X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2Ftypes%2FTyCon.lhs;h=958a0cb8a2b39d579ee4bd46b6d2f4d38539773e;hp=e6366bea2b01d9b2f9ff10fc938b984f5128cb82;hb=c56450419ef6c819ad86ab01dca6fd2966b11305;hpb=2fbab1a0f1a017799e8f5130bdf1078060623f29 diff --git a/compiler/types/TyCon.lhs b/compiler/types/TyCon.lhs index e6366be..958a0cb 100644 --- a/compiler/types/TyCon.lhs +++ b/compiler/types/TyCon.lhs @@ -7,64 +7,77 @@ The @TyCon@ datatype \begin{code} module TyCon( - TyCon, FieldLabel, - - PrimRep(..), - tyConPrimRep, - primRepSizeW, + -- * Main TyCon data types + TyCon, FieldLabel, CoTyConKindChecker, AlgTyConRhs(..), visibleDataCons, TyConParent(..), SynTyConRhs(..), + AssocFamilyPermutation, - isFunTyCon, isUnLiftedTyCon, isProductTyCon, - isAlgTyCon, isDataTyCon, - isNewTyCon, unwrapNewTyCon_maybe, - isSynTyCon, isClosedSynTyCon, isOpenSynTyCon, - isPrimTyCon, - - isEnumerationTyCon, isGadtSyntaxTyCon, isOpenTyCon, - assocTyConArgPoss_maybe, isTyConAssoc, setTyConArgPoss, - isTupleTyCon, isUnboxedTupleTyCon, isBoxedTupleTyCon, tupleTyConBoxity, - isRecursiveTyCon, newTyConRhs, newTyConEtadRhs, newTyConCo_maybe, - isHiBootTyCon, isSuperKindTyCon, - isCoercionTyCon_maybe, isCoercionTyCon, - isImplicitTyCon, - - tcExpandTyCon_maybe, coreExpandTyCon_maybe, - - makeTyConAbstract, isAbstractTyCon, - - mkForeignTyCon, isForeignTyCon, - + -- ** Constructing TyCons mkAlgTyCon, mkClassTyCon, mkFunTyCon, mkPrimTyCon, - mkVoidPrimTyCon, + mkKindTyCon, mkLiftedPrimTyCon, mkTupleTyCon, mkSynTyCon, mkSuperKindTyCon, mkCoercionTyCon, - + mkForeignTyCon, + mkAnyTyCon, + + -- ** Predicates on TyCons + isAlgTyCon, + isClassTyCon, isFamInstTyCon, + isFunTyCon, + isPrimTyCon, + isTupleTyCon, isUnboxedTupleTyCon, isBoxedTupleTyCon, + isSynTyCon, isClosedSynTyCon, isOpenSynTyCon, + isSuperKindTyCon, isDecomposableTyCon, + isCoercionTyCon, isCoercionTyCon_maybe, + isForeignTyCon, isAnyTyCon, tyConHasKind, + + isInjectiveTyCon, + isDataTyCon, isProductTyCon, isEnumerationTyCon, + isNewTyCon, isAbstractTyCon, isOpenTyCon, + isUnLiftedTyCon, + isGadtSyntaxTyCon, + isTyConAssoc, + isRecursiveTyCon, + isHiBootTyCon, + isImplicitTyCon, tyConHasGenerics, + + -- ** Extracting information out of TyCons tyConName, tyConKind, tyConUnique, tyConTyVars, - algTyConRhs, tyConDataCons, tyConDataCons_maybe, tyConFamilySize, - tyConSelIds, + tyConDataCons, tyConDataCons_maybe, tyConSingleDataCon_maybe, + tyConFamilySize, tyConStupidTheta, tyConArity, - isClassTyCon, tyConClass_maybe, - isFamInstTyCon, tyConFamInst_maybe, tyConFamilyCoercion_maybe, + 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" @@ -81,6 +94,7 @@ import Maybes import Outputable import FastString import Constants +import Data.List( elemIndex ) \end{code} %************************************************************************ @@ -90,201 +104,285 @@ import Constants %************************************************************************ \begin{code} +-- | TyCons represent 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, + tc_kind :: 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, + tc_kind :: Kind, tyConArity :: Arity, - tyConTyVars :: [TyVar], -- Scopes over (a) the algTcStupidTheta - -- (b) the cached types in - -- algTyConRhs.NewTyCon - -- (c) the family instance - -- types if present - -- But not over the data constructors - - algTcSelIds :: [Id], -- Its record selectors (empty if none) - - algTcGadtSyntax :: Bool, -- True <=> the data type was declared using GADT syntax - -- That doesn't mean it's a true GADT; only that the "where" + 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-printinng - algTcStupidTheta :: [PredType], -- The "stupid theta" for the data type - -- (always empty for GADTs) + -- 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, -- Data constructors in here + algTcRhs :: AlgTyConRhs, -- ^ Contains information about the data constructors of the algebraic type - algTcRec :: RecFlag, -- Tells whether the data type is part - -- of a mutually-recursive group or not + algTcRec :: RecFlag, -- ^ Tells us whether the data type is part of a mutually-recursive group or not - hasGenerics :: Bool, -- True <=> generic to/from functions are available - -- (in the exports of the data type's source module) + 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 tycon for - -- derived tycons representing classes - -- or family instances, respectively. + algTcParent :: TyConParent -- ^ Gives the class or family declaration 'TyCon' for derived 'TyCon's + -- representing class or family instances, respectively. See also 'synTcParent' } + -- | Represents the infinite family of tuple type constructors, @()@, @(a,b)@, @(# a, b #)@ etc. | TupleTyCon { tyConUnique :: Unique, tyConName :: Name, - tyConKind :: Kind, + tc_kind :: Kind, tyConArity :: Arity, tyConBoxed :: Boxity, tyConTyVars :: [TyVar], - dataCon :: DataCon, + dataCon :: DataCon, -- ^ Corresponding tuple data constructor hasGenerics :: Bool } + -- | Represents type synonyms | SynTyCon { tyConUnique :: Unique, tyConName :: Name, - tyConKind :: Kind, + tc_kind :: Kind, tyConArity :: Arity, tyConTyVars :: [TyVar], -- Bound tyvars - synTcRhs :: SynTyConRhs, -- Expanded type in here + synTcRhs :: SynTyConRhs, -- ^ Contains information about the expansion of the synonym - synTcParent :: TyConParent -- Gives the family tycon of - -- representation tycons of family - -- instances + synTcParent :: TyConParent -- ^ Gives the family declaration 'TyCon' of 'TyCon's representing family instances } - | PrimTyCon { -- Primitive types; cannot be defined in Haskell - -- Now includes foreign-imported types - -- Also includes Kinds + -- | 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, -- SLPJ Oct06: I'm not sure what the significance - -- of the arity of a primtycon is! + tc_kind :: Kind, + 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. + primTyConRep :: PrimRep, -- ^ Many primitive tycons are unboxed, but some are + -- boxed (represented by pointers). This 'PrimRep' holds + -- that information. + -- Only relevant if tc_kind = * - 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 } - | CoercionTyCon { -- E.g. (:=:), sym, trans, left, right - -- INVARIANT: coercions are always fully applied + -- | Type coercions, such as @(~)@, @sym@, @trans@, @left@ and @right@. + -- INVARIANT: Coercion TyCons are always fully applied + -- But note that a CoercionTyCon can be over-saturated in a type. + -- E.g. (sym g1) Int will be represented as (TyConApp sym [g1,Int]) + | CoercionTyCon { tyConUnique :: Unique, tyConName :: Name, tyConArity :: Arity, - coKindFun :: [Type] -> (Type,Type) - } -- INVARIANT: coKindFun is always applied to exactly 'arity' args - -- E.g. for trans (c1 :: ta=tb) (c2 :: tb=tc), the coKindFun returns - -- the kind as a pair of types: (ta,tc) - - | SuperKindTyCon { -- Super Kinds, TY (box) and CO (diamond). - -- They have no kind; and arity zero + coKindFun :: CoTyConKindChecker + } + + -- | Any types. Like tuples, this is a potentially-infinite family of TyCons + -- one for each distinct Kind. They have no values at all. + -- Because there are infinitely many of them (like tuples) they are + -- defined in GHC.Prim and have names like "Any(*->*)". + -- Their Unique is derived from the OccName. + -- See Note [Any types] in TysPrim + | AnyTyCon { + tyConUnique :: Unique, + tyConName :: Name, + tc_kind :: Kind -- Never = *; that is done via PrimTyCon + -- See Note [Any types] in TysPrim + } + + -- | 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 } +type CoTyConKindChecker = forall m. Monad m => CoTyConKindCheckerFun m + +type CoTyConKindCheckerFun m + = (Type -> m Kind) -- Kind checker for types + -> (Type -> m (Type,Type)) -- and for coercions + -> Bool -- True => apply consistency checks + -> [Type] -- Exactly right number of args + -> m (Type, Type) -- Kind of this application + + -- ^ Function that when given a list of the type arguments to the 'TyCon' + -- constructs the types that the resulting coercion relates. + -- Returns Nothing if ill-kinded. + -- + -- 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)@ + +-- | Names of the fields in an algebraic record type type FieldLabel = Name --- Right hand sides of type constructors for algebraic types --- +-- | Represents right-hand-sides of 'TyCon's for algebraic types data AlgTyConRhs - -- 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 - -- The constructor represents an open family without a fixed right hand + -- | 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 decl: - -- data T a :: * - -- or an assoicated data type decl, in a class decl: - -- class C a b where - -- data T b :: * + -- 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 :: Maybe [Int] - -- Nothing <=> top-level indexed type family - -- Just ns <=> associated (not toplevel) family - -- In the latter case, for each tyvar in the AT decl, 'ns' gives the - -- position of that tyvar in the class argument list (starting from 0). - -- NB: Length is less than tyConArity iff higher kind signature. - + 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 + -- + -- INVARIANT: Kept in order of increasing 'DataCon' tag + -- (see the tag assignment in DataCon.mkDataCon) - is_enum :: Bool -- Cached: True <=> an enumeration type - } -- Includes data types with no constructors. + 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 - -- The free tyvars of this type are the tyConTyVars + 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 CoercionTyCon used to create the newtype - -- from the representation - -- Optional for non-recursive newtypes + 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. - - 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] } +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 +-- ^ 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 tycons. - +-- 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 - = NoParentTyCon -- An ordinary type constructor has no parent. + = -- | An ordinary type constructor has no parent. + NoParentTyCon - | ClassTyCon -- Type constructors representing a class dictionary. + -- | Type constructors representing a class dictionary. + | ClassTyCon Class -- INVARIANT: the classTyCon of this Class is the current tycon - | FamilyTyCon -- Type constructors representing an instance of a type - TyCon -- The type family - [Type] -- 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 - TyCon -- A CoercionTyCon identifying the representation - -- type with the type instance family. - -- c.f. Note [Newtype coercions] + -- | 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] = ... @@ -293,24 +391,24 @@ data TyConParent -- axiom co a :: T [a] ~ :R7T a -- with :R7T's algTcParent = FamilyTyCon T [a] co -okParent :: Name -> TyConParent -> Bool -- Checks invariants +-- | 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 Kind -- Type family: *result* kind given - (Maybe [Int]) -- for associated families: for each tyvars in - -- the AT decl, gives the position of that - -- tyvar in the class argument list (starting - -- from 0). - -- NB: Length is less than tyConArity - -- if higher kind signature. - - | SynonymTyCon Type -- Mentioning head type vars. Acts as a template for - -- the expansion when the tycon is applied to some - -- types. + = 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] @@ -321,7 +419,7 @@ 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 -> +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 @@ -331,11 +429,11 @@ ending with the same type variables as the left hand side, we newtype S a = MkT [a] -then we would generate the arity 0 coercion CoS : S :=: []. The +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]) + 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]) @@ -346,7 +444,7 @@ 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] + axiom CoT t : T t ~ [t] Note [Newtype eta] ~~~~~~~~~~~~~~~~~~ @@ -426,12 +524,8 @@ Then %* * %************************************************************************ -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 +MachRep (see cmm/CmmExpr), although each of these types has a distinct and clearly defined purpose: - A PrimRep is a CgRep + information about signedness + information @@ -445,14 +539,17 @@ 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 ) @@ -460,7 +557,7 @@ data PrimRep instance Outputable PrimRep where ppr r = text (show r) --- Size of a PrimRep, in words +-- | Find the size of a 'PrimRep', in words primRepSizeW :: PrimRep -> Int primRepSizeW IntRep = 1 primRepSizeW WordRep = 1 @@ -486,55 +583,63 @@ 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 { tyConUnique = nameUnique name, tyConName = name, - tyConKind = kind, + tc_kind = 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) +-- | 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 - -> [TyVar] - -> [PredType] - -> AlgTyConRhs - -> [Id] + -> 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 - -> Bool - -> Bool + -> 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 sel_ids parent is_rec gen_info gadt_syn +mkAlgTyCon name kind tyvars stupid rhs parent is_rec gen_info gadt_syn = AlgTyCon { tyConName = name, tyConUnique = nameUnique name, - tyConKind = kind, + tc_kind = kind, tyConArity = length tyvars, tyConTyVars = tyvars, algTcStupidTheta = stupid, algTcRhs = rhs, - algTcSelIds = sel_ids, algTcParent = ASSERT( okParent name parent ) parent, algTcRec = is_rec, algTcGadtSyntax = gadt_syn, hasGenerics = gen_info } +-- | 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 -> Arity -> [TyVar] -> DataCon -> Boxity -> Bool -> TyCon + 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, tyConName = name, - tyConKind = kind, + tc_kind = kind, tyConArity = arity, tyConBoxed = boxed, tyConTyVars = tyvars, @@ -542,16 +647,20 @@ 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 -> Maybe FastString -> Kind -> Arity -> TyCon +-- ^ 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, + tc_kind = kind, tyConArity = arity, primTyConRep = PtrRep, -- they all do isUnLifted = False, @@ -559,16 +668,17 @@ mkForeignTyCon name ext_name kind arity } --- most Prim tycons are lifted +-- | 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 -mkVoidPrimTyCon :: Name -> Kind -> Arity -> TyCon -mkVoidPrimTyCon name kind arity - = mkPrimTyCon' name kind arity VoidRep True +-- | Kind constructors +mkKindTyCon :: Name -> Kind -> TyCon +mkKindTyCon name kind + = mkPrimTyCon' name kind 0 VoidRep True --- but RealWorld is lifted +-- | 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 @@ -578,36 +688,52 @@ mkPrimTyCon' name kind arity rep is_unlifted = PrimTyCon { tyConName = name, tyConUnique = nameUnique name, - tyConKind = kind, + tc_kind = kind, tyConArity = arity, primTyConRep = rep, isUnLifted = is_unlifted, tyConExtName = Nothing } +-- | Create a type synonym 'TyCon' mkSynTyCon :: Name -> Kind -> [TyVar] -> SynTyConRhs -> TyConParent -> TyCon mkSynTyCon name kind tyvars rhs parent = SynTyCon { tyConName = name, tyConUnique = nameUnique name, - tyConKind = kind, + tc_kind = kind, tyConArity = length tyvars, tyConTyVars = tyvars, synTcRhs = rhs, synTcParent = parent } -mkCoercionTyCon :: Name -> Arity -> ([Type] -> (Type,Type)) -> TyCon -mkCoercionTyCon name arity kindRule +-- | Create a coercion 'TyCon' +mkCoercionTyCon :: Name -> Arity + -> CoTyConKindChecker + -> TyCon +mkCoercionTyCon name arity rule_fn = CoercionTyCon { - tyConName = name, + tyConName = name, tyConUnique = nameUnique name, - tyConArity = arity, - coKindFun = kindRule + tyConArity = arity, +#ifdef DEBUG + coKindFun = \ ty co fail args -> + ASSERT2( length args == arity, ppr name ) + rule_fn ty co fail args +#else + coKindFun = rule_fn +#endif } --- Super kinds always have arity zero -mkSuperKindTyCon :: Name -> TyCon +mkAnyTyCon :: Name -> Kind -> TyCon +mkAnyTyCon name kind + = AnyTyCon { tyConName = name, + tc_kind = kind, + tyConUnique = nameUnique name } + +-- | Create a super-kind 'TyCon' +mkSuperKindTyCon :: Name -> TyCon -- Super kinds always have arity zero mkSuperKindTyCon name = SuperKindTyCon { tyConName = name, @@ -620,42 +746,45 @@ 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 _ = False isDataTyCon :: TyCon -> Bool --- isDataTyCon returns True for data types that are definitely --- 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 --- type families +-- ^ 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. -- --- NB: for a data type family, T, only the *instance* tycons are --- get an info table etc. The family tycon does not. --- Hence False for OpenTyCon +-- 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 @@ -665,10 +794,19 @@ isDataTyCon (AlgTyCon {algTcRhs = rhs}) isDataTyCon (TupleTyCon {tyConBoxed = boxity}) = isBoxed boxity isDataTyCon _ = False +-- | Is this 'TyCon' that for a @newtype@ isNewTyCon :: TyCon -> Bool isNewTyCon (AlgTyCon {algTcRhs = NewTyCon {}}) = True isNewTyCon _ = False +tyConHasKind :: TyCon -> Bool +tyConHasKind (SuperKindTyCon {}) = False +tyConHasKind (CoercionTyCon {}) = False +tyConHasKind _ = True + +-- | 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, @@ -677,14 +815,14 @@ unwrapNewTyCon_maybe (AlgTyCon { tyConTyVars = tvs, unwrapNewTyCon_maybe _ = Nothing isProductTyCon :: TyCon -> Bool --- A "product" tycon --- has *one* constructor, --- is *not* existential --- but --- may be DataType, 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 @@ -693,6 +831,7 @@ isProductTyCon tc@(AlgTyCon {}) = case algTcRhs tc of isProductTyCon (TupleTyCon {}) = True isProductTyCon _ = False +-- | Is this a 'TyCon' representing a type synonym (@type@)? isSynTyCon :: TyCon -> Bool isSynTyCon (SynTyCon {}) = True isSynTyCon _ = False @@ -701,102 +840,159 @@ isSynTyCon _ = False -- 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 +isDecomposableTyCon :: TyCon -> Bool +-- True iff we can deocmpose (T a b c) into ((T a b) c) +-- Specifically NOT true of synonyms (open and otherwise) and coercions +isDecomposableTyCon (SynTyCon {}) = False +isDecomposableTyCon (CoercionTyCon {}) = False +isDecomposableTyCon _other = True + +-- | 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 (TupleTyCon {tyConArity = arity}) = arity == 0 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 +isOpenTyCon (SynTyCon {synTcRhs = OpenSynTyCon {}}) = True +isOpenTyCon (AlgTyCon {algTcRhs = OpenTyCon {}}) = True +isOpenTyCon _ = False + +-- | Injective 'TyCon's can be decomposed, so that +-- T ty1 ~ T ty2 => ty1 ~ ty2 +isInjectiveTyCon :: TyCon -> Bool +isInjectiveTyCon tc = not (isSynTyCon tc) + -- Ultimately we may have injective associated types + -- in which case this test will become more interesting + -- + -- It'd be unusual to call isInjectiveTyCon on a regular H98 + -- type synonym, because you should probably have expanded it first + -- But regardless, it's not injective! +-- | 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 -setTyConArgPoss :: TyCon -> [Int] -> TyCon -setTyConArgPoss tc@(AlgTyCon { algTcRhs = rhs }) poss = - tc { algTcRhs = rhs {otArgPoss = Just poss} } -setTyConArgPoss tc@(SynTyCon { synTcRhs = OpenSynTyCon ki _ }) poss = - tc { synTcRhs = OpenSynTyCon ki (Just poss) } -setTyConArgPoss tc _ = pprPanic "setTyConArgPoss" (ppr tc) +-- | 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 _ = False +-- | Is this the 'TyCon' for an unboxed tuple? isUnboxedTupleTyCon :: TyCon -> Bool isUnboxedTupleTyCon (TupleTyCon {tyConBoxed = boxity}) = not (isBoxed boxity) isUnboxedTupleTyCon _ = False +-- | Is this the 'TyCon' for a boxed tuple? isBoxedTupleTyCon :: TyCon -> Bool isBoxedTupleTyCon (TupleTyCon {tyConBoxed = boxity}) = isBoxed boxity 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 _ = 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 _ = 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 _ = False +-- | Is this a super-kind 'TyCon'? isSuperKindTyCon :: TyCon -> Bool isSuperKindTyCon (SuperKindTyCon {}) = True isSuperKindTyCon _ = False -isCoercionTyCon_maybe :: TyCon -> Maybe (Arity, [Type] -> (Type,Type)) +-- | Is this an AnyTyCon? +isAnyTyCon :: TyCon -> Bool +isAnyTyCon (AnyTyCon {}) = True +isAnyTyCon _ = 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 :: Monad m => TyCon -> Maybe (Arity, CoTyConKindCheckerFun m) 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 +-- | Identifies implicit tycons that, in particular, do not go into interface -- files (because they are implicitly reconstructed when the interface is -- read). -- --- Note that +-- Note that: -- --- * associated families are implicit, as they are re-constructed from +-- * 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). -- +-- * 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 @@ -815,21 +1011,24 @@ isImplicitTyCon _other = True \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 (closed) synonyms only + -> [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 _ _ = Nothing --------------- --- For the *Core* view, we expand synonyms only as well -coreExpandTyCon_maybe (AlgTyCon {algTcRec = NonRecursive, -- Not recursive +-- ^ 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 @@ -852,22 +1051,38 @@ 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 _ = False -- Synonyms +tyConKind :: TyCon -> Kind +tyConKind (FunTyCon { tc_kind = k }) = k +tyConKind (AlgTyCon { tc_kind = k }) = k +tyConKind (TupleTyCon { tc_kind = k }) = k +tyConKind (SynTyCon { tc_kind = k }) = k +tyConKind (PrimTyCon { tc_kind = k }) = k +tyConKind (AnyTyCon { tc_kind = k }) = k +tyConKind tc = pprPanic "tyConKind" (ppr tc) + +-- | 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 _ = 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 @@ -876,35 +1091,44 @@ tyConFamilySize (AlgTyCon {algTcRhs = OpenTyCon {}}) = 0 tyConFamilySize (TupleTyCon {}) = 1 tyConFamilySize other = pprPanic "tyConFamilySize:" (ppr other) -tyConSelIds :: TyCon -> [Id] -tyConSelIds (AlgTyCon {algTcSelIds = fs}) = fs -tyConSelIds _ = [] - +-- | 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 } +algTyConRhs (AlgTyCon {algTcRhs = rhs}) = rhs +algTyConRhs (TupleTyCon {dataCon = con, tyConArity = arity}) + = DataTyCon { data_cons = [con], is_enum = arity == 0 } 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) +-- | 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 {}) = [] @@ -912,50 +1136,66 @@ tyConStupidTheta tycon = pprPanic "tyConStupidTheta" (ppr tycon) \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 = SynonymTyCon ty}) = (tyvars, ty) synTyConDefn tycon = pprPanic "getSynTyConDefn" (ppr tycon) +-- | 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 (TupleTyCon {dataCon = c}) = Just c +tyConSingleDataCon_maybe (AlgTyCon {algTcRhs = DataTyCon { data_cons = [c] }}) = Just c +tyConSingleDataCon_maybe (AlgTyCon {algTcRhs = NewTyCon { data_con = c }}) = Just c +tyConSingleDataCon_maybe _ = Nothing \end{code} \begin{code} +-- | Is this 'TyCon' that for a class instance? isClassTyCon :: TyCon -> Bool 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 {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) @@ -964,6 +1204,9 @@ tyConFamInst_maybe (SynTyCon {synTcParent = FamilyTyCon 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