X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2Fprelude%2FTysPrim.lhs;h=4e1576f9f0f2d2cbbbdf2e6476f99a68d3560bcc;hp=c69bea12b1ffda115982597b709a8380b310b991;hb=388e3356f71daffa62f1d4157e1e07e4c68f218a;hpb=c173e8d155ca61ec53224c39d8cb936ddcc5dbda diff --git a/compiler/prelude/TysPrim.lhs b/compiler/prelude/TysPrim.lhs index c69bea1..4e1576f 100644 --- a/compiler/prelude/TysPrim.lhs +++ b/compiler/prelude/TysPrim.lhs @@ -1,9 +1,13 @@ % % (c) The AQUA Project, Glasgow University, 1994-1998 % + + \section[TysPrim]{Wired-in knowledge about primitive types} \begin{code} +-- | This module defines TyCons that can't be expressed in Haskell. +-- They are all, therefore, wired-in TyCons. C.f module TysWiredIn module TysPrim( alphaTyVars, betaTyVars, alphaTyVar, betaTyVar, gammaTyVar, deltaTyVar, alphaTy, betaTy, gammaTy, deltaTy, @@ -41,20 +45,21 @@ module TysPrim( int64PrimTyCon, int64PrimTy, word64PrimTyCon, word64PrimTy, - anyPrimTyCon, anyPrimTy, anyPrimTyCon1, mkAnyPrimTyCon + -- * Any + anyTyCon, anyType, anyTyConOfKind, anyTypeOfKind ) where #include "HsVersions.h" import Var ( TyVar, mkTyVar ) import Name ( Name, BuiltInSyntax(..), mkInternalName, mkWiredInName ) +import OccName ( mkTcOcc ) import OccName ( mkTyVarOccFS, mkTcOccFS ) -import TyCon ( TyCon, mkPrimTyCon, mkLiftedPrimTyCon ) +import TyCon ( TyCon, mkPrimTyCon, mkLiftedPrimTyCon, mkAnyTyCon ) import Type import SrcLoc -import Unique ( mkAlphaTyVarUnique, pprUnique ) +import Unique ( mkAlphaTyVarUnique ) import PrelNames -import StaticFlags import FastString import Outputable @@ -94,7 +99,7 @@ primTyCons , wordPrimTyCon , word32PrimTyCon , word64PrimTyCon - , anyPrimTyCon, anyPrimTyCon1 + , anyTyCon ] mkPrimTc :: FastString -> Unique -> TyCon -> Name @@ -104,7 +109,7 @@ mkPrimTc fs unique tycon (ATyCon tycon) -- Relevant TyCon UserSyntax -- None are built-in syntax -charPrimTyConName, intPrimTyConName, int32PrimTyConName, int64PrimTyConName, wordPrimTyConName, word32PrimTyConName, word64PrimTyConName, addrPrimTyConName, floatPrimTyConName, doublePrimTyConName, statePrimTyConName, realWorldTyConName, arrayPrimTyConName, byteArrayPrimTyConName, mutableArrayPrimTyConName, mutableByteArrayPrimTyConName, mutVarPrimTyConName, mVarPrimTyConName, tVarPrimTyConName, stablePtrPrimTyConName, stableNamePrimTyConName, bcoPrimTyConName, weakPrimTyConName, threadIdPrimTyConName, anyPrimTyConName, anyPrimTyCon1Name :: Name +charPrimTyConName, intPrimTyConName, int32PrimTyConName, int64PrimTyConName, wordPrimTyConName, word32PrimTyConName, word64PrimTyConName, addrPrimTyConName, floatPrimTyConName, doublePrimTyConName, statePrimTyConName, realWorldTyConName, arrayPrimTyConName, byteArrayPrimTyConName, mutableArrayPrimTyConName, mutableByteArrayPrimTyConName, mutVarPrimTyConName, mVarPrimTyConName, tVarPrimTyConName, stablePtrPrimTyConName, stableNamePrimTyConName, bcoPrimTyConName, weakPrimTyConName, threadIdPrimTyConName :: Name charPrimTyConName = mkPrimTc (fsLit "Char#") charPrimTyConKey charPrimTyCon intPrimTyConName = mkPrimTc (fsLit "Int#") intPrimTyConKey intPrimTyCon int32PrimTyConName = mkPrimTc (fsLit "Int32#") int32PrimTyConKey int32PrimTyCon @@ -129,8 +134,6 @@ stableNamePrimTyConName = mkPrimTc (fsLit "StableName#") stableNamePrimTyC bcoPrimTyConName = mkPrimTc (fsLit "BCO#") bcoPrimTyConKey bcoPrimTyCon weakPrimTyConName = mkPrimTc (fsLit "Weak#") weakPrimTyConKey weakPrimTyCon threadIdPrimTyConName = mkPrimTc (fsLit "ThreadId#") threadIdPrimTyConKey threadIdPrimTyCon -anyPrimTyConName = mkPrimTc (fsLit "Any") anyPrimTyConKey anyPrimTyCon -anyPrimTyCon1Name = mkPrimTc (fsLit "Any1") anyPrimTyCon1Key anyPrimTyCon1 \end{code} %************************************************************************ @@ -182,6 +185,115 @@ openBetaTy = mkTyVarTy openBetaTyVar %************************************************************************ %* * + Any +%* * +%************************************************************************ + +Note [Any types] +~~~~~~~~~~~~~~~~ +The type constructor Any::* has these properties + + * It is defined in module GHC.Prim, and exported so that it is + available to users. For this reason it's treated like any other + primitive type: + - has a fixed unique, anyTyConKey, + - lives in the global name cache + - built with TyCon.PrimTyCon + + * It is lifted, and hence represented by a pointer + + * It is inhabited by at least one value, namely bottom + + * You can unsafely coerce any lifted type to Ayny, and back. + + * It does not claim to be a *data* type, and that's important for + the code generator, because the code gen may *enter* a data value + but never enters a function value. + + * It is used to instantiate otherwise un-constrained type variables of kind * + For example length Any [] + See Note [Strangely-kinded void TyCons] + +In addition, we have a potentially-infinite family of types, one for +each kind /other than/ *, needed to instantiate otherwise +un-constrained type variables of kinds other than *. This is a bit +like tuples; there is a potentially-infinite family. They have slightly +different characteristics to Any::*: + + * They are built with TyCon.AnyTyCon + * They have non-user-writable names like "Any(*->*)" + * They are not exported by GHC.Prim + * They are uninhabited (of course; not kind *) + * They have a unique derived from their OccName (see Note [Uniques of Any]) + * Their Names do not live in the global name cache + +Note [Uniques of Any] +~~~~~~~~~~~~~~~~~~~~~ +Although Any(*->*), say, doesn't have a binding site, it still needs +to have a Unique. Unlike tuples (which are also an infinite family) +there is no convenient way to index them, so we use the Unique from +their OccName instead. That should be unique! (But in principle we +must take care: it does not include the module/package.) + +Note [Strangely-kinded void TyCons] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +See Trac #959 for more examples + +When the type checker finds a type variable with no binding, which +means it can be instantiated with an arbitrary type, it usually +instantiates it to Void. Eg. + + length [] +===> + length Any (Nil Any) + +But in really obscure programs, the type variable might have a kind +other than *, so we need to invent a suitably-kinded type. + +This commit uses + Any for kind * + Any(*->*) for kind *->* + etc + +\begin{code} +anyTyConName :: Name +anyTyConName = mkPrimTc (fsLit "Any") anyTyConKey anyTyCon + +anyTyCon :: TyCon +anyTyCon = mkLiftedPrimTyCon anyTyConName liftedTypeKind 0 PtrRep + +anyType :: Type +anyType = mkTyConApp anyTyCon [] + +anyTypeOfKind :: Kind -> Type +anyTypeOfKind kind + | isLiftedTypeKind kind = anyType + | otherwise = mkTyConApp (mk_any_tycon kind) [] + +anyTyConOfKind :: Kind -> TyCon +anyTyConOfKind kind + | isLiftedTypeKind kind = anyTyCon + | otherwise = mk_any_tycon kind + +mk_any_tycon :: Kind -> TyCon +mk_any_tycon kind -- Kind other than * + = tycon + where + -- Derive the name from the kind, thus: + -- Any(*->*), Any(*->*->*) + -- These are names that can't be written by the user, + -- and are not allocated in the global name cache + str = "Any" ++ showSDoc (pprParendKind kind) + + occ = mkTcOcc str + uniq = getUnique occ -- See Note [Uniques of Any] + name = mkWiredInName gHC_PRIM occ uniq (ATyCon tycon) UserSyntax + tycon = mkAnyTyCon name kind +\end{code} + + +%************************************************************************ +%* * \subsection[TysPrim-basic]{Basic primitive types (@Char#@, @Int#@, etc.)} %* * %************************************************************************ @@ -294,54 +406,6 @@ defined in \tr{TysWiredIn.lhs}, not here. %************************************************************************ %* * - Any -%* * -%************************************************************************ - -The type constructor Any is type to which you can unsafely coerce any -lifted type, and back. - - * It is lifted, and hence represented by a pointer - - * It does not claim to be a *data* type, and that's important for - the code generator, because the code gen may *enter* a data value - but never enters a function value. - -It's also used to instantiate un-constrained type variables after type -checking. For example - length Any [] -Annoyingly, we sometimes need Anys of other kinds, such as (*->*) etc. -This is a bit like tuples. We define a couple of useful ones here, -and make others up on the fly. If any of these others end up being exported -into interface files, we'll get a crash; at least until we add interface-file -syntax to support them. - -\begin{code} -anyPrimTy :: Type -anyPrimTy = mkTyConApp anyPrimTyCon [] - -anyPrimTyCon :: TyCon -- Kind * -anyPrimTyCon = mkLiftedPrimTyCon anyPrimTyConName liftedTypeKind 0 PtrRep - -anyPrimTyCon1 :: TyCon -- Kind *->* -anyPrimTyCon1 = mkLiftedPrimTyCon anyPrimTyCon1Name kind 0 PtrRep - where - kind = mkArrowKind liftedTypeKind liftedTypeKind - -mkAnyPrimTyCon :: Unique -> Kind -> TyCon --- Grotesque hack alert: the client gives the unique; so equality won't work -mkAnyPrimTyCon unique kind - = WARN( opt_PprStyle_Debug, ptext (sLit "Urk! Inventing strangely-kinded Any TyCon:") <+> ppr unique <+> ppr kind ) - -- See Note [Strangely-kinded void TyCons] in TcHsSyn - tycon - where - name = mkPrimTc (mkFastString ("Any" ++ showSDoc (pprUnique unique))) unique tycon - tycon = mkLiftedPrimTyCon name kind 0 PtrRep -\end{code} - - -%************************************************************************ -%* * \subsection[TysPrim-arrays]{The primitive array types} %* * %************************************************************************