X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2Ftypes%2FTyCon.lhs;h=dc7e2d3e327caff4534d6a10572fd045ebfe9a83;hp=fcd32c6974bce5bed8fb4cfca1ed0574daa1e0c6;hb=59fa6266f00b6edcfc20c491c8de9a1b215dfa22;hpb=0065d5ab628975892cea1ec7303f968c3338cbe1 diff --git a/compiler/types/TyCon.lhs b/compiler/types/TyCon.lhs index fcd32c6..dc7e2d3 100644 --- a/compiler/types/TyCon.lhs +++ b/compiler/types/TyCon.lhs @@ -1,75 +1,98 @@ % +% (c) The University of Glasgow 2006 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998 % -\section[TyCon]{The @TyCon@ datatype} + +The @TyCon@ datatype \begin{code} module TyCon( - TyCon, ArgVrcs, FieldLabel, - - PrimRep(..), - tyConPrimRep, - - AlgTyConRhs(..), visibleDataCons, - - isFunTyCon, isUnLiftedTyCon, isProductTyCon, - isAlgTyCon, isDataTyCon, isSynTyCon, isNewTyCon, isPrimTyCon, - isEnumerationTyCon, - isTupleTyCon, isUnboxedTupleTyCon, isBoxedTupleTyCon, tupleTyConBoxity, - isRecursiveTyCon, newTyConRep, newTyConRhs, - isHiBootTyCon, + -- * Main TyCon data types + TyCon, FieldLabel, - tcExpandTyCon_maybe, coreExpandTyCon_maybe, - - makeTyConAbstract, isAbstractTyCon, - - mkForeignTyCon, isForeignTyCon, + AlgTyConRhs(..), visibleDataCons, + TyConParent(..), + SynTyConRhs(..), + AssocFamilyPermutation, + -- ** Constructing TyCons mkAlgTyCon, mkClassTyCon, mkFunTyCon, mkPrimTyCon, + mkVoidPrimTyCon, mkLiftedPrimTyCon, mkTupleTyCon, mkSynTyCon, + mkSuperKindTyCon, + mkCoercionTyCon, + mkForeignTyCon, + + -- ** Predicates on TyCons + isAlgTyCon, + isClassTyCon, isFamInstTyCon, + isFunTyCon, + isPrimTyCon, + isTupleTyCon, isUnboxedTupleTyCon, isBoxedTupleTyCon, + isSynTyCon, isClosedSynTyCon, isOpenSynTyCon, + isSuperKindTyCon, + isCoercionTyCon, isCoercionTyCon_maybe, + isForeignTyCon, + + isDataTyCon, isProductTyCon, isEnumerationTyCon, + isNewTyCon, isAbstractTyCon, isOpenTyCon, + isUnLiftedTyCon, + isGadtSyntaxTyCon, + isTyConAssoc, + isRecursiveTyCon, + isHiBootTyCon, + isImplicitTyCon, tyConHasGenerics, + -- ** Extracting information out of TyCons tyConName, tyConKind, tyConUnique, tyConTyVars, - tyConArgVrcs, - algTyConRhs, tyConDataCons, tyConDataCons_maybe, tyConFamilySize, - tyConSelIds, + tyConDataCons, tyConDataCons_maybe, tyConSingleDataCon_maybe, + tyConFamilySize, tyConStupidTheta, tyConArity, - isClassTyCon, tyConClass_maybe, - synTyConDefn, synTyConRhs, + tyConClass_maybe, + tyConFamInst_maybe, tyConFamilyCoercion_maybe, + synTyConDefn, synTyConRhs, synTyConType, synTyConResKind, tyConExtName, -- External name for foreign types + algTyConRhs, + newTyConRhs, newTyConEtadRhs, unwrapNewTyCon_maybe, + assocTyConArgPoss_maybe, + tupleTyConBoxity, - maybeTyConSingleCon, + -- ** Manipulating TyCons + tcExpandTyCon_maybe, coreExpandTyCon_maybe, + makeTyConAbstract, + newTyConCo_maybe, + setTyConArgPoss, - -- Generics - tyConHasGenerics + -- * Primitive representations of Types + PrimRep(..), + tyConPrimRep, + primRepSizeW ) where #include "HsVersions.h" -import {-# SOURCE #-} TypeRep ( Type, PredType ) - -- Should just be Type(Type), but this fails due to bug present up to - -- and including 4.02 involving slurping of hi-boot files. Bug is now fixed. - +import {-# SOURCE #-} TypeRep ( Kind, Type, PredType ) import {-# SOURCE #-} DataCon ( DataCon, isVanillaDataCon ) - -import Var ( TyVar, Id ) -import Class ( Class ) -import Kind ( Kind ) -import BasicTypes ( Arity, RecFlag(..), Boxity(..), isBoxed ) -import Name ( Name, nameUnique, NamedThing(getName) ) -import PrelNames ( Unique, Uniquable(..) ) -import Maybes ( orElse ) +import Var +import Class +import BasicTypes +import Name +import PrelNames +import Maybes import Outputable import FastString +import Constants +import Data.List( elemIndex ) \end{code} %************************************************************************ @@ -79,138 +102,319 @@ import FastString %************************************************************************ \begin{code} +-- | Represents type constructors. Type constructors are introduced by things such as: +-- +-- 1) Data declarations: @data Foo = ...@ creates the @Foo@ type constructor of kind @*@ +-- +-- 2) Type synonyms: @type Foo = ...@ creates the @Foo@ type constructor +-- +-- 3) Newtypes: @newtype Foo a = MkFoo ...@ creates the @Foo@ type constructor of kind @* -> *@ +-- +-- 4) Class declarations: @class Foo where@ creates the @Foo@ type constructor of kind @*@ +-- +-- 5) Type coercions! This is because we represent a coercion from @t1@ to @t2@ as a 'Type', where +-- that type has kind @t1 ~ t2@. See "Coercion" for more on this +-- +-- This data type also encodes a number of primitive, built in type constructors such as those +-- for function and tuple types. data TyCon - = FunTyCon { + = -- | The function type constructor, @(->)@ + FunTyCon { tyConUnique :: Unique, tyConName :: Name, tyConKind :: Kind, tyConArity :: Arity } - - | AlgTyCon { -- Data type, and newtype decls. - -- All lifted, all boxed + -- | Algebraic type constructors, which are defined to be those arising @data@ type and @newtype@ declarations. + -- All these constructors are lifted and boxed. See 'AlgTyConRhs' for more information. + | AlgTyCon { tyConUnique :: Unique, tyConName :: Name, tyConKind :: Kind, tyConArity :: Arity, - - tyConTyVars :: [TyVar], -- Scopes over (a) the [PredType] in AlgTyConRhs.DataTyCon - -- (b) the cached types in AlgTyConRhs.NewTyCon - -- But not over the data constructors - argVrcs :: ArgVrcs, - algTcSelIds :: [Id], -- Its record selectors (empty if none): + tyConTyVars :: [TyVar], -- ^ The type variables used in the type constructor. + -- Precisely, this list scopes over: + -- + -- 1. The 'algTcStupidTheta' + -- + -- 2. The cached types in 'algTyConRhs.NewTyCon' + -- + -- 3. The family instance types if present + -- + -- Note that it does /not/ scope over the data constructors. + + algTcGadtSyntax :: Bool, -- ^ Was the data type declared with GADT syntax? If so, + -- that doesn't mean it's a true GADT; only that the "where" + -- form was used. This field is used only to guide + -- pretty-printing + algTcStupidTheta :: [PredType], -- ^ The \"stupid theta\" for the data type (always empty for GADTs). + -- A \"stupid theta\" is the context to the left of an algebraic type + -- declaration, e.g. @Eq a@ in the declaration @data Eq a => T a ...@. + + algTcRhs :: AlgTyConRhs, -- ^ Contains information about the data constructors of the algebraic type + + algTcRec :: RecFlag, -- ^ Tells us whether the data type is part of a mutually-recursive group or not + + hasGenerics :: Bool, -- ^ Whether generic (in the -XGenerics sense) to\/from functions are + -- available in the exports of the data type's source module. + + algTcParent :: TyConParent -- ^ Gives the class or family declaration 'TyCon' for derived 'TyCon's + -- representing class or family instances, respectively. See also 'synTcParent' + } - algTcStupidTheta :: [PredType], -- The "stupid theta" for the data type - -- (always empty for GADTs) + -- | Represents the infinite family of tuple type constructors, @()@, @(a,b)@, @(# a, b #)@ etc. + | TupleTyCon { + tyConUnique :: Unique, + tyConName :: Name, + tyConKind :: Kind, + tyConArity :: Arity, + tyConBoxed :: Boxity, + tyConTyVars :: [TyVar], + dataCon :: DataCon, -- ^ Corresponding tuple data constructor + hasGenerics :: Bool + } + + -- | Represents type synonyms + | SynTyCon { + tyConUnique :: Unique, + tyConName :: Name, + tyConKind :: Kind, + tyConArity :: Arity, - algTcRhs :: AlgTyConRhs, -- Data constructors in here + tyConTyVars :: [TyVar], -- Bound tyvars - algTcRec :: RecFlag, -- Tells whether the data type is part of - -- a mutually-recursive group or not + synTcRhs :: SynTyConRhs, -- ^ Contains information about the expansion of the synonym - hasGenerics :: Bool, -- True <=> generic to/from functions are available - -- (in the exports of the data type's source module) + synTcParent :: TyConParent -- ^ Gives the family declaration 'TyCon' of 'TyCon's representing family instances - algTcClass :: Maybe Class - -- Just cl if this tycon came from a class declaration } - | PrimTyCon { -- Primitive types; cannot be defined in Haskell - -- Now includes foreign-imported types + -- | Primitive types; cannot be defined in Haskell. This includes the usual suspects (such as @Int#@) + -- as well as foreign-imported types and kinds + | PrimTyCon { tyConUnique :: Unique, tyConName :: Name, tyConKind :: Kind, - tyConArity :: Arity, - argVrcs :: ArgVrcs, + tyConArity :: Arity, -- SLPJ Oct06: I'm not sure what the significance + -- of the arity of a primtycon is! primTyConRep :: PrimRep, - -- Many primitive tycons are unboxed, but some are - -- boxed (represented by pointers). The CgRep tells. + -- ^ Many primitive tycons are unboxed, but some are + -- boxed (represented by pointers). This 'PrimRep' holds + -- that information - isUnLifted :: Bool, -- Most primitive tycons are unlifted, - -- but foreign-imported ones may not be - tyConExtName :: Maybe FastString -- Just xx for foreign-imported types + isUnLifted :: Bool, -- ^ Most primitive tycons are unlifted (may not contain bottom) + -- but foreign-imported ones may be lifted + tyConExtName :: Maybe FastString -- ^ @Just e@ for foreign-imported types, holds the name of the imported thing } - | TupleTyCon { + -- | Type coercions, such as @(~)@, @sym@, @trans@, @left@ and @right@. + -- INVARIANT: coercions are always fully applied + | CoercionTyCon { tyConUnique :: Unique, - tyConName :: Name, - tyConKind :: Kind, + tyConName :: Name, tyConArity :: Arity, - tyConBoxed :: Boxity, - tyConTyVars :: [TyVar], - dataCon :: DataCon, - hasGenerics :: Bool + coKindFun :: [Type] -> (Type,Type) + -- ^ Function that when given a list of the type arguments to the 'TyCon' + -- constructs the types that the resulting coercion relates. + -- + -- INVARIANT: 'coKindFun' is always applied to exactly 'tyConArity' args + -- E.g. for @trans (c1 :: ta=tb) (c2 :: tb=tc)@, the 'coKindFun' returns + -- the kind as a pair of types: @(ta, tc)@ } - | SynTyCon { - tyConUnique :: Unique, - tyConName :: Name, - tyConKind :: Kind, - tyConArity :: Arity, - - tyConTyVars :: [TyVar], -- Bound tyvars - synTcRhs :: Type, -- Right-hand side, mentioning these type vars. - -- Acts as a template for the expansion when - -- the tycon is applied to some types. - argVrcs :: ArgVrcs + -- | Super-kinds. These are "kinds-of-kinds" and are never seen in Haskell source programs. + -- There are only two super-kinds: TY (aka "box"), which is the super-kind of kinds that + -- construct types eventually, and CO (aka "diamond"), which is the super-kind of kinds + -- that just represent coercions. + -- + -- Super-kinds have no kind themselves, and have arity zero + | SuperKindTyCon { + tyConUnique :: Unique, + tyConName :: Name } +-- | Names of the fields in an algebraic record type type FieldLabel = Name -type ArgVrcs = [(Bool,Bool)] -- Tyvar variance info: [(occPos,occNeg)] - -- [] means "no information, assume the worst" - +-- | Represents right-hand-sides of 'TyCon's for algebraic types data AlgTyConRhs - = AbstractTyCon -- We know nothing about this data type, except - -- that it's represented by a pointer - -- Used when we export a data type abstractly into - -- an hi file + -- | Says that we know nothing about this data type, except that it's represented + -- by a pointer. Used when we export a data type abstractly into an .hi file. + = AbstractTyCon + + -- | Represents an open type family without a fixed right hand + -- side. Additional instances can appear at any time. + -- + -- These are introduced by either a top level declaration: + -- + -- > data T a :: * + -- + -- Or an assoicated data type declaration, within a class declaration: + -- + -- > class C a b where + -- > data T b :: * + + | OpenTyCon { + otArgPoss :: AssocFamilyPermutation + } + + -- | Information about those 'TyCon's derived from a @data@ declaration. This includes + -- data types with no constructors at all. | DataTyCon { data_cons :: [DataCon], - -- The constructors; can be empty if the user declares + -- ^ The data type constructors; can be empty if the user declares -- the type to have no constructors - -- INVARIANT: Kept in order of increasing tag - -- (see the tag assignment in DataCon.mkDataCon) - is_enum :: Bool -- Cached: True <=> an enumeration type - } -- Includes data types with no constructors. + -- + -- INVARIANT: Kept in order of increasing 'DataCon' tag + + -- (see the tag assignment in DataCon.mkDataCon) + is_enum :: Bool -- ^ Cached value: is this an enumeration type? (See 'isEnumerationTyCon') + } + -- | Information about those 'TyCon's derived from a @newtype@ declaration | NewTyCon { - data_con :: DataCon, -- The unique constructor; it has no existentials - - nt_rhs :: Type, -- Cached: the argument type of the constructor - -- = the representation type of the tycon - - nt_etad_rhs :: ([TyVar], Type) , - -- The same again, but this time eta-reduced - -- hence the [TyVar] which may be shorter than the declared - -- arity of the TyCon. See Note [Newtype eta] - - nt_rep :: Type -- Cached: the *ultimate* representation type - -- By 'ultimate' I mean that the top-level constructor - -- of the rep type is not itself a newtype or type synonym. - -- The rep type isn't entirely simple: - -- for a recursive newtype we pick () as the rep type - -- newtype T = MkT T - -- - -- This one does not need to be eta reduced; hence its - -- free type variables are conveniently tyConTyVars - -- Thus: - -- newtype T a = MkT [(a,Int)] - -- The rep type is [(a,Int)] - -- NB: the rep type isn't necessarily the original RHS of the - -- newtype decl, because the rep type looks through other - } -- newtypes. + data_con :: DataCon, -- ^ The unique constructor for the @newtype@. It has no existentials + + nt_rhs :: Type, -- ^ Cached value: the argument type of the constructor, which + -- is just the representation type of the 'TyCon' (remember that + -- @newtype@s do not exist at runtime so need a different representation + -- type). + -- + -- The free 'TyVar's of this type are the 'tyConTyVars' from the corresponding + -- 'TyCon' + + nt_etad_rhs :: ([TyVar], Type), + -- ^ Same as the 'nt_rhs', but this time eta-reduced. Hence the list of 'TyVar's in + -- this field may be shorter than the declared arity of the 'TyCon'. + + -- See Note [Newtype eta] + + nt_co :: Maybe TyCon -- ^ A 'TyCon' (which is always a 'CoercionTyCon') that can have a 'Coercion' + -- extracted from it to create the @newtype@ from the representation 'Type'. + -- + -- This field is optional for non-recursive @newtype@s only. + + -- See Note [Newtype coercions] + -- Invariant: arity = #tvs in nt_etad_rhs; + -- See Note [Newtype eta] + -- Watch out! If any newtypes become transparent + -- again check Trac #1072. + } +type AssocFamilyPermutation + = Maybe [Int] -- Nothing for *top-level* type families + -- For *associated* type families, gives the position + -- of that 'TyVar' in the class argument list (0-indexed) + -- e.g. class C a b c where { type F c a :: *->* } + -- Then we get Just [2,0] + -- For *synonyms*, the length of the list is identical to + -- the TyCon's arity + -- For *data types*, the length may be smaller than the + -- TyCon's arity; e.g. class C a where { data D a :: *->* } + -- here D gets arity 2 + +-- | Extract those 'DataCon's that we are able to learn about. Note that visibility in this sense does not +-- correspond to visibility in the context of any particular user program! visibleDataCons :: AlgTyConRhs -> [DataCon] visibleDataCons AbstractTyCon = [] +visibleDataCons OpenTyCon {} = [] visibleDataCons (DataTyCon{ data_cons = cs }) = cs visibleDataCons (NewTyCon{ data_con = c }) = [c] + +-- ^ Both type classes as well as family instances imply implicit +-- type constructors. These implicit type constructors refer to their parent +-- structure (ie, the class or family from which they derive) using a type of +-- the following form. We use 'TyConParent' for both algebraic and synonym +-- types, but the variant 'ClassTyCon' will only be used by algebraic 'TyCon's. +data TyConParent + = -- | An ordinary type constructor has no parent. + NoParentTyCon + + -- | Type constructors representing a class dictionary. + | ClassTyCon + Class -- INVARIANT: the classTyCon of this Class is the current tycon + + -- | Type constructors representing an instance of a type family. Parameters: + -- + -- 1) The type family in question + -- + -- 2) Instance types; free variables are the 'tyConTyVars' + -- of the current 'TyCon' (not the family one). INVARIANT: + -- the number of types matches the arity of the family 'TyCon' + -- + -- 3) A 'CoercionTyCon' identifying the representation + -- type with the type instance family + | FamilyTyCon + TyCon + [Type] + TyCon -- c.f. Note [Newtype coercions] + + -- + -- E.g. data intance T [a] = ... + -- gives a representation tycon: + -- data :R7T a = ... + -- axiom co a :: T [a] ~ :R7T a + -- with :R7T's algTcParent = FamilyTyCon T [a] co + +-- | Checks the invariants of a 'TyConParent' given the appropriate type class name, if any +okParent :: Name -> TyConParent -> Bool +okParent _ NoParentTyCon = True +okParent tc_name (ClassTyCon cls) = tyConName (classTyCon cls) == tc_name +okParent _ (FamilyTyCon fam_tc tys _co_tc) = tyConArity fam_tc == length tys + +-------------------- + +-- | Information pertaining to the expansion of a type synonym (@type@) +data SynTyConRhs + = OpenSynTyCon -- e.g. type family F x y :: * -> * + Kind -- Kind of the "rhs"; ie *excluding type indices* + -- In the example, the kind is (*->*) + AssocFamilyPermutation + + | SynonymTyCon Type -- ^ The synonym mentions head type variables. It acts as a + -- template for the expansion when the 'TyCon' is applied to some + -- types. \end{code} +Note [Newtype coercions] +~~~~~~~~~~~~~~~~~~~~~~~~ +The NewTyCon field nt_co is a a TyCon (a coercion constructor in fact) +which is used for coercing from the representation type of the +newtype, to the newtype itself. For example, + + newtype T a = MkT (a -> a) + +the NewTyCon for T will contain nt_co = CoT where CoT t : T t ~ t -> +t. This TyCon is a CoercionTyCon, so it does not have a kind on its +own; it basically has its own typing rule for the fully-applied +version. If the newtype T has k type variables then CoT has arity at +most k. In the case that the right hand side is a type application +ending with the same type variables as the left hand side, we +"eta-contract" the coercion. So if we had + + newtype S a = MkT [a] + +then we would generate the arity 0 coercion CoS : S ~ []. The +primary reason we do this is to make newtype deriving cleaner. + +In the paper we'd write + axiom CoT : (forall t. T t) ~ (forall t. [t]) +and then when we used CoT at a particular type, s, we'd say + CoT @ s +which encodes as (TyConApp instCoercionTyCon [TyConApp CoT [], s]) + +But in GHC we instead make CoT into a new piece of type syntax, CoercionTyCon, +(like instCoercionTyCon, symCoercionTyCon etc), which must always +be saturated, but which encodes as + TyConApp CoT [s] +In the vocabulary of the paper it's as if we had axiom declarations +like + axiom CoT t : T t ~ [t] + Note [Newtype eta] ~~~~~~~~~~~~~~~~~~ Consider @@ -235,12 +439,53 @@ Source code: w2 :: Foo T w2 = MkFoo (\(MkT x) -> case w1 of MkFoo f -> f x) -After desugaring, and discading the data constructors for the newtypes, +After desugaring, and discarding the data constructors for the newtypes, we get: w2 :: Foo T w2 = w1 And now Lint complains unless Foo T == Foo [], and that requires T==[] +This point carries over to the newtype coercion, because we need to +say + w2 = w1 `cast` Foo CoT + +so the coercion tycon CoT must have + kind: T ~ [] + and arity: 0 + + +Note [Indexed data types] (aka data type families) +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + See also Note [Wrappers for data instance tycons] in MkId.lhs + +Consider + data family T a + + data instance T (b,c) where + T1 :: b -> c -> T (b,c) + +Then + * T is the "family TyCon" + + * We make "representation TyCon" :R1T, thus: + data :R1T b c where + T1 :: forall b c. b -> c -> :R1T b c + + * It has a top-level coercion connecting it to the family TyCon + + axiom :Co:R1T b c : T (b,c) ~ :R1T b c + + * The data contructor T1 has a wrapper (which is what the source-level + "T1" invokes): + + $WT1 :: forall b c. b -> c -> T (b,c) + $WT1 b c (x::b) (y::c) = T1 b c x y `cast` sym (:Co:R1T b c) + + * The representation TyCon :R1T has an AlgTyConParent of + + FamilyTyCon T [(b,c)] :Co:R1T + + %************************************************************************ %* * @@ -248,10 +493,6 @@ And now Lint complains unless Foo T == Foo [], and that requires T==[] %* * %************************************************************************ -A PrimRep is an abstraction of a type. It contains information that -the code generator needs in order to pass arguments, return results, -and store values of this type. - A PrimRep is somewhat similar to a CgRep (see codeGen/SMRep) and a MachRep (see cmm/MachOp), although each of these types has a distinct and clearly defined purpose: @@ -267,16 +508,35 @@ and clearly defined purpose: reps that don't have corresponding Haskell types). \begin{code} +-- | A 'PrimRep' is an abstraction of a type. It contains information that +-- the code generator needs in order to pass arguments, return results, +-- and store values of this type. data PrimRep = VoidRep | PtrRep - | IntRep -- signed, word-sized - | WordRep -- unsinged, word-sized - | Int64Rep -- signed, 64 bit (32-bit words only) - | Word64Rep -- unsigned, 64 bit (32-bit words only) - | AddrRep -- a pointer, but not to a Haskell value + | IntRep -- ^ Signed, word-sized value + | WordRep -- ^ Unsigned, word-sized value + | Int64Rep -- ^ Signed, 64 bit value (with 32-bit words only) + | Word64Rep -- ^ Unsigned, 64 bit value (with 32-bit words only) + | AddrRep -- ^ A pointer, but /not/ to a Haskell value (use 'PtrRep') | FloatRep | DoubleRep + deriving( Eq, Show ) + +instance Outputable PrimRep where + ppr r = text (show r) + +-- | Find the size of a 'PrimRep', in words +primRepSizeW :: PrimRep -> Int +primRepSizeW IntRep = 1 +primRepSizeW WordRep = 1 +primRepSizeW Int64Rep = wORD64_SIZE `quot` wORD_SIZE +primRepSizeW Word64Rep= wORD64_SIZE `quot` wORD_SIZE +primRepSizeW FloatRep = 1 -- NB. might not take a full word +primRepSizeW DoubleRep= dOUBLE_SIZE `quot` wORD_SIZE +primRepSizeW AddrRep = 1 +primRepSizeW PtrRep = 1 +primRepSizeW VoidRep = 0 \end{code} %************************************************************************ @@ -292,6 +552,9 @@ module mutual-recursion. And they aren't called from many places. So we compromise, and move their Kind calculation to the call site. \begin{code} +-- | Given the name of the function type constructor and it's kind, create the +-- corresponding 'TyCon'. It is reccomended to use 'TypeRep.funTyCon' if you want +-- this functionality mkFunTyCon :: Name -> Kind -> TyCon mkFunTyCon name kind = FunTyCon { @@ -301,42 +564,46 @@ mkFunTyCon name kind tyConArity = 2 } --- This is the making of a TyCon. Just the same as the old mkAlgTyCon, --- but now you also have to pass in the generic information about the type --- constructor - you can get hold of it easily (see Generics module) -mkAlgTyCon name kind tyvars argvrcs stupid rhs sel_ids is_rec gen_info +-- | This is the making of an algebraic 'TyCon'. Notably, you have to pass in the generic (in the -XGenerics sense) +-- information about the type constructor - you can get hold of it easily (see Generics module) +mkAlgTyCon :: Name + -> Kind -- ^ Kind of the resulting 'TyCon' + -> [TyVar] -- ^ 'TyVar's scoped over: see 'tyConTyVars'. Arity is inferred from the length of this list + -> [PredType] -- ^ Stupid theta: see 'algTcStupidTheta' + -> AlgTyConRhs -- ^ Information about dat aconstructors + -> TyConParent + -> RecFlag -- ^ Is the 'TyCon' recursive? + -> Bool -- ^ Does it have generic functions? See 'hasGenerics' + -> Bool -- ^ Was the 'TyCon' declared with GADT syntax? + -> TyCon +mkAlgTyCon name kind tyvars stupid rhs parent is_rec gen_info gadt_syn = AlgTyCon { tyConName = name, tyConUnique = nameUnique name, tyConKind = kind, tyConArity = length tyvars, tyConTyVars = tyvars, - argVrcs = argvrcs, algTcStupidTheta = stupid, algTcRhs = rhs, - algTcSelIds = sel_ids, - algTcClass = Nothing, + algTcParent = ASSERT( okParent name parent ) parent, algTcRec = is_rec, + algTcGadtSyntax = gadt_syn, hasGenerics = gen_info } -mkClassTyCon name kind tyvars argvrcs rhs clas is_rec - = AlgTyCon { - tyConName = name, - tyConUnique = nameUnique name, - tyConKind = kind, - tyConArity = length tyvars, - tyConTyVars = tyvars, - argVrcs = argvrcs, - algTcStupidTheta = [], - algTcRhs = rhs, - algTcSelIds = [], - algTcClass = Just clas, - algTcRec = is_rec, - hasGenerics = False - } - - +-- | Simpler specialization of 'mkAlgTyCon' for classes +mkClassTyCon :: Name -> Kind -> [TyVar] -> AlgTyConRhs -> Class -> RecFlag -> TyCon +mkClassTyCon name kind tyvars rhs clas is_rec = + mkAlgTyCon name kind tyvars [] rhs (ClassTyCon clas) is_rec False False + +mkTupleTyCon :: Name + -> Kind -- ^ Kind of the resulting 'TyCon' + -> Arity -- ^ Arity of the tuple + -> [TyVar] -- ^ 'TyVar's scoped over: see 'tyConTyVars' + -> DataCon + -> Boxity -- ^ Whether the tuple is boxed or unboxed + -> Bool -- ^ Does it have generic functions? See 'hasGenerics' + -> TyCon mkTupleTyCon name kind arity tyvars con boxed gen_info = TupleTyCon { tyConUnique = nameUnique name, @@ -349,44 +616,57 @@ mkTupleTyCon name kind arity tyvars con boxed gen_info hasGenerics = gen_info } --- Foreign-imported (.NET) type constructors are represented --- as primitive, but *lifted*, TyCons for now. They are lifted --- because the Haskell type T representing the (foreign) .NET --- type T is actually implemented (in ILX) as a thunk -mkForeignTyCon name ext_name kind arity arg_vrcs +-- ^ Foreign-imported (.NET) type constructors are represented +-- as primitive, but /lifted/, 'TyCons' for now. They are lifted +-- because the Haskell type @T@ representing the (foreign) .NET +-- type @T@ is actually implemented (in ILX) as a @thunk@ +mkForeignTyCon :: Name + -> Maybe FastString -- ^ Name of the foreign imported thing, maybe + -> Kind + -> Arity + -> TyCon +mkForeignTyCon name ext_name kind arity = PrimTyCon { tyConName = name, tyConUnique = nameUnique name, tyConKind = kind, tyConArity = arity, - argVrcs = arg_vrcs, primTyConRep = PtrRep, -- they all do isUnLifted = False, tyConExtName = ext_name } --- most Prim tycons are lifted -mkPrimTyCon name kind arity arg_vrcs rep - = mkPrimTyCon' name kind arity arg_vrcs rep True +-- | Create an unlifted primitive 'TyCon', such as @Int#@ +mkPrimTyCon :: Name -> Kind -> Arity -> PrimRep -> TyCon +mkPrimTyCon name kind arity rep + = mkPrimTyCon' name kind arity rep True --- but RealWorld is lifted -mkLiftedPrimTyCon name kind arity arg_vrcs rep - = mkPrimTyCon' name kind arity arg_vrcs rep False +-- | Create the special void 'TyCon' which is unlifted and has 'VoidRep' +mkVoidPrimTyCon :: Name -> Kind -> Arity -> TyCon +mkVoidPrimTyCon name kind arity + = mkPrimTyCon' name kind arity VoidRep True -mkPrimTyCon' name kind arity arg_vrcs rep is_unlifted +-- | Create a lifted primitive 'TyCon' such as @RealWorld@ +mkLiftedPrimTyCon :: Name -> Kind -> Arity -> PrimRep -> TyCon +mkLiftedPrimTyCon name kind arity rep + = mkPrimTyCon' name kind arity rep False + +mkPrimTyCon' :: Name -> Kind -> Arity -> PrimRep -> Bool -> TyCon +mkPrimTyCon' name kind arity rep is_unlifted = PrimTyCon { tyConName = name, tyConUnique = nameUnique name, tyConKind = kind, tyConArity = arity, - argVrcs = arg_vrcs, primTyConRep = rep, isUnLifted = is_unlifted, tyConExtName = Nothing } -mkSynTyCon name kind tyvars rhs argvrcs +-- | Create a type synonym 'TyCon' +mkSynTyCon :: Name -> Kind -> [TyVar] -> SynTyConRhs -> TyConParent -> TyCon +mkSynTyCon name kind tyvars rhs parent = SynTyCon { tyConName = name, tyConUnique = nameUnique name, @@ -394,8 +674,26 @@ mkSynTyCon name kind tyvars rhs argvrcs tyConArity = length tyvars, tyConTyVars = tyvars, synTcRhs = rhs, - argVrcs = argvrcs + synTcParent = parent + } + +-- | Create a coercion 'TyCon' +mkCoercionTyCon :: Name -> Arity -> ([Type] -> (Type,Type)) -> TyCon +mkCoercionTyCon name arity kindRule + = CoercionTyCon { + tyConName = name, + tyConUnique = nameUnique name, + tyConArity = arity, + coKindFun = kindRule } + +-- | Create a super-kind 'TyCon' +mkSuperKindTyCon :: Name -> TyCon -- Super kinds always have arity zero +mkSuperKindTyCon name + = SuperKindTyCon { + tyConName = name, + tyConUnique = nameUnique name + } \end{code} \begin{code} @@ -403,109 +701,232 @@ isFunTyCon :: TyCon -> Bool isFunTyCon (FunTyCon {}) = True isFunTyCon _ = False +-- | Test if the 'TyCon' is algebraic but abstract (invisible data constructors) isAbstractTyCon :: TyCon -> Bool isAbstractTyCon (AlgTyCon { algTcRhs = AbstractTyCon }) = True isAbstractTyCon _ = False +-- | Make an algebraic 'TyCon' abstract. Panics if the supplied 'TyCon' is not algebraic makeTyConAbstract :: TyCon -> TyCon makeTyConAbstract tc@(AlgTyCon {}) = tc { algTcRhs = AbstractTyCon } makeTyConAbstract tc = pprPanic "makeTyConAbstract" (ppr tc) +-- | Does this 'TyCon' represent something that cannot be defined in Haskell? isPrimTyCon :: TyCon -> Bool isPrimTyCon (PrimTyCon {}) = True isPrimTyCon _ = False +-- | Is this 'TyCon' unlifted (i.e. cannot contain bottom)? Note that this can only +-- be true for primitive and unboxed-tuple 'TyCon's isUnLiftedTyCon :: TyCon -> Bool isUnLiftedTyCon (PrimTyCon {isUnLifted = is_unlifted}) = is_unlifted isUnLiftedTyCon (TupleTyCon {tyConBoxed = boxity}) = not (isBoxed boxity) isUnLiftedTyCon _ = False --- isAlgTyCon returns True for both @data@ and @newtype@ +-- | Returns @True@ if the supplied 'TyCon' resulted from either a @data@ or @newtype@ declaration isAlgTyCon :: TyCon -> Bool isAlgTyCon (AlgTyCon {}) = True isAlgTyCon (TupleTyCon {}) = True -isAlgTyCon other = False +isAlgTyCon _ = False isDataTyCon :: TyCon -> Bool --- isDataTyCon returns True for data types that are represented by --- heap-allocated constructors. --- These are srcutinised by Core-level @case@ expressions, and they --- get info tables allocated for them. --- True for all @data@ types --- False for newtypes --- unboxed tuples -isDataTyCon tc@(AlgTyCon {algTcRhs = rhs}) +-- ^ Returns @True@ for data types that are /definitely/ represented by +-- heap-allocated constructors. These are scrutinised by Core-level +-- @case@ expressions, and they get info tables allocated for them. +-- +-- Generally, the function will be true for all @data@ types and false +-- for @newtype@s, unboxed tuples and type family 'TyCon's. But it is +-- not guarenteed to return @True@ in all cases that it could. +-- +-- NB: for a data type family, only the /instance/ 'TyCon's +-- get an info table. The family declaration 'TyCon' does not +isDataTyCon (AlgTyCon {algTcRhs = rhs}) = case rhs of + OpenTyCon {} -> False DataTyCon {} -> True NewTyCon {} -> False - AbstractTyCon -> pprPanic "isDataTyCon" (ppr tc) - + AbstractTyCon -> False -- We don't know, so return False isDataTyCon (TupleTyCon {tyConBoxed = boxity}) = isBoxed boxity -isDataTyCon other = False +isDataTyCon _ = False +-- | Is this 'TyCon' that for a @newtype@ isNewTyCon :: TyCon -> Bool -isNewTyCon (AlgTyCon {algTcRhs = NewTyCon {}}) = True -isNewTyCon other = False +isNewTyCon (AlgTyCon {algTcRhs = NewTyCon {}}) = True +isNewTyCon _ = False + +-- | Take a 'TyCon' apart into the 'TyVar's it scopes over, the 'Type' it expands +-- into, and (possibly) a coercion from the representation type to the @newtype@. +-- Returns @Nothing@ if this is not possible. +unwrapNewTyCon_maybe :: TyCon -> Maybe ([TyVar], Type, Maybe TyCon) +unwrapNewTyCon_maybe (AlgTyCon { tyConTyVars = tvs, + algTcRhs = NewTyCon { nt_co = mb_co, + nt_rhs = rhs }}) + = Just (tvs, rhs, mb_co) +unwrapNewTyCon_maybe _ = Nothing isProductTyCon :: TyCon -> Bool --- A "product" tycon --- has *one* constructor, --- is *not* existential --- but --- may be DataType or NewType, --- may be unboxed or not, --- may be recursive or not +-- | A /product/ 'TyCon' must both: +-- +-- 1. Have /one/ constructor +-- +-- 2. /Not/ be existential +-- +-- However other than this there are few restrictions: they may be @data@ or @newtype@ +-- 'TyCon's of any boxity and may even be recursive. isProductTyCon tc@(AlgTyCon {}) = case algTcRhs tc of DataTyCon{ data_cons = [data_con] } -> isVanillaDataCon data_con NewTyCon {} -> True - other -> False + _ -> False isProductTyCon (TupleTyCon {}) = True -isProductTyCon other = False +isProductTyCon _ = False +-- | Is this a 'TyCon' representing a type synonym (@type@)? isSynTyCon :: TyCon -> Bool isSynTyCon (SynTyCon {}) = True isSynTyCon _ = False +-- As for newtypes, it is in some contexts important to distinguish between +-- closed synonyms and synonym families, as synonym families have no unique +-- right hand side to which a synonym family application can expand. +-- + +-- | Is this a synonym 'TyCon' that can have no further instances appear? +isClosedSynTyCon :: TyCon -> Bool +isClosedSynTyCon tycon = isSynTyCon tycon && not (isOpenTyCon tycon) + +-- | Is this a synonym 'TyCon' that can have may have further instances appear? +isOpenSynTyCon :: TyCon -> Bool +isOpenSynTyCon tycon = isSynTyCon tycon && isOpenTyCon tycon + +-- | Is this an algebraic 'TyCon' declared with the GADT syntax? +isGadtSyntaxTyCon :: TyCon -> Bool +isGadtSyntaxTyCon (AlgTyCon { algTcGadtSyntax = res }) = res +isGadtSyntaxTyCon _ = False + +-- | Is this an algebraic 'TyCon' which is just an enumeration of values? isEnumerationTyCon :: TyCon -> Bool isEnumerationTyCon (AlgTyCon {algTcRhs = DataTyCon { is_enum = res }}) = res -isEnumerationTyCon other = False +isEnumerationTyCon _ = False + +-- | Is this a 'TyCon', synonym or otherwise, that may have further instances appear? +isOpenTyCon :: TyCon -> Bool +isOpenTyCon (SynTyCon {synTcRhs = OpenSynTyCon {}}) = True +isOpenTyCon (AlgTyCon {algTcRhs = OpenTyCon {}}) = True +isOpenTyCon _ = False + +-- | Extract the mapping from 'TyVar' indexes to indexes in the corresponding family +-- argument lists form an open 'TyCon' of any sort, if the given 'TyCon' is indeed +-- such a beast and that information is available +assocTyConArgPoss_maybe :: TyCon -> Maybe [Int] +assocTyConArgPoss_maybe (AlgTyCon { + algTcRhs = OpenTyCon {otArgPoss = poss}}) = poss +assocTyConArgPoss_maybe (SynTyCon { synTcRhs = OpenSynTyCon _ poss }) = poss +assocTyConArgPoss_maybe _ = Nothing + +-- | Are we able to extract informationa 'TyVar' to class argument list +-- mappping from a given 'TyCon'? +isTyConAssoc :: TyCon -> Bool +isTyConAssoc = isJust . assocTyConArgPoss_maybe + +-- | Set the AssocFamilyPermutation structure in an +-- associated data or type synonym. The [TyVar] are the +-- class type variables. Remember, the tyvars of an associated +-- data/type are a subset of the class tyvars; except that an +-- associated data type can have extra type variables at the +-- end (see Note [Avoid name clashes for associated data types] in TcHsType) +setTyConArgPoss :: [TyVar] -> TyCon -> TyCon +setTyConArgPoss clas_tvs tc + = case tc of + AlgTyCon { algTcRhs = rhs } -> tc { algTcRhs = rhs {otArgPoss = Just ps} } + SynTyCon { synTcRhs = OpenSynTyCon ki _ } -> tc { synTcRhs = OpenSynTyCon ki (Just ps) } + _ -> pprPanic "setTyConArgPoss" (ppr tc) + where + ps = catMaybes [tv `elemIndex` clas_tvs | tv <- tyConTyVars tc] + -- We will get Nothings for the "extra" type variables in an + -- associated data type -isTupleTyCon :: TyCon -> Bool -- The unit tycon didn't used to be classed as a tuple tycon -- but I thought that was silly so I've undone it -- If it can't be for some reason, it should be a AlgTyCon +isTupleTyCon :: TyCon -> Bool +-- ^ Does this 'TyCon' represent a tuple? -- --- NB: when compiling Data.Tuple, the tycons won't reply True to --- isTupleTyCon, becuase they are built as AlgTyCons. However they +-- NB: when compiling @Data.Tuple@, the tycons won't reply @True@ to +-- 'isTupleTyCon', becuase they are built as 'AlgTyCons'. However they -- get spat into the interface file as tuple tycons, so I don't think -- it matters. isTupleTyCon (TupleTyCon {}) = True -isTupleTyCon other = False +isTupleTyCon _ = False +-- | Is this the 'TyCon' for an unboxed tuple? isUnboxedTupleTyCon :: TyCon -> Bool isUnboxedTupleTyCon (TupleTyCon {tyConBoxed = boxity}) = not (isBoxed boxity) -isUnboxedTupleTyCon other = False +isUnboxedTupleTyCon _ = False +-- | Is this the 'TyCon' for a boxed tuple? isBoxedTupleTyCon :: TyCon -> Bool isBoxedTupleTyCon (TupleTyCon {tyConBoxed = boxity}) = isBoxed boxity -isBoxedTupleTyCon other = False +isBoxedTupleTyCon _ = False +-- | Extract the boxity of the given 'TyCon', if it is a 'TupleTyCon'. +-- Panics otherwise +tupleTyConBoxity :: TyCon -> Boxity tupleTyConBoxity tc = tyConBoxed tc +-- | Is this a recursive 'TyCon'? isRecursiveTyCon :: TyCon -> Bool isRecursiveTyCon (AlgTyCon {algTcRec = Recursive}) = True -isRecursiveTyCon other = False +isRecursiveTyCon _ = False +-- | Did this 'TyCon' originate from type-checking a .h*-boot file? isHiBootTyCon :: TyCon -> Bool -- Used for knot-tying in hi-boot files isHiBootTyCon (AlgTyCon {algTcRhs = AbstractTyCon}) = True -isHiBootTyCon other = False +isHiBootTyCon _ = False +-- | Is this the 'TyCon' of a foreign-imported type constructor? isForeignTyCon :: TyCon -> Bool --- isForeignTyCon identifies foreign-imported type constructors isForeignTyCon (PrimTyCon {tyConExtName = Just _}) = True -isForeignTyCon other = False +isForeignTyCon _ = False + +-- | Is this a super-kind 'TyCon'? +isSuperKindTyCon :: TyCon -> Bool +isSuperKindTyCon (SuperKindTyCon {}) = True +isSuperKindTyCon _ = False + +-- | Attempt to pull a 'TyCon' apart into the arity and 'coKindFun' of +-- a coercion 'TyCon'. Returns @Nothing@ if the 'TyCon' is not of the +-- appropriate kind +isCoercionTyCon_maybe :: TyCon -> Maybe (Arity, [Type] -> (Type,Type)) +isCoercionTyCon_maybe (CoercionTyCon {tyConArity = ar, coKindFun = rule}) + = Just (ar, rule) +isCoercionTyCon_maybe _ = Nothing + +-- | Is this a 'TyCon' that represents a coercion? +isCoercionTyCon :: TyCon -> Bool +isCoercionTyCon (CoercionTyCon {}) = True +isCoercionTyCon _ = False + +-- | Identifies implicit tycons that, in particular, do not go into interface +-- files (because they are implicitly reconstructed when the interface is +-- read). +-- +-- Note that: +-- +-- * Associated families are implicit, as they are re-constructed from +-- the class declaration in which they reside, and +-- +-- * Family instances are /not/ implicit as they represent the instance body +-- (similar to a @dfun@ does that for a class instance). +isImplicitTyCon :: TyCon -> Bool +isImplicitTyCon tycon | isTyConAssoc tycon = True + | isSynTyCon tycon = False + | isAlgTyCon tycon = isClassTyCon tycon || + isTupleTyCon tycon +isImplicitTyCon _other = True + -- catches: FunTyCon, PrimTyCon, + -- CoercionTyCon, SuperKindTyCon \end{code} @@ -516,26 +937,32 @@ isForeignTyCon other = False \begin{code} tcExpandTyCon_maybe, coreExpandTyCon_maybe :: TyCon - -> [Type] -- Args to tycon - -> Maybe ([(TyVar,Type)], -- Substitution - Type, -- Body type (not yet substituted) - [Type]) -- Leftover args - --- For the *typechecker* view, we expand synonyms only -tcExpandTyCon_maybe (SynTyCon {tyConTyVars = tvs, synTcRhs = rhs }) tys + -> [Type] -- ^ Arguments to 'TyCon' + -> Maybe ([(TyVar,Type)], + Type, + [Type]) -- ^ Returns a 'TyVar' substitution, the body type + -- of the synonym (not yet substituted) and any arguments + -- remaining from the application + +-- ^ Used to create the view the /typechecker/ has on 'TyCon's. We expand (closed) synonyms only, cf. 'coreExpandTyCon_maybe' +tcExpandTyCon_maybe (SynTyCon {tyConTyVars = tvs, + synTcRhs = SynonymTyCon rhs }) tys = expand tvs rhs tys -tcExpandTyCon_maybe other_tycon tys = Nothing +tcExpandTyCon_maybe _ _ = Nothing --------------- --- For the *Core* view, we expand synonyms *and* non-recursive newtypes -coreExpandTyCon_maybe (AlgTyCon {algTcRec = NonRecursive, -- Not recursive - algTcRhs = NewTyCon { nt_etad_rhs = etad_rhs }}) tys + +-- ^ Used to create the view /Core/ has on 'TyCon's. We expand not only closed synonyms like 'tcExpandTyCon_maybe', +-- but also non-recursive @newtype@s +coreExpandTyCon_maybe (AlgTyCon { + algTcRhs = NewTyCon { nt_etad_rhs = etad_rhs, nt_co = Nothing }}) tys = case etad_rhs of -- Don't do this in the pattern match, lest we accidentally -- match the etad_rhs of a *recursive* newtype (tvs,rhs) -> expand tvs rhs tys - + coreExpandTyCon_maybe tycon tys = tcExpandTyCon_maybe tycon tys + ---------------- expand :: [TyVar] -> Type -- Template -> [Type] -- Args @@ -550,34 +977,39 @@ expand tvs rhs tys \end{code} \begin{code} +-- | Does this 'TyCon' have any generic to\/from functions available? See also 'hasGenerics' tyConHasGenerics :: TyCon -> Bool tyConHasGenerics (AlgTyCon {hasGenerics = hg}) = hg tyConHasGenerics (TupleTyCon {hasGenerics = hg}) = hg -tyConHasGenerics other = False -- Synonyms +tyConHasGenerics _ = False -- Synonyms +-- | As 'tyConDataCons_maybe', but returns the empty list of constructors if no constructors +-- could be found tyConDataCons :: TyCon -> [DataCon] -- It's convenient for tyConDataCons to return the -- empty list for type synonyms etc tyConDataCons tycon = tyConDataCons_maybe tycon `orElse` [] +-- | Determine the 'DataCon's originating from the given 'TyCon', if the 'TyCon' is the +-- sort that can have any constructors (note: this does not include abstract algebraic types) tyConDataCons_maybe :: TyCon -> Maybe [DataCon] tyConDataCons_maybe (AlgTyCon {algTcRhs = DataTyCon { data_cons = cons }}) = Just cons tyConDataCons_maybe (AlgTyCon {algTcRhs = NewTyCon { data_con = con }}) = Just [con] tyConDataCons_maybe (TupleTyCon {dataCon = con}) = Just [con] -tyConDataCons_maybe other = Nothing +tyConDataCons_maybe _ = Nothing +-- | Determine the number of value constructors a 'TyCon' has. Panics if the 'TyCon' +-- is not algebraic or a tuple tyConFamilySize :: TyCon -> Int -tyConFamilySize (AlgTyCon {algTcRhs = DataTyCon { data_cons = cons }}) = length cons -tyConFamilySize (AlgTyCon {algTcRhs = NewTyCon {}}) = 1 -tyConFamilySize (TupleTyCon {}) = 1 -#ifdef DEBUG +tyConFamilySize (AlgTyCon {algTcRhs = DataTyCon {data_cons = cons}}) = + length cons +tyConFamilySize (AlgTyCon {algTcRhs = NewTyCon {}}) = 1 +tyConFamilySize (AlgTyCon {algTcRhs = OpenTyCon {}}) = 0 +tyConFamilySize (TupleTyCon {}) = 1 tyConFamilySize other = pprPanic "tyConFamilySize:" (ppr other) -#endif - -tyConSelIds :: TyCon -> [Id] -tyConSelIds (AlgTyCon {algTcSelIds = fs}) = fs -tyConSelIds other_tycon = [] +-- | Extract an 'AlgTyConRhs' with information about data constructors from an algebraic or tuple +-- 'TyCon'. Panics for any other sort of 'TyCon' algTyConRhs :: TyCon -> AlgTyConRhs algTyConRhs (AlgTyCon {algTcRhs = rhs}) = rhs algTyConRhs (TupleTyCon {dataCon = con}) = DataTyCon { data_cons = [con], is_enum = False } @@ -585,67 +1017,122 @@ algTyConRhs other = pprPanic "algTyConRhs" (ppr other) \end{code} \begin{code} +-- | Extract the bound type variables and type expansion of a type synonym 'TyCon'. Panics if the +-- 'TyCon' is not a synonym newTyConRhs :: TyCon -> ([TyVar], Type) newTyConRhs (AlgTyCon {tyConTyVars = tvs, algTcRhs = NewTyCon { nt_rhs = rhs }}) = (tvs, rhs) newTyConRhs tycon = pprPanic "newTyConRhs" (ppr tycon) -newTyConRep :: TyCon -> ([TyVar], Type) -newTyConRep (AlgTyCon {tyConTyVars = tvs, algTcRhs = NewTyCon { nt_rep = rep }}) = (tvs, rep) -newTyConRep tycon = pprPanic "newTyConRep" (ppr tycon) +-- | Extract the bound type variables and type expansion of an eta-contracted type synonym 'TyCon'. +-- Panics if the 'TyCon' is not a synonym +newTyConEtadRhs :: TyCon -> ([TyVar], Type) +newTyConEtadRhs (AlgTyCon {algTcRhs = NewTyCon { nt_etad_rhs = tvs_rhs }}) = tvs_rhs +newTyConEtadRhs tycon = pprPanic "newTyConEtadRhs" (ppr tycon) + +-- | Extracts the @newtype@ coercion from such a 'TyCon', which can be used to construct something +-- with the @newtype@s type from its representation type (right hand side). If the supplied 'TyCon' +-- is not a @newtype@, returns @Nothing@ +newTyConCo_maybe :: TyCon -> Maybe TyCon +newTyConCo_maybe (AlgTyCon {algTcRhs = NewTyCon { nt_co = co }}) = co +newTyConCo_maybe _ = Nothing +-- | Find the primitive representation of a 'TyCon' tyConPrimRep :: TyCon -> PrimRep tyConPrimRep (PrimTyCon {primTyConRep = rep}) = rep tyConPrimRep tc = ASSERT(not (isUnboxedTupleTyCon tc)) PtrRep \end{code} \begin{code} +-- | Find the \"stupid theta\" of the 'TyCon'. A \"stupid theta\" is the context to the left of +-- an algebraic type declaration, e.g. @Eq a@ in the declaration @data Eq a => T a ...@ tyConStupidTheta :: TyCon -> [PredType] tyConStupidTheta (AlgTyCon {algTcStupidTheta = stupid}) = stupid tyConStupidTheta (TupleTyCon {}) = [] tyConStupidTheta tycon = pprPanic "tyConStupidTheta" (ppr tycon) \end{code} -@tyConArgVrcs_maybe@ gives a list of (occPos,occNeg) flags, one for -each tyvar, if available. See @calcAlgTyConArgVrcs@ for how this is -actually computed (in another file). - -\begin{code} -tyConArgVrcs :: TyCon -> ArgVrcs -tyConArgVrcs (FunTyCon {}) = [(False,True),(True,False)] -tyConArgVrcs (AlgTyCon {argVrcs = oi}) = oi -tyConArgVrcs (PrimTyCon {argVrcs = oi}) = oi -tyConArgVrcs (TupleTyCon {tyConArity = arity}) = (replicate arity (True,False)) -tyConArgVrcs (SynTyCon {argVrcs = oi}) = oi -\end{code} - \begin{code} +-- | Extract the 'TyVar's bound by a type synonym and the corresponding (unsubstituted) right hand side. +-- If the given 'TyCon' is not a type synonym, panics synTyConDefn :: TyCon -> ([TyVar], Type) -synTyConDefn (SynTyCon {tyConTyVars = tyvars, synTcRhs = ty}) = (tyvars,ty) +synTyConDefn (SynTyCon {tyConTyVars = tyvars, synTcRhs = SynonymTyCon ty}) + = (tyvars, ty) synTyConDefn tycon = pprPanic "getSynTyConDefn" (ppr tycon) -synTyConRhs :: TyCon -> Type -synTyConRhs tc = synTcRhs tc +-- | Extract the information pertaining to the right hand side of a type synonym (@type@) declaration. Panics +-- if the given 'TyCon' is not a type synonym +synTyConRhs :: TyCon -> SynTyConRhs +synTyConRhs (SynTyCon {synTcRhs = rhs}) = rhs +synTyConRhs tc = pprPanic "synTyConRhs" (ppr tc) + +-- | Find the expansion of the type synonym represented by the given 'TyCon'. The free variables of this +-- type will typically include those 'TyVar's bound by the 'TyCon'. Panics if the 'TyCon' is not that of +-- a type synonym +synTyConType :: TyCon -> Type +synTyConType tc = case synTcRhs tc of + SynonymTyCon t -> t + _ -> pprPanic "synTyConType" (ppr tc) + +-- | Find the 'Kind' of an open type synonym. Panics if the 'TyCon' is not an open type synonym +synTyConResKind :: TyCon -> Kind +synTyConResKind (SynTyCon {synTcRhs = OpenSynTyCon kind _}) = kind +synTyConResKind tycon = pprPanic "synTyConResKind" (ppr tycon) \end{code} \begin{code} -maybeTyConSingleCon :: TyCon -> Maybe DataCon -maybeTyConSingleCon (AlgTyCon {algTcRhs = DataTyCon {data_cons = [c] }}) = Just c -maybeTyConSingleCon (AlgTyCon {algTcRhs = NewTyCon { data_con = c }}) = Just c -maybeTyConSingleCon (AlgTyCon {}) = Nothing -maybeTyConSingleCon (TupleTyCon {dataCon = con}) = Just con -maybeTyConSingleCon (PrimTyCon {}) = Nothing -maybeTyConSingleCon (FunTyCon {}) = Nothing -- case at funty -maybeTyConSingleCon tc = pprPanic "maybeTyConSingleCon: unexpected tycon " $ ppr tc +-- | If the given 'TyCon' has a /single/ data constructor, i.e. it is a @data@ type with one +-- alternative, a tuple type or a @newtype@ then that constructor is returned. If the 'TyCon' +-- has more than one constructor, or represents a primitive or function type constructor then +-- @Nothing@ is returned. In any other case, the function panics +tyConSingleDataCon_maybe :: TyCon -> Maybe DataCon +tyConSingleDataCon_maybe (AlgTyCon {algTcRhs = DataTyCon {data_cons = [c] }}) = Just c +tyConSingleDataCon_maybe (AlgTyCon {algTcRhs = NewTyCon { data_con = c }}) = Just c +tyConSingleDataCon_maybe (AlgTyCon {}) = Nothing +tyConSingleDataCon_maybe (TupleTyCon {dataCon = con}) = Just con +tyConSingleDataCon_maybe (PrimTyCon {}) = Nothing +tyConSingleDataCon_maybe (FunTyCon {}) = Nothing -- case at funty +tyConSingleDataCon_maybe tc = pprPanic "tyConSingleDataCon_maybe: unexpected tycon " $ ppr tc \end{code} \begin{code} +-- | Is this 'TyCon' that for a class instance? isClassTyCon :: TyCon -> Bool -isClassTyCon (AlgTyCon {algTcClass = Just _}) = True -isClassTyCon other_tycon = False +isClassTyCon (AlgTyCon {algTcParent = ClassTyCon _}) = True +isClassTyCon _ = False +-- | If this 'TyCon' is that for a class instance, return the class it is for. +-- Otherwise returns @Nothing@ tyConClass_maybe :: TyCon -> Maybe Class -tyConClass_maybe (AlgTyCon {algTcClass = maybe_clas}) = maybe_clas -tyConClass_maybe ther_tycon = Nothing +tyConClass_maybe (AlgTyCon {algTcParent = ClassTyCon clas}) = Just clas +tyConClass_maybe _ = Nothing + +-- | Is this 'TyCon' that for a family instance, be that for a synonym or an +-- algebraic family instance? +isFamInstTyCon :: TyCon -> Bool +isFamInstTyCon (AlgTyCon {algTcParent = FamilyTyCon _ _ _ }) = True +isFamInstTyCon (SynTyCon {synTcParent = FamilyTyCon _ _ _ }) = True +isFamInstTyCon _ = False + +-- | If this 'TyCon' is that of a family instance, return the family in question +-- and the instance types. Otherwise, return @Nothing@ +tyConFamInst_maybe :: TyCon -> Maybe (TyCon, [Type]) +tyConFamInst_maybe (AlgTyCon {algTcParent = FamilyTyCon fam instTys _}) = + Just (fam, instTys) +tyConFamInst_maybe (SynTyCon {synTcParent = FamilyTyCon fam instTys _}) = + Just (fam, instTys) +tyConFamInst_maybe _ = + Nothing + +-- | If this 'TyCon' is that of a family instance, return a 'TyCon' which represents +-- a coercion identifying the representation type with the type instance family. +-- Otherwise, return @Nothing@ +tyConFamilyCoercion_maybe :: TyCon -> Maybe TyCon +tyConFamilyCoercion_maybe (AlgTyCon {algTcParent = FamilyTyCon _ _ coe}) = + Just coe +tyConFamilyCoercion_maybe (SynTyCon {synTcParent = FamilyTyCon _ _ coe}) = + Just coe +tyConFamilyCoercion_maybe _ = + Nothing \end{code}