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
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 * In the future we might want to support
156 * closed type families (esp when we have proper kinds)
157 * injective type families (allow decomposition)
158 but we don't at the moment [2010]
160 Note [Data type families]
161 ~~~~~~~~~~~~~~~~~~~~~~~~~
162 See also Note [Wrappers for data instance tycons] in MkId.lhs
164 * Data type families are declared thus
166 data instance T Int = T1 | T2 Bool
168 Here T is the "family TyCon".
170 * Reply "yes" to isDataFamilyTyCon, and isFamilyTyCon
172 * The user does not see any "equivalent types" as he did with type
173 synonym families. He just sees constructors with types
177 * Here's the FC version of the above declarations:
180 data R:TInt = T1 | T2 Bool
181 axiom ax_ti : T Int ~ R:TInt
183 The R:TInt is the "representation TyCons".
184 It has an AlgTyConParent of
185 FamInstTyCon T [Int] ax_ti
187 * The data contructor T2 has a wrapper (which is what the
188 source-level "T2" invokes):
190 $WT2 :: Bool -> T Int
191 $WT2 b = T2 b `cast` sym ax_ti
193 * A data instance can declare a fully-fledged GADT:
195 data instance T (a,b) where
197 X2 :: a -> b -> T (a,b)
199 Here's the FC version of the above declaration:
202 X1 :: R:TPair Int Bool
203 X2 :: a -> b -> R:TPair a b
204 axiom ax_pr :: T (a,b) ~ R:TPair a b
206 $WX1 :: forall a b. a -> b -> T (a,b)
207 $WX1 a b (x::a) (y::b) = X2 a b x y `cast` sym (ax_pr a b)
209 The R:TPair are the "representation TyCons".
210 We have a bit of work to do, to unpick the result types of the
211 data instance declaration for T (a,b), to get the result type in the
212 representation; e.g. T (a,b) --> R:TPair a b
214 The representation TyCon R:TList, has an AlgTyConParent of
216 FamInstTyCon T [(a,b)] ax_pr
218 * Notice that T is NOT translated to a FC type function; it just
219 becomes a "data type" with no constructors, which can be coerced inot
220 into R:TInt, R:TPair by the axioms. These axioms
221 axioms come into play when (and *only* when) you
222 - use a data constructor
223 - do pattern matching
224 Rather like newtype, in fact
228 - T behaves just like a data type so far as decomposition is concerned
230 - (T Int) is not implicitly converted to R:TInt during type inference.
231 Indeed the latter type is unknown to the programmer.
233 - There *is* an instance for (T Int) in the type-family instance
234 environment, but it is only used for overlap checking
236 - It's fine to have T in the LHS of a type function:
237 type instance F (T a) = [a]
239 It was this last point that confused me! The big thing is that you
240 should not think of a data family T as a *type function* at all, not
241 even an injective one! We can't allow even injective type functions
242 on the LHS of a type function:
243 type family injective G a :: *
244 type instance F (G Int) = Bool
245 is no good, even if G is injective, because consider
246 type instance G Int = Bool
247 type instance F Bool = Char
249 So a data type family is not an injective type function. It's just a
250 data type with some axioms that connect it to other data types.
252 %************************************************************************
254 \subsection{The data type}
256 %************************************************************************
259 -- | TyCons represent type constructors. Type constructors are introduced by things such as:
261 -- 1) Data declarations: @data Foo = ...@ creates the @Foo@ type constructor of kind @*@
263 -- 2) Type synonyms: @type Foo = ...@ creates the @Foo@ type constructor
265 -- 3) Newtypes: @newtype Foo a = MkFoo ...@ creates the @Foo@ type constructor of kind @* -> *@
267 -- 4) Class declarations: @class Foo where@ creates the @Foo@ type constructor of kind @*@
269 -- 5) Type coercions! This is because we represent a coercion from @t1@ to @t2@
270 -- as a 'Type', where that type has kind @t1 ~ t2@. See "Coercion" for more on this
272 -- This data type also encodes a number of primitive, built in type constructors such as those
273 -- for function and tuple types.
275 = -- | The function type constructor, @(->)@
277 tyConUnique :: Unique,
283 -- | Algebraic type constructors, which are defined to be those
284 -- arising @data@ type and @newtype@ declarations. All these
285 -- constructors are lifted and boxed. See 'AlgTyConRhs' for more
288 tyConUnique :: Unique,
293 tyConTyVars :: [TyVar], -- ^ The type variables used in the type constructor.
294 -- Invariant: length tyvars = arity
295 -- Precisely, this list scopes over:
297 -- 1. The 'algTcStupidTheta'
298 -- 2. The cached types in 'algTyConRhs.NewTyCon'
299 -- 3. The family instance types if present
301 -- Note that it does /not/ scope over the data constructors.
303 algTcGadtSyntax :: Bool, -- ^ Was the data type declared with GADT syntax?
304 -- If so, that doesn't mean it's a true GADT;
305 -- only that the "where" form was used.
306 -- This field is used only to guide pretty-printing
308 algTcStupidTheta :: [PredType], -- ^ The \"stupid theta\" for the data type
309 -- (always empty for GADTs).
310 -- A \"stupid theta\" is the context to the left
311 -- of an algebraic type declaration,
312 -- e.g. @Eq a@ in the declaration
313 -- @data Eq a => T a ...@.
315 algTcRhs :: AlgTyConRhs, -- ^ Contains information about the
316 -- data constructors of the algebraic type
318 algTcRec :: RecFlag, -- ^ Tells us whether the data type is part
319 -- of a mutually-recursive group or not
321 hasGenerics :: Bool, -- ^ Whether generic (in the -XGenerics sense)
322 -- to\/from functions are available in the exports
323 -- of the data type's source module.
325 algTcParent :: TyConParent -- ^ Gives the class or family declaration 'TyCon'
326 -- for derived 'TyCon's representing class
327 -- or family instances, respectively.
328 -- See also 'synTcParent'
331 -- | Represents the infinite family of tuple type constructors,
332 -- @()@, @(a,b)@, @(# a, b #)@ etc.
334 tyConUnique :: Unique,
338 tyConBoxed :: Boxity,
339 tyConTyVars :: [TyVar],
340 dataCon :: DataCon, -- ^ Corresponding tuple data constructor
344 -- | Represents type synonyms
346 tyConUnique :: Unique,
351 tyConTyVars :: [TyVar], -- Bound tyvars
353 synTcRhs :: SynTyConRhs, -- ^ Contains information about the
354 -- expansion of the synonym
356 synTcParent :: TyConParent -- ^ Gives the family declaration 'TyCon'
357 -- of 'TyCon's representing family instances
361 -- | Primitive types; cannot be defined in Haskell. This includes
362 -- the usual suspects (such as @Int#@) as well as foreign-imported
365 tyConUnique :: Unique,
368 tyConArity :: Arity, -- SLPJ Oct06: I'm not sure what the significance
369 -- of the arity of a primtycon is!
371 primTyConRep :: PrimRep, -- ^ Many primitive tycons are unboxed, but some are
372 -- boxed (represented by pointers). This 'PrimRep'
373 -- holds that information.
374 -- Only relevant if tc_kind = *
376 isUnLifted :: Bool, -- ^ Most primitive tycons are unlifted
377 -- (may not contain bottom)
378 -- but foreign-imported ones may be lifted
380 tyConExtName :: Maybe FastString -- ^ @Just e@ for foreign-imported types,
381 -- holds the name of the imported thing
384 -- | Type coercions, such as @(~)@, @sym@, @trans@, @left@ and @right@.
385 -- INVARIANT: Coercion TyCons are always fully applied
386 -- But note that a CoTyCon can be *over*-saturated in a type.
387 -- E.g. (sym g1) Int will be represented as (TyConApp sym [g1,Int])
389 tyConUnique :: Unique,
392 coTcDesc :: CoTyConDesc
395 -- | Any types. Like tuples, this is a potentially-infinite family of TyCons
396 -- one for each distinct Kind. They have no values at all.
397 -- Because there are infinitely many of them (like tuples) they are
398 -- defined in GHC.Prim and have names like "Any(*->*)".
399 -- Their Unique is derived from the OccName.
400 -- See Note [Any types] in TysPrim
402 tyConUnique :: Unique,
404 tc_kind :: Kind -- Never = *; that is done via PrimTyCon
405 -- See Note [Any types] in TysPrim
408 -- | Super-kinds. These are "kinds-of-kinds" and are never seen in
409 -- Haskell source programs. There are only two super-kinds: TY (aka
410 -- "box"), which is the super-kind of kinds that construct types
411 -- eventually, and CO (aka "diamond"), which is the super-kind of
412 -- kinds that just represent coercions.
414 -- Super-kinds have no kind themselves, and have arity zero
416 tyConUnique :: Unique,
420 -- | Names of the fields in an algebraic record type
421 type FieldLabel = Name
423 -- | Represents right-hand-sides of 'TyCon's for algebraic types
426 -- | Says that we know nothing about this data type, except that
427 -- it's represented by a pointer. Used when we export a data type
428 -- abstractly into an .hi file.
431 -- | Represents an open type family without a fixed right hand
432 -- side. Additional instances can appear at any time.
434 -- These are introduced by either a top level declaration:
438 -- Or an associated data type declaration, within a class declaration:
440 -- > class C a b where
444 -- | Information about those 'TyCon's derived from a @data@
445 -- declaration. This includes data types with no constructors at
448 data_cons :: [DataCon],
449 -- ^ The data type constructors; can be empty if the user
450 -- declares the type to have no constructors
452 -- INVARIANT: Kept in order of increasing 'DataCon' tag
453 -- (see the tag assignment in DataCon.mkDataCon)
455 is_enum :: Bool -- ^ Cached value: is this an enumeration type?
456 -- See Note [Enumeration types]
459 -- | Information about those 'TyCon's derived from a @newtype@ declaration
461 data_con :: DataCon, -- ^ The unique constructor for the @newtype@.
462 -- It has no existentials
464 nt_rhs :: Type, -- ^ Cached value: the argument type of the constructor,
465 -- which is just the representation type of the 'TyCon'
466 -- (remember that @newtype@s do not exist at runtime
467 -- so need a different representation type).
469 -- The free 'TyVar's of this type are the 'tyConTyVars'
470 -- from the corresponding 'TyCon'
472 nt_etad_rhs :: ([TyVar], Type),
473 -- ^ Same as the 'nt_rhs', but this time eta-reduced.
474 -- Hence the list of 'TyVar's in this field may be
475 -- shorter than the declared arity of the 'TyCon'.
477 -- See Note [Newtype eta]
479 nt_co :: Maybe TyCon -- ^ A 'TyCon' (which is always a 'CoTyCon') that can
480 -- have a 'Coercion' extracted from it to create
481 -- the @newtype@ from the representation 'Type'.
483 -- This field is optional for non-recursive @newtype@s only.
485 -- See Note [Newtype coercions]
486 -- Invariant: arity = #tvs in nt_etad_rhs;
487 -- See Note [Newtype eta]
488 -- Watch out! If any newtypes become transparent
489 -- again check Trac #1072.
492 -- | Extract those 'DataCon's that we are able to learn about. Note
493 -- that visibility in this sense does not correspond to visibility in
494 -- the context of any particular user program!
495 visibleDataCons :: AlgTyConRhs -> [DataCon]
496 visibleDataCons AbstractTyCon = []
497 visibleDataCons DataFamilyTyCon {} = []
498 visibleDataCons (DataTyCon{ data_cons = cs }) = cs
499 visibleDataCons (NewTyCon{ data_con = c }) = [c]
501 -- ^ Both type classes as well as family instances imply implicit
502 -- type constructors. These implicit type constructors refer to their parent
503 -- structure (ie, the class or family from which they derive) using a type of
504 -- the following form. We use 'TyConParent' for both algebraic and synonym
505 -- types, but the variant 'ClassTyCon' will only be used by algebraic 'TyCon's.
507 = -- | An ordinary type constructor has no parent.
510 -- | Type constructors representing a class dictionary.
512 Class -- INVARIANT: the classTyCon of this Class is the current tycon
514 -- | An *associated* type of a class.
516 Class -- The class in whose declaration the family is declared
517 -- The 'tyConTyVars' of this 'TyCon' may mention some
518 -- of the same type variables as the classTyVars of the
519 -- parent 'Class'. E.g.
526 -- Here the 'a' is shared with the 'Class', and that is
527 -- important. In an instance declaration we expect the
528 -- two to be instantiated the same way. Eg.
531 -- instanc C [x] (Tree y) where
532 -- data T c [x] = T1 x | T2 c
535 -- | Type constructors representing an instance of a type family. Parameters:
537 -- 1) The type family in question
539 -- 2) Instance types; free variables are the 'tyConTyVars'
540 -- of the current 'TyCon' (not the family one). INVARIANT:
541 -- the number of types matches the arity of the family 'TyCon'
543 -- 3) A 'CoTyCon' identifying the representation
544 -- type with the type instance family
545 | FamInstTyCon -- See Note [Data type families]
546 -- and Note [Type synonym families]
547 TyCon -- The family TyCon
548 [Type] -- Argument types (mentions the tyConTyVars of this TyCon)
549 TyCon -- The coercion constructor
551 -- E.g. data intance T [a] = ...
552 -- gives a representation tycon:
553 -- data R:TList a = ...
554 -- axiom co a :: T [a] ~ R:TList a
555 -- with R:TList's algTcParent = FamInstTyCon T [a] co
557 -- | Checks the invariants of a 'TyConParent' given the appropriate type class name, if any
558 okParent :: Name -> TyConParent -> Bool
559 okParent _ NoParentTyCon = True
560 okParent tc_name (AssocFamilyTyCon cls) = tc_name `elem` map tyConName (classATs cls)
561 okParent tc_name (ClassTyCon cls) = tc_name == tyConName (classTyCon cls)
562 okParent _ (FamInstTyCon fam_tc tys _co_tc) = tyConArity fam_tc == length tys
564 isNoParent :: TyConParent -> Bool
565 isNoParent NoParentTyCon = True
570 -- | Information pertaining to the expansion of a type synonym (@type@)
572 = -- | An ordinary type synonyn.
574 Type -- This 'Type' is the rhs, and may mention from 'tyConTyVars'.
575 -- It acts as a template for the expansion when the 'TyCon'
576 -- is applied to some types.
578 -- | A type synonym family e.g. @type family F x y :: * -> *@
585 | CoCsel1 | CoCsel2 | CoCselR
588 | CoAxiom -- C tvs : F lhs-tys ~ rhs-ty
589 { co_ax_tvs :: [TyVar]
591 , co_ax_rhs :: Type }
596 Note [Enumeration types]
597 ~~~~~~~~~~~~~~~~~~~~~~~~
598 We define datatypes with no constructors to *not* be
599 enumerations; this fixes trac #2578, Otherwise we
600 end up generating an empty table for
601 <mod>_<type>_closure_tbl
602 which is used by tagToEnum# to map Int# to constructors
603 in an enumeration. The empty table apparently upset
606 Moreover, all the data constructor must be enumerations, meaning
607 they have type (forall abc. T a b c). GADTs are not enumerations.
613 What would [T1 ..] be? [T1,T3] :: T Int? Easiest thing is to exclude them.
616 Note [Newtype coercions]
617 ~~~~~~~~~~~~~~~~~~~~~~~~
618 The NewTyCon field nt_co is a a TyCon (a coercion constructor in fact)
619 which is used for coercing from the representation type of the
620 newtype, to the newtype itself. For example,
622 newtype T a = MkT (a -> a)
624 the NewTyCon for T will contain nt_co = CoT where CoT t : T t ~ t ->
625 t. This TyCon is a CoTyCon, so it does not have a kind on its
626 own; it basically has its own typing rule for the fully-applied
627 version. If the newtype T has k type variables then CoT has arity at
628 most k. In the case that the right hand side is a type application
629 ending with the same type variables as the left hand side, we
630 "eta-contract" the coercion. So if we had
632 newtype S a = MkT [a]
634 then we would generate the arity 0 coercion CoS : S ~ []. The
635 primary reason we do this is to make newtype deriving cleaner.
637 In the paper we'd write
638 axiom CoT : (forall t. T t) ~ (forall t. [t])
639 and then when we used CoT at a particular type, s, we'd say
641 which encodes as (TyConApp instCoercionTyCon [TyConApp CoT [], s])
643 But in GHC we instead make CoT into a new piece of type syntax, CoTyCon,
644 (like instCoercionTyCon, symCoercionTyCon etc), which must always
645 be saturated, but which encodes as
647 In the vocabulary of the paper it's as if we had axiom declarations
649 axiom CoT t : T t ~ [t]
654 newtype Parser m a = MkParser (Foogle m a)
655 Are these two types equal (to Core)?
658 Well, yes. But to see that easily we eta-reduce the RHS type of
659 Parser, in this case to ([], Froogle), so that even unsaturated applications
660 of Parser will work right. This eta reduction is done when the type
661 constructor is built, and cached in NewTyCon. The cached field is
662 only used in coreExpandTyCon_maybe.
664 Here's an example that I think showed up in practice
666 newtype T a = MkT [a]
667 newtype Foo m = MkFoo (forall a. m a -> Int)
673 w2 = MkFoo (\(MkT x) -> case w1 of MkFoo f -> f x)
675 After desugaring, and discarding the data constructors for the newtypes,
679 And now Lint complains unless Foo T == Foo [], and that requires T==[]
681 This point carries over to the newtype coercion, because we need to
683 w2 = w1 `cast` Foo CoT
685 so the coercion tycon CoT must have
690 %************************************************************************
694 %************************************************************************
696 A PrimRep is somewhat similar to a CgRep (see codeGen/SMRep) and a
697 MachRep (see cmm/CmmExpr), although each of these types has a distinct
698 and clearly defined purpose:
700 - A PrimRep is a CgRep + information about signedness + information
701 about primitive pointers (AddrRep). Signedness and primitive
702 pointers are required when passing a primitive type to a foreign
703 function, but aren't needed for call/return conventions of Haskell
706 - A MachRep is a basic machine type (non-void, doesn't contain
707 information on pointerhood or signedness, but contains some
708 reps that don't have corresponding Haskell types).
711 -- | A 'PrimRep' is an abstraction of a type. It contains information that
712 -- the code generator needs in order to pass arguments, return results,
713 -- and store values of this type.
717 | IntRep -- ^ Signed, word-sized value
718 | WordRep -- ^ Unsigned, word-sized value
719 | Int64Rep -- ^ Signed, 64 bit value (with 32-bit words only)
720 | Word64Rep -- ^ Unsigned, 64 bit value (with 32-bit words only)
721 | AddrRep -- ^ A pointer, but /not/ to a Haskell value (use 'PtrRep')
726 instance Outputable PrimRep where
727 ppr r = text (show r)
729 -- | Find the size of a 'PrimRep', in words
730 primRepSizeW :: PrimRep -> Int
731 primRepSizeW IntRep = 1
732 primRepSizeW WordRep = 1
733 primRepSizeW Int64Rep = wORD64_SIZE `quot` wORD_SIZE
734 primRepSizeW Word64Rep= wORD64_SIZE `quot` wORD_SIZE
735 primRepSizeW FloatRep = 1 -- NB. might not take a full word
736 primRepSizeW DoubleRep= dOUBLE_SIZE `quot` wORD_SIZE
737 primRepSizeW AddrRep = 1
738 primRepSizeW PtrRep = 1
739 primRepSizeW VoidRep = 0
742 %************************************************************************
744 \subsection{TyCon Construction}
746 %************************************************************************
748 Note: the TyCon constructors all take a Kind as one argument, even though
749 they could, in principle, work out their Kind from their other arguments.
750 But to do so they need functions from Types, and that makes a nasty
751 module mutual-recursion. And they aren't called from many places.
752 So we compromise, and move their Kind calculation to the call site.
755 -- | Given the name of the function type constructor and it's kind, create the
756 -- corresponding 'TyCon'. It is reccomended to use 'TypeRep.funTyCon' if you want
757 -- this functionality
758 mkFunTyCon :: Name -> Kind -> TyCon
761 tyConUnique = nameUnique name,
767 -- | This is the making of an algebraic 'TyCon'. Notably, you have to
768 -- pass in the generic (in the -XGenerics sense) information about the
769 -- type constructor - you can get hold of it easily (see Generics
772 -> Kind -- ^ Kind of the resulting 'TyCon'
773 -> [TyVar] -- ^ 'TyVar's scoped over: see 'tyConTyVars'.
774 -- Arity is inferred from the length of this list
775 -> [PredType] -- ^ Stupid theta: see 'algTcStupidTheta'
776 -> AlgTyConRhs -- ^ Information about dat aconstructors
778 -> RecFlag -- ^ Is the 'TyCon' recursive?
779 -> Bool -- ^ Does it have generic functions? See 'hasGenerics'
780 -> Bool -- ^ Was the 'TyCon' declared with GADT syntax?
782 mkAlgTyCon name kind tyvars stupid rhs parent is_rec gen_info gadt_syn
785 tyConUnique = nameUnique name,
787 tyConArity = length tyvars,
788 tyConTyVars = tyvars,
789 algTcStupidTheta = stupid,
791 algTcParent = ASSERT( okParent name parent ) parent,
793 algTcGadtSyntax = gadt_syn,
794 hasGenerics = gen_info
797 -- | Simpler specialization of 'mkAlgTyCon' for classes
798 mkClassTyCon :: Name -> Kind -> [TyVar] -> AlgTyConRhs -> Class -> RecFlag -> TyCon
799 mkClassTyCon name kind tyvars rhs clas is_rec =
800 mkAlgTyCon name kind tyvars [] rhs (ClassTyCon clas) is_rec False False
803 -> Kind -- ^ Kind of the resulting 'TyCon'
804 -> Arity -- ^ Arity of the tuple
805 -> [TyVar] -- ^ 'TyVar's scoped over: see 'tyConTyVars'
807 -> Boxity -- ^ Whether the tuple is boxed or unboxed
808 -> Bool -- ^ Does it have generic functions? See 'hasGenerics'
810 mkTupleTyCon name kind arity tyvars con boxed gen_info
812 tyConUnique = nameUnique name,
817 tyConTyVars = tyvars,
819 hasGenerics = gen_info
822 -- ^ Foreign-imported (.NET) type constructors are represented
823 -- as primitive, but /lifted/, 'TyCons' for now. They are lifted
824 -- because the Haskell type @T@ representing the (foreign) .NET
825 -- type @T@ is actually implemented (in ILX) as a @thunk<T>@
826 mkForeignTyCon :: Name
827 -> Maybe FastString -- ^ Name of the foreign imported thing, maybe
831 mkForeignTyCon name ext_name kind arity
834 tyConUnique = nameUnique name,
837 primTyConRep = PtrRep, -- they all do
839 tyConExtName = ext_name
843 -- | Create an unlifted primitive 'TyCon', such as @Int#@
844 mkPrimTyCon :: Name -> Kind -> Arity -> PrimRep -> TyCon
845 mkPrimTyCon name kind arity rep
846 = mkPrimTyCon' name kind arity rep True
848 -- | Kind constructors
849 mkKindTyCon :: Name -> Kind -> TyCon
850 mkKindTyCon name kind
851 = mkPrimTyCon' name kind 0 VoidRep True
853 -- | Create a lifted primitive 'TyCon' such as @RealWorld@
854 mkLiftedPrimTyCon :: Name -> Kind -> Arity -> PrimRep -> TyCon
855 mkLiftedPrimTyCon name kind arity rep
856 = mkPrimTyCon' name kind arity rep False
858 mkPrimTyCon' :: Name -> Kind -> Arity -> PrimRep -> Bool -> TyCon
859 mkPrimTyCon' name kind arity rep is_unlifted
862 tyConUnique = nameUnique name,
866 isUnLifted = is_unlifted,
867 tyConExtName = Nothing
870 -- | Create a type synonym 'TyCon'
871 mkSynTyCon :: Name -> Kind -> [TyVar] -> SynTyConRhs -> TyConParent -> TyCon
872 mkSynTyCon name kind tyvars rhs parent
875 tyConUnique = nameUnique name,
877 tyConArity = length tyvars,
878 tyConTyVars = tyvars,
883 -- | Create a coercion 'TyCon'
884 mkCoercionTyCon :: Name -> Arity
887 mkCoercionTyCon name arity desc
890 tyConUnique = nameUnique name,
894 mkAnyTyCon :: Name -> Kind -> TyCon
896 = AnyTyCon { tyConName = name,
898 tyConUnique = nameUnique name }
900 -- | Create a super-kind 'TyCon'
901 mkSuperKindTyCon :: Name -> TyCon -- Super kinds always have arity zero
902 mkSuperKindTyCon name
905 tyConUnique = nameUnique name
910 isFunTyCon :: TyCon -> Bool
911 isFunTyCon (FunTyCon {}) = True
914 -- | Test if the 'TyCon' is algebraic but abstract (invisible data constructors)
915 isAbstractTyCon :: TyCon -> Bool
916 isAbstractTyCon (AlgTyCon { algTcRhs = AbstractTyCon }) = True
917 isAbstractTyCon _ = False
919 -- | Make an algebraic 'TyCon' abstract. Panics if the supplied 'TyCon' is not algebraic
920 makeTyConAbstract :: TyCon -> TyCon
921 makeTyConAbstract tc@(AlgTyCon {}) = tc { algTcRhs = AbstractTyCon }
922 makeTyConAbstract tc = pprPanic "makeTyConAbstract" (ppr tc)
924 -- | Does this 'TyCon' represent something that cannot be defined in Haskell?
925 isPrimTyCon :: TyCon -> Bool
926 isPrimTyCon (PrimTyCon {}) = True
927 isPrimTyCon _ = False
929 -- | Is this 'TyCon' unlifted (i.e. cannot contain bottom)? Note that this can only
930 -- be true for primitive and unboxed-tuple 'TyCon's
931 isUnLiftedTyCon :: TyCon -> Bool
932 isUnLiftedTyCon (PrimTyCon {isUnLifted = is_unlifted}) = is_unlifted
933 isUnLiftedTyCon (TupleTyCon {tyConBoxed = boxity}) = not (isBoxed boxity)
934 isUnLiftedTyCon _ = False
936 -- | Returns @True@ if the supplied 'TyCon' resulted from either a
937 -- @data@ or @newtype@ declaration
938 isAlgTyCon :: TyCon -> Bool
939 isAlgTyCon (AlgTyCon {}) = True
940 isAlgTyCon (TupleTyCon {}) = True
943 isDataTyCon :: TyCon -> Bool
944 -- ^ Returns @True@ for data types that are /definitely/ represented by
945 -- heap-allocated constructors. These are scrutinised by Core-level
946 -- @case@ expressions, and they get info tables allocated for them.
948 -- Generally, the function will be true for all @data@ types and false
949 -- for @newtype@s, unboxed tuples and type family 'TyCon's. But it is
950 -- not guarenteed to return @True@ in all cases that it could.
952 -- NB: for a data type family, only the /instance/ 'TyCon's
953 -- get an info table. The family declaration 'TyCon' does not
954 isDataTyCon (AlgTyCon {algTcRhs = rhs})
956 DataFamilyTyCon {} -> False
959 AbstractTyCon -> False -- We don't know, so return False
960 isDataTyCon (TupleTyCon {tyConBoxed = boxity}) = isBoxed boxity
961 isDataTyCon _ = False
963 -- | Is this 'TyCon' that for a @newtype@
964 isNewTyCon :: TyCon -> Bool
965 isNewTyCon (AlgTyCon {algTcRhs = NewTyCon {}}) = True
968 -- | Take a 'TyCon' apart into the 'TyVar's it scopes over, the 'Type' it expands
969 -- into, and (possibly) a coercion from the representation type to the @newtype@.
970 -- Returns @Nothing@ if this is not possible.
971 unwrapNewTyCon_maybe :: TyCon -> Maybe ([TyVar], Type, Maybe TyCon)
972 unwrapNewTyCon_maybe (AlgTyCon { tyConTyVars = tvs,
973 algTcRhs = NewTyCon { nt_co = mb_co,
975 = Just (tvs, rhs, mb_co)
976 unwrapNewTyCon_maybe _ = Nothing
978 isProductTyCon :: TyCon -> Bool
979 -- | A /product/ 'TyCon' must both:
981 -- 1. Have /one/ constructor
983 -- 2. /Not/ be existential
985 -- However other than this there are few restrictions: they may be @data@ or @newtype@
986 -- 'TyCon's of any boxity and may even be recursive.
987 isProductTyCon tc@(AlgTyCon {}) = case algTcRhs tc of
988 DataTyCon{ data_cons = [data_con] }
989 -> isVanillaDataCon data_con
992 isProductTyCon (TupleTyCon {}) = True
993 isProductTyCon _ = False
995 -- | Is this a 'TyCon' representing a type synonym (@type@)?
996 isSynTyCon :: TyCon -> Bool
997 isSynTyCon (SynTyCon {}) = True
1000 -- As for newtypes, it is in some contexts important to distinguish between
1001 -- closed synonyms and synonym families, as synonym families have no unique
1002 -- right hand side to which a synonym family application can expand.
1005 isDecomposableTyCon :: TyCon -> Bool
1006 -- True iff we can decompose (T a b c) into ((T a b) c)
1007 -- Specifically NOT true of synonyms (open and otherwise) and coercions
1008 isDecomposableTyCon (SynTyCon {}) = False
1009 isDecomposableTyCon (CoTyCon {}) = 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 -- | Attempt to pull a 'TyCon' apart into the arity and 'coKindFun' of
1117 -- a coercion 'TyCon'. Returns @Nothing@ if the 'TyCon' is not of the
1119 isCoercionTyCon_maybe :: TyCon -> Maybe (Arity, CoTyConDesc)
1120 isCoercionTyCon_maybe (CoTyCon {tyConArity = ar, coTcDesc = desc})
1122 isCoercionTyCon_maybe _ = Nothing
1124 -- | Is this a 'TyCon' that represents a coercion?
1125 isCoercionTyCon :: TyCon -> Bool
1126 isCoercionTyCon (CoTyCon {}) = True
1127 isCoercionTyCon _ = False
1129 -- | Identifies implicit tycons that, in particular, do not go into interface
1130 -- files (because they are implicitly reconstructed when the interface is
1135 -- * Associated families are implicit, as they are re-constructed from
1136 -- the class declaration in which they reside, and
1138 -- * Family instances are /not/ implicit as they represent the instance body
1139 -- (similar to a @dfun@ does that for a class instance).
1140 isImplicitTyCon :: TyCon -> Bool
1141 isImplicitTyCon tycon | isTyConAssoc tycon = True
1142 | isSynTyCon tycon = False
1143 | isAlgTyCon tycon = isClassTyCon tycon ||
1145 isImplicitTyCon _other = True
1146 -- catches: FunTyCon, PrimTyCon,
1147 -- CoTyCon, SuperKindTyCon
1151 -----------------------------------------------
1152 -- Expand type-constructor applications
1153 -----------------------------------------------
1156 tcExpandTyCon_maybe, coreExpandTyCon_maybe
1158 -> [Type] -- ^ Arguments to 'TyCon'
1159 -> Maybe ([(TyVar,Type)],
1161 [Type]) -- ^ Returns a 'TyVar' substitution, the body type
1162 -- of the synonym (not yet substituted) and any arguments
1163 -- remaining from the application
1165 -- ^ Used to create the view the /typechecker/ has on 'TyCon's. We expand (closed) synonyms only, cf. 'coreExpandTyCon_maybe'
1166 tcExpandTyCon_maybe (SynTyCon {tyConTyVars = tvs,
1167 synTcRhs = SynonymTyCon rhs }) tys
1168 = expand tvs rhs tys
1169 tcExpandTyCon_maybe _ _ = Nothing
1173 -- ^ Used to create the view /Core/ has on 'TyCon's. We expand not only closed synonyms like 'tcExpandTyCon_maybe',
1174 -- but also non-recursive @newtype@s
1175 coreExpandTyCon_maybe (AlgTyCon {
1176 algTcRhs = NewTyCon { nt_etad_rhs = etad_rhs, nt_co = Nothing }}) tys
1177 = case etad_rhs of -- Don't do this in the pattern match, lest we accidentally
1178 -- match the etad_rhs of a *recursive* newtype
1179 (tvs,rhs) -> expand tvs rhs tys
1181 coreExpandTyCon_maybe tycon tys = tcExpandTyCon_maybe tycon tys
1185 expand :: [TyVar] -> Type -- Template
1187 -> Maybe ([(TyVar,Type)], Type, [Type]) -- Expansion
1189 = case n_tvs `compare` length tys of
1190 LT -> Just (tvs `zip` tys, rhs, drop n_tvs tys)
1191 EQ -> Just (tvs `zip` tys, rhs, [])
1198 -- | Does this 'TyCon' have any generic to\/from functions available? See also 'hasGenerics'
1199 tyConHasGenerics :: TyCon -> Bool
1200 tyConHasGenerics (AlgTyCon {hasGenerics = hg}) = hg
1201 tyConHasGenerics (TupleTyCon {hasGenerics = hg}) = hg
1202 tyConHasGenerics _ = False -- Synonyms
1204 tyConKind :: TyCon -> Kind
1205 tyConKind (FunTyCon { tc_kind = k }) = k
1206 tyConKind (AlgTyCon { tc_kind = k }) = k
1207 tyConKind (TupleTyCon { tc_kind = k }) = k
1208 tyConKind (SynTyCon { tc_kind = k }) = k
1209 tyConKind (PrimTyCon { tc_kind = k }) = k
1210 tyConKind (AnyTyCon { tc_kind = k }) = k
1211 tyConKind tc = pprPanic "tyConKind" (ppr tc) -- SuperKindTyCon and CoTyCon
1213 tyConHasKind :: TyCon -> Bool
1214 tyConHasKind (SuperKindTyCon {}) = False
1215 tyConHasKind (CoTyCon {}) = False
1216 tyConHasKind _ = True
1218 -- | As 'tyConDataCons_maybe', but returns the empty list of constructors if no constructors
1220 tyConDataCons :: TyCon -> [DataCon]
1221 -- It's convenient for tyConDataCons to return the
1222 -- empty list for type synonyms etc
1223 tyConDataCons tycon = tyConDataCons_maybe tycon `orElse` []
1225 -- | Determine the 'DataCon's originating from the given 'TyCon', if the 'TyCon' is the
1226 -- sort that can have any constructors (note: this does not include abstract algebraic types)
1227 tyConDataCons_maybe :: TyCon -> Maybe [DataCon]
1228 tyConDataCons_maybe (AlgTyCon {algTcRhs = DataTyCon { data_cons = cons }}) = Just cons
1229 tyConDataCons_maybe (AlgTyCon {algTcRhs = NewTyCon { data_con = con }}) = Just [con]
1230 tyConDataCons_maybe (TupleTyCon {dataCon = con}) = Just [con]
1231 tyConDataCons_maybe _ = Nothing
1233 -- | Determine the number of value constructors a 'TyCon' has. Panics if the 'TyCon'
1234 -- is not algebraic or a tuple
1235 tyConFamilySize :: TyCon -> Int
1236 tyConFamilySize (AlgTyCon {algTcRhs = DataTyCon {data_cons = cons}}) =
1238 tyConFamilySize (AlgTyCon {algTcRhs = NewTyCon {}}) = 1
1239 tyConFamilySize (AlgTyCon {algTcRhs = DataFamilyTyCon {}}) = 0
1240 tyConFamilySize (TupleTyCon {}) = 1
1241 tyConFamilySize other = pprPanic "tyConFamilySize:" (ppr other)
1243 -- | Extract an 'AlgTyConRhs' with information about data constructors from an algebraic or tuple
1244 -- 'TyCon'. Panics for any other sort of 'TyCon'
1245 algTyConRhs :: TyCon -> AlgTyConRhs
1246 algTyConRhs (AlgTyCon {algTcRhs = rhs}) = rhs
1247 algTyConRhs (TupleTyCon {dataCon = con, tyConArity = arity})
1248 = DataTyCon { data_cons = [con], is_enum = arity == 0 }
1249 algTyConRhs other = pprPanic "algTyConRhs" (ppr other)
1253 -- | Extract the bound type variables and type expansion of a type synonym 'TyCon'. Panics if the
1254 -- 'TyCon' is not a synonym
1255 newTyConRhs :: TyCon -> ([TyVar], Type)
1256 newTyConRhs (AlgTyCon {tyConTyVars = tvs, algTcRhs = NewTyCon { nt_rhs = rhs }}) = (tvs, rhs)
1257 newTyConRhs tycon = pprPanic "newTyConRhs" (ppr tycon)
1259 -- | Extract the bound type variables and type expansion of an eta-contracted type synonym 'TyCon'.
1260 -- Panics if the 'TyCon' is not a synonym
1261 newTyConEtadRhs :: TyCon -> ([TyVar], Type)
1262 newTyConEtadRhs (AlgTyCon {algTcRhs = NewTyCon { nt_etad_rhs = tvs_rhs }}) = tvs_rhs
1263 newTyConEtadRhs tycon = pprPanic "newTyConEtadRhs" (ppr tycon)
1265 -- | Extracts the @newtype@ coercion from such a 'TyCon', which can be used to construct something
1266 -- with the @newtype@s type from its representation type (right hand side). If the supplied 'TyCon'
1267 -- is not a @newtype@, returns @Nothing@
1268 newTyConCo_maybe :: TyCon -> Maybe TyCon
1269 newTyConCo_maybe (AlgTyCon {algTcRhs = NewTyCon { nt_co = co }}) = co
1270 newTyConCo_maybe _ = Nothing
1272 -- | Find the primitive representation of a 'TyCon'
1273 tyConPrimRep :: TyCon -> PrimRep
1274 tyConPrimRep (PrimTyCon {primTyConRep = rep}) = rep
1275 tyConPrimRep tc = ASSERT(not (isUnboxedTupleTyCon tc)) PtrRep
1279 -- | Find the \"stupid theta\" of the 'TyCon'. A \"stupid theta\" is the context to the left of
1280 -- an algebraic type declaration, e.g. @Eq a@ in the declaration @data Eq a => T a ...@
1281 tyConStupidTheta :: TyCon -> [PredType]
1282 tyConStupidTheta (AlgTyCon {algTcStupidTheta = stupid}) = stupid
1283 tyConStupidTheta (TupleTyCon {}) = []
1284 tyConStupidTheta tycon = pprPanic "tyConStupidTheta" (ppr tycon)
1288 -- | Extract the 'TyVar's bound by a type synonym and the corresponding (unsubstituted) right hand side.
1289 -- If the given 'TyCon' is not a type synonym, panics
1290 synTyConDefn :: TyCon -> ([TyVar], Type)
1291 synTyConDefn (SynTyCon {tyConTyVars = tyvars, synTcRhs = SynonymTyCon ty})
1293 synTyConDefn tycon = pprPanic "getSynTyConDefn" (ppr tycon)
1295 -- | Extract the information pertaining to the right hand side of a type synonym (@type@) declaration. Panics
1296 -- if the given 'TyCon' is not a type synonym
1297 synTyConRhs :: TyCon -> SynTyConRhs
1298 synTyConRhs (SynTyCon {synTcRhs = rhs}) = rhs
1299 synTyConRhs tc = pprPanic "synTyConRhs" (ppr tc)
1301 -- | Find the expansion of the type synonym represented by the given 'TyCon'. The free variables of this
1302 -- type will typically include those 'TyVar's bound by the 'TyCon'. Panics if the 'TyCon' is not that of
1304 synTyConType :: TyCon -> Type
1305 synTyConType tc = case synTcRhs tc of
1307 _ -> pprPanic "synTyConType" (ppr tc)
1311 -- | If the given 'TyCon' has a /single/ data constructor, i.e. it is a @data@ type with one
1312 -- alternative, a tuple type or a @newtype@ then that constructor is returned. If the 'TyCon'
1313 -- has more than one constructor, or represents a primitive or function type constructor then
1314 -- @Nothing@ is returned. In any other case, the function panics
1315 tyConSingleDataCon_maybe :: TyCon -> Maybe DataCon
1316 tyConSingleDataCon_maybe (TupleTyCon {dataCon = c}) = Just c
1317 tyConSingleDataCon_maybe (AlgTyCon {algTcRhs = DataTyCon { data_cons = [c] }}) = Just c
1318 tyConSingleDataCon_maybe (AlgTyCon {algTcRhs = NewTyCon { data_con = c }}) = Just c
1319 tyConSingleDataCon_maybe _ = Nothing
1323 -- | Is this 'TyCon' that for a class instance?
1324 isClassTyCon :: TyCon -> Bool
1325 isClassTyCon (AlgTyCon {algTcParent = ClassTyCon _}) = True
1326 isClassTyCon _ = False
1328 -- | If this 'TyCon' is that for a class instance, return the class it is for.
1329 -- Otherwise returns @Nothing@
1330 tyConClass_maybe :: TyCon -> Maybe Class
1331 tyConClass_maybe (AlgTyCon {algTcParent = ClassTyCon clas}) = Just clas
1332 tyConClass_maybe _ = Nothing
1334 ----------------------------------------------------------------------------
1335 tyConParent :: TyCon -> TyConParent
1336 tyConParent (AlgTyCon {algTcParent = parent}) = parent
1337 tyConParent (SynTyCon {synTcParent = parent}) = parent
1338 tyConParent _ = NoParentTyCon
1340 -- | Is this 'TyCon' that for a family instance, be that for a synonym or an
1341 -- algebraic family instance?
1342 isFamInstTyCon :: TyCon -> Bool
1343 isFamInstTyCon tc = case tyConParent tc of
1344 FamInstTyCon {} -> True
1347 tyConFamInstSig_maybe :: TyCon -> Maybe (TyCon, [Type], TyCon)
1348 tyConFamInstSig_maybe tc
1349 = case tyConParent tc of
1350 FamInstTyCon f ts co_tc -> Just (f, ts, co_tc)
1353 -- | If this 'TyCon' is that of a family instance, return the family in question
1354 -- and the instance types. Otherwise, return @Nothing@
1355 tyConFamInst_maybe :: TyCon -> Maybe (TyCon, [Type])
1356 tyConFamInst_maybe tc
1357 = case tyConParent tc of
1358 FamInstTyCon f ts _ -> Just (f, ts)
1361 -- | If this 'TyCon' is that of a family instance, return a 'TyCon' which represents
1362 -- a coercion identifying the representation type with the type instance family.
1363 -- Otherwise, return @Nothing@
1364 tyConFamilyCoercion_maybe :: TyCon -> Maybe TyCon
1365 tyConFamilyCoercion_maybe tc
1366 = case tyConParent tc of
1367 FamInstTyCon _ _ co -> Just co
1372 %************************************************************************
1374 \subsection[TyCon-instances]{Instance declarations for @TyCon@}
1376 %************************************************************************
1378 @TyCon@s are compared by comparing their @Unique@s.
1380 The strictness analyser needs @Ord@. It is a lexicographic order with
1381 the property @(a<=b) || (b<=a)@.
1384 instance Eq TyCon where
1385 a == b = case (a `compare` b) of { EQ -> True; _ -> False }
1386 a /= b = case (a `compare` b) of { EQ -> False; _ -> True }
1388 instance Ord TyCon where
1389 a <= b = case (a `compare` b) of { LT -> True; EQ -> True; GT -> False }
1390 a < b = case (a `compare` b) of { LT -> True; EQ -> False; GT -> False }
1391 a >= b = case (a `compare` b) of { LT -> False; EQ -> True; GT -> True }
1392 a > b = case (a `compare` b) of { LT -> False; EQ -> False; GT -> True }
1393 compare a b = getUnique a `compare` getUnique b
1395 instance Uniquable TyCon where
1396 getUnique tc = tyConUnique tc
1398 instance Outputable CoTyConDesc where
1399 ppr CoSym = ptext (sLit "SYM")
1400 ppr CoTrans = ptext (sLit "TRANS")
1401 ppr CoLeft = ptext (sLit "LEFT")
1402 ppr CoRight = ptext (sLit "RIGHT")
1403 ppr CoCsel1 = ptext (sLit "CSEL1")
1404 ppr CoCsel2 = ptext (sLit "CSEL2")
1405 ppr CoCselR = ptext (sLit "CSELR")
1406 ppr CoInst = ptext (sLit "INST")
1407 ppr CoUnsafe = ptext (sLit "UNSAFE")
1408 ppr (CoAxiom {}) = ptext (sLit "AXIOM")
1410 instance Outputable TyCon where
1411 ppr tc = ppr (getName tc)
1413 instance NamedThing TyCon where
1416 instance Data.Typeable TyCon where
1417 typeOf _ = Data.mkTyConApp (Data.mkTyCon "TyCon") []
1419 instance Data.Data TyCon where
1421 toConstr _ = abstractConstr "TyCon"
1422 gunfold _ _ = error "gunfold"
1423 dataTypeOf _ = mkNoRepType "TyCon"