1032 -- | Are we able to extract informationa 'TyVar' to class argument list
1033 -- mappping from a given 'TyCon'?
1034 isTyConAssoc :: TyCon -> Bool
1035 isTyConAssoc tc = case tyConParent tc of
1036 AssocFamilyTyCon {} -> True
1039 -- The unit tycon didn't used to be classed as a tuple tycon
1040 -- but I thought that was silly so I've undone it
1041 -- If it can't be for some reason, it should be a AlgTyCon
1042 isTupleTyCon :: TyCon -> Bool
1043 -- ^ Does this 'TyCon' represent a tuple?
1045 -- NB: when compiling @Data.Tuple@, the tycons won't reply @True@ to
1046 -- 'isTupleTyCon', becuase they are built as 'AlgTyCons'. However they
1047 -- get spat into the interface file as tuple tycons, so I don't think
1049 isTupleTyCon (TupleTyCon {}) = True
1050 isTupleTyCon _ = False
1052 -- | Is this the 'TyCon' for an unboxed tuple?
1053 isUnboxedTupleTyCon :: TyCon -> Bool
1054 isUnboxedTupleTyCon (TupleTyCon {tyConBoxed = boxity}) = not (isBoxed boxity)
1055 isUnboxedTupleTyCon _ = False
1057 -- | Is this the 'TyCon' for a boxed tuple?
1058 isBoxedTupleTyCon :: TyCon -> Bool
1059 isBoxedTupleTyCon (TupleTyCon {tyConBoxed = boxity}) = isBoxed boxity
1060 isBoxedTupleTyCon _ = False
1062 -- | Extract the boxity of the given 'TyCon', if it is a 'TupleTyCon'.
1064 tupleTyConBoxity :: TyCon -> Boxity
1065 tupleTyConBoxity tc = tyConBoxed tc
1067 -- | Is this a recursive 'TyCon'?
1068 isRecursiveTyCon :: TyCon -> Bool
1069 isRecursiveTyCon (AlgTyCon {algTcRec = Recursive}) = True
1070 isRecursiveTyCon _ = False
1072 -- | Did this 'TyCon' originate from type-checking a .h*-boot file?
1073 isHiBootTyCon :: TyCon -> Bool
1074 -- Used for knot-tying in hi-boot files
1075 isHiBootTyCon (AlgTyCon {algTcRhs = AbstractTyCon}) = True
1076 isHiBootTyCon _ = False
1078 -- | Is this the 'TyCon' of a foreign-imported type constructor?
1079 isForeignTyCon :: TyCon -> Bool
1080 isForeignTyCon (PrimTyCon {tyConExtName = Just _}) = True
1081 isForeignTyCon _ = False
1083 -- | Is this a super-kind 'TyCon'?
1084 isSuperKindTyCon :: TyCon -> Bool
1085 isSuperKindTyCon (SuperKindTyCon {}) = True
1086 isSuperKindTyCon _ = False
1088 -- | Is this an AnyTyCon?
1089 isAnyTyCon :: TyCon -> Bool
1090 isAnyTyCon (AnyTyCon {}) = True
1091 isAnyTyCon _ = False
1093 -- | Attempt to pull a 'TyCon' apart into the arity and 'coKindFun' of
1094 -- a coercion 'TyCon'. Returns @Nothing@ if the 'TyCon' is not of the
1096 isCoercionTyCon_maybe :: TyCon -> Maybe (Arity, CoTyConDesc)
1097 isCoercionTyCon_maybe (CoTyCon {tyConArity = ar, coTcDesc = desc})
1099 isCoercionTyCon_maybe _ = Nothing
1101 -- | Is this a 'TyCon' that represents a coercion?
1102 isCoercionTyCon :: TyCon -> Bool
1103 isCoercionTyCon (CoTyCon {}) = True
1104 isCoercionTyCon _ = False
1106 -- | Identifies implicit tycons that, in particular, do not go into interface
1107 -- files (because they are implicitly reconstructed when the interface is
1112 -- * Associated families are implicit, as they are re-constructed from
1113 -- the class declaration in which they reside, and
1115 -- * Family instances are /not/ implicit as they represent the instance body
1116 -- (similar to a @dfun@ does that for a class instance).
1117 isImplicitTyCon :: TyCon -> Bool
1118 isImplicitTyCon tycon | isTyConAssoc tycon = True
1119 | isSynTyCon tycon = False
1120 | isAlgTyCon tycon = isClassTyCon tycon ||
1122 isImplicitTyCon _other = True
1123 -- catches: FunTyCon, PrimTyCon,
1124 -- CoTyCon, SuperKindTyCon
1128 -----------------------------------------------
1129 -- Expand type-constructor applications
1130 -----------------------------------------------
1133 tcExpandTyCon_maybe, coreExpandTyCon_maybe
1135 -> [Type] -- ^ Arguments to 'TyCon'
1136 -> Maybe ([(TyVar,Type)],
1138 [Type]) -- ^ Returns a 'TyVar' substitution, the body type
1139 -- of the synonym (not yet substituted) and any arguments
1140 -- remaining from the application
1142 -- ^ Used to create the view the /typechecker/ has on 'TyCon's. We expand (closed) synonyms only, cf. 'coreExpandTyCon_maybe'
1143 tcExpandTyCon_maybe (SynTyCon {tyConTyVars = tvs,
1144 synTcRhs = SynonymTyCon rhs }) tys
1145 = expand tvs rhs tys
1146 tcExpandTyCon_maybe _ _ = Nothing
1150 -- ^ Used to create the view /Core/ has on 'TyCon's. We expand not only closed synonyms like 'tcExpandTyCon_maybe',
1151 -- but also non-recursive @newtype@s
1152 coreExpandTyCon_maybe (AlgTyCon {
1153 algTcRhs = NewTyCon { nt_etad_rhs = etad_rhs, nt_co = Nothing }}) tys
1154 = case etad_rhs of -- Don't do this in the pattern match, lest we accidentally
1155 -- match the etad_rhs of a *recursive* newtype
1156 (tvs,rhs) -> expand tvs rhs tys
1158 coreExpandTyCon_maybe tycon tys = tcExpandTyCon_maybe tycon tys
1162 expand :: [TyVar] -> Type -- Template
1164 -> Maybe ([(TyVar,Type)], Type, [Type]) -- Expansion
1166 = case n_tvs `compare` length tys of
1167 LT -> Just (tvs `zip` tys, rhs, drop n_tvs tys)
1168 EQ -> Just (tvs `zip` tys, rhs, [])
1175 -- | Does this 'TyCon' have any generic to\/from functions available? See also 'hasGenerics'
1176 tyConHasGenerics :: TyCon -> Bool
1177 tyConHasGenerics (AlgTyCon {hasGenerics = hg}) = hg
1178 tyConHasGenerics (TupleTyCon {hasGenerics = hg}) = hg
1179 tyConHasGenerics _ = False -- Synonyms
1181 tyConKind :: TyCon -> Kind
1182 tyConKind (FunTyCon { tc_kind = k }) = k
1183 tyConKind (AlgTyCon { tc_kind = k }) = k
1184 tyConKind (TupleTyCon { tc_kind = k }) = k
1185 tyConKind (SynTyCon { tc_kind = k }) = k
1186 tyConKind (PrimTyCon { tc_kind = k }) = k
1187 tyConKind (AnyTyCon { tc_kind = k }) = k
1188 tyConKind tc = pprPanic "tyConKind" (ppr tc) -- SuperKindTyCon and CoTyCon
1190 tyConHasKind :: TyCon -> Bool
1191 tyConHasKind (SuperKindTyCon {}) = False
1192 tyConHasKind (CoTyCon {}) = False
1193 tyConHasKind _ = True
1195 -- | As 'tyConDataCons_maybe', but returns the empty list of constructors if no constructors
1197 tyConDataCons :: TyCon -> [DataCon]
1198 -- It's convenient for tyConDataCons to return the
1199 -- empty list for type synonyms etc
1200 tyConDataCons tycon = tyConDataCons_maybe tycon `orElse` []
1202 -- | Determine the 'DataCon's originating from the given 'TyCon', if the 'TyCon' is the
1203 -- sort that can have any constructors (note: this does not include abstract algebraic types)
1204 tyConDataCons_maybe :: TyCon -> Maybe [DataCon]
1205 tyConDataCons_maybe (AlgTyCon {algTcRhs = DataTyCon { data_cons = cons }}) = Just cons
1206 tyConDataCons_maybe (AlgTyCon {algTcRhs = NewTyCon { data_con = con }}) = Just [con]
1207 tyConDataCons_maybe (TupleTyCon {dataCon = con}) = Just [con]
1208 tyConDataCons_maybe _ = Nothing
1210 -- | Determine the number of value constructors a 'TyCon' has. Panics if the 'TyCon'
1211 -- is not algebraic or a tuple
1212 tyConFamilySize :: TyCon -> Int
1213 tyConFamilySize (AlgTyCon {algTcRhs = DataTyCon {data_cons = cons}}) =
1215 tyConFamilySize (AlgTyCon {algTcRhs = NewTyCon {}}) = 1
1216 tyConFamilySize (AlgTyCon {algTcRhs = DataFamilyTyCon {}}) = 0
1217 tyConFamilySize (TupleTyCon {}) = 1
1218 tyConFamilySize other = pprPanic "tyConFamilySize:" (ppr other)
1220 -- | Extract an 'AlgTyConRhs' with information about data constructors from an algebraic or tuple
1221 -- 'TyCon'. Panics for any other sort of 'TyCon'
1222 algTyConRhs :: TyCon -> AlgTyConRhs
1223 algTyConRhs (AlgTyCon {algTcRhs = rhs}) = rhs
1224 algTyConRhs (TupleTyCon {dataCon = con, tyConArity = arity})
1225 = DataTyCon { data_cons = [con], is_enum = arity == 0 }
1226 algTyConRhs other = pprPanic "algTyConRhs" (ppr other)
1230 -- | Extract the bound type variables and type expansion of a type synonym 'TyCon'. Panics if the
1231 -- 'TyCon' is not a synonym
1232 newTyConRhs :: TyCon -> ([TyVar], Type)
1233 newTyConRhs (AlgTyCon {tyConTyVars = tvs, algTcRhs = NewTyCon { nt_rhs = rhs }}) = (tvs, rhs)
1234 newTyConRhs tycon = pprPanic "newTyConRhs" (ppr tycon)
1236 -- | Extract the bound type variables and type expansion of an eta-contracted type synonym 'TyCon'.
1237 -- Panics if the 'TyCon' is not a synonym
1238 newTyConEtadRhs :: TyCon -> ([TyVar], Type)
1239 newTyConEtadRhs (AlgTyCon {algTcRhs = NewTyCon { nt_etad_rhs = tvs_rhs }}) = tvs_rhs
1240 newTyConEtadRhs tycon = pprPanic "newTyConEtadRhs" (ppr tycon)
1242 -- | Extracts the @newtype@ coercion from such a 'TyCon', which can be used to construct something
1243 -- with the @newtype@s type from its representation type (right hand side). If the supplied 'TyCon'
1244 -- is not a @newtype@, returns @Nothing@
1245 newTyConCo_maybe :: TyCon -> Maybe TyCon
1246 newTyConCo_maybe (AlgTyCon {algTcRhs = NewTyCon { nt_co = co }}) = co
1247 newTyConCo_maybe _ = Nothing
1249 -- | Find the primitive representation of a 'TyCon'
1250 tyConPrimRep :: TyCon -> PrimRep
1251 tyConPrimRep (PrimTyCon {primTyConRep = rep}) = rep
1252 tyConPrimRep tc = ASSERT(not (isUnboxedTupleTyCon tc)) PtrRep
1256 -- | Find the \"stupid theta\" of the 'TyCon'. A \"stupid theta\" is the context to the left of
1257 -- an algebraic type declaration, e.g. @Eq a@ in the declaration @data Eq a => T a ...@
1258 tyConStupidTheta :: TyCon -> [PredType]
1259 tyConStupidTheta (AlgTyCon {algTcStupidTheta = stupid}) = stupid
1260 tyConStupidTheta (TupleTyCon {}) = []
1261 tyConStupidTheta tycon = pprPanic "tyConStupidTheta" (ppr tycon)
1265 -- | Extract the 'TyVar's bound by a type synonym and the corresponding (unsubstituted) right hand side.
1266 -- If the given 'TyCon' is not a type synonym, panics
1267 synTyConDefn :: TyCon -> ([TyVar], Type)
1268 synTyConDefn (SynTyCon {tyConTyVars = tyvars, synTcRhs = SynonymTyCon ty})
1270 synTyConDefn tycon = pprPanic "getSynTyConDefn" (ppr tycon)
1272 -- | Extract the information pertaining to the right hand side of a type synonym (@type@) declaration. Panics
1273 -- if the given 'TyCon' is not a type synonym
1274 synTyConRhs :: TyCon -> SynTyConRhs
1275 synTyConRhs (SynTyCon {synTcRhs = rhs}) = rhs
1276 synTyConRhs tc = pprPanic "synTyConRhs" (ppr tc)
1278 -- | Find the expansion of the type synonym represented by the given 'TyCon'. The free variables of this
1279 -- type will typically include those 'TyVar's bound by the 'TyCon'. Panics if the 'TyCon' is not that of
1281 synTyConType :: TyCon -> Type
1282 synTyConType tc = case synTcRhs tc of
1284 _ -> pprPanic "synTyConType" (ppr tc)
1288 -- | If the given 'TyCon' has a /single/ data constructor, i.e. it is a @data@ type with one
1289 -- alternative, a tuple type or a @newtype@ then that constructor is returned. If the 'TyCon'
1290 -- has more than one constructor, or represents a primitive or function type constructor then
1291 -- @Nothing@ is returned. In any other case, the function panics
1292 tyConSingleDataCon_maybe :: TyCon -> Maybe DataCon
1293 tyConSingleDataCon_maybe (TupleTyCon {dataCon = c}) = Just c
1294 tyConSingleDataCon_maybe (AlgTyCon {algTcRhs = DataTyCon { data_cons = [c] }}) = Just c
1295 tyConSingleDataCon_maybe (AlgTyCon {algTcRhs = NewTyCon { data_con = c }}) = Just c
1296 tyConSingleDataCon_maybe _ = Nothing
1300 -- | Is this 'TyCon' that for a class instance?
1301 isClassTyCon :: TyCon -> Bool
1302 isClassTyCon (AlgTyCon {algTcParent = ClassTyCon _}) = True
1303 isClassTyCon _ = False
1305 -- | If this 'TyCon' is that for a class instance, return the class it is for.
1306 -- Otherwise returns @Nothing@
1307 tyConClass_maybe :: TyCon -> Maybe Class
1308 tyConClass_maybe (AlgTyCon {algTcParent = ClassTyCon clas}) = Just clas
1309 tyConClass_maybe _ = Nothing
1311 ----------------------------------------------------------------------------
1312 tyConParent :: TyCon -> TyConParent
1313 tyConParent (AlgTyCon {algTcParent = parent}) = parent
1314 tyConParent (SynTyCon {synTcParent = parent}) = parent
1315 tyConParent _ = NoParentTyCon
1317 -- | Is this 'TyCon' that for a family instance, be that for a synonym or an
1318 -- algebraic family instance?
1319 isFamInstTyCon :: TyCon -> Bool
1320 isFamInstTyCon tc = case tyConParent tc of
1321 FamInstTyCon {} -> True
1324 tyConFamInstSig_maybe :: TyCon -> Maybe (TyCon, [Type], TyCon)
1325 tyConFamInstSig_maybe tc
1326 = case tyConParent tc of
1327 FamInstTyCon f ts co_tc -> Just (f, ts, co_tc)
1330 -- | If this 'TyCon' is that of a family instance, return the family in question
1331 -- and the instance types. Otherwise, return @Nothing@
1332 tyConFamInst_maybe :: TyCon -> Maybe (TyCon, [Type])
1333 tyConFamInst_maybe tc
1334 = case tyConParent tc of
1335 FamInstTyCon f ts _ -> Just (f, ts)
1338 -- | If this 'TyCon' is that of a family instance, return a 'TyCon' which represents
1339 -- a coercion identifying the representation type with the type instance family.
1340 -- Otherwise, return @Nothing@
1341 tyConFamilyCoercion_maybe :: TyCon -> Maybe TyCon
1342 tyConFamilyCoercion_maybe tc
1343 = case tyConParent tc of
1344 FamInstTyCon _ _ co -> Just co
1349 %************************************************************************
1351 \subsection[TyCon-instances]{Instance declarations for @TyCon@}
1353 %************************************************************************
1355 @TyCon@s are compared by comparing their @Unique@s.
1357 The strictness analyser needs @Ord@. It is a lexicographic order with
1358 the property @(a<=b) || (b<=a)@.
1361 instance Eq TyCon where
1362 a == b = case (a `compare` b) of { EQ -> True; _ -> False }
1363 a /= b = case (a `compare` b) of { EQ -> False; _ -> True }
1365 instance Ord TyCon where
1366 a <= b = case (a `compare` b) of { LT -> True; EQ -> True; GT -> False }
1367 a < b = case (a `compare` b) of { LT -> True; EQ -> False; GT -> False }
1368 a >= b = case (a `compare` b) of { LT -> False; EQ -> True; GT -> True }
1369 a > b = case (a `compare` b) of { LT -> False; EQ -> False; GT -> True }
1370 compare a b = getUnique a `compare` getUnique b
1372 instance Uniquable TyCon where
1373 getUnique tc = tyConUnique tc
1375 instance Outputable CoTyConDesc where
1376 ppr CoSym = ptext (sLit "SYM")
1377 ppr CoTrans = ptext (sLit "TRANS")
1378 ppr CoLeft = ptext (sLit "LEFT")
1379 ppr CoRight = ptext (sLit "RIGHT")
1380 ppr CoCsel1 = ptext (sLit "CSEL1")
1381 ppr CoCsel2 = ptext (sLit "CSEL2")
1382 ppr CoCselR = ptext (sLit "CSELR")
1383 ppr CoInst = ptext (sLit "INST")
1384 ppr CoUnsafe = ptext (sLit "UNSAFE")
1385 ppr (CoAxiom {}) = ptext (sLit "AXIOM")
1387 instance Outputable TyCon where
1388 ppr tc = ppr (getName tc)
1390 instance NamedThing TyCon where
1393 instance Data.Typeable TyCon where
1394 typeOf _ = Data.mkTyConApp (Data.mkTyCon "TyCon") []
1396 instance Data.Data TyCon where
1398 toConstr _ = abstractConstr "TyCon"
1399 gunfold _ _ = error "gunfold"
1400 dataTypeOf _ = mkNoRepType "TyCon"