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"
added
removed
compiler/types/TyCon.lhs
