%
-% (c) The AQUA Project, Glasgow University, 1994-1996
+% (c) The AQUA Project, Glasgow University, 1994-1998
%
\section[TysPrim]{Wired-in knowledge about primitive types}
types and operations.''
\begin{code}
-module TysPrim where
+module TysPrim(
+ alphaTyVars, alphaTyVar, betaTyVar, gammaTyVar, deltaTyVar,
+ alphaTy, betaTy, gammaTy, deltaTy,
+ openAlphaTyVar, openAlphaTyVars,
+
+ charPrimTyCon, charPrimTy,
+ intPrimTyCon, intPrimTy,
+ wordPrimTyCon, wordPrimTy,
+ addrPrimTyCon, addrPrimTy,
+ floatPrimTyCon, floatPrimTy,
+ doublePrimTyCon, doublePrimTy,
+
+ statePrimTyCon, mkStatePrimTy,
+ realWorldTyCon, realWorldTy, realWorldStatePrimTy,
+
+ arrayPrimTyCon, mkArrayPrimTy,
+ byteArrayPrimTyCon, byteArrayPrimTy,
+ mutableArrayPrimTyCon, mkMutableArrayPrimTy,
+ mutableByteArrayPrimTyCon, mkMutableByteArrayPrimTy,
+ mutVarPrimTyCon, mkMutVarPrimTy,
+
+ mVarPrimTyCon, mkMVarPrimTy,
+ stablePtrPrimTyCon, mkStablePtrPrimTy,
+ weakPrimTyCon, mkWeakPrimTy,
+ foreignObjPrimTyCon, foreignObjPrimTy,
+ threadIdPrimTyCon, threadIdPrimTy,
+
+ int64PrimTyCon, int64PrimTy,
+ word64PrimTyCon, word64PrimTy,
+
+ primRepTyCon,
+
+ pcPrimTyCon
+ ) where
#include "HsVersions.h"
-import Kind ( mkBoxedTypeKind )
+import Var ( TyVar, mkSysTyVar )
import Name ( mkWiredInTyConName )
-import PrimRep ( PrimRep(..) ) -- getPrimRepInfo uses PrimRep repn
-import TyCon ( mkPrimTyCon, mkDataTyCon, TyCon )
-import BasicTypes ( NewOrData(..), RecFlag(..) )
-import Type ( mkTyConApp, mkTyConTy, mkTyVarTys, Type )
-import TyVar ( GenTyVar(..), alphaTyVars )
+import PrimRep ( PrimRep(..), isFollowableRep )
+import TyCon ( mkPrimTyCon, TyCon )
+import Type ( Type,
+ mkTyConApp, mkTyConTy, mkTyVarTys,
+ unboxedTypeKind, boxedTypeKind, openTypeKind, mkArrowKinds
+ )
import PrelMods ( pREL_GHC )
+import Outputable
import Unique
\end{code}
\begin{code}
+alphaTyVars :: [TyVar]
+alphaTyVars = [ mkSysTyVar u boxedTypeKind
+ | u <- map mkAlphaTyVarUnique [2..] ]
+
+alphaTyVar, betaTyVar, gammaTyVar :: TyVar
+(alphaTyVar:betaTyVar:gammaTyVar:deltaTyVar:_) = alphaTyVars
+
alphaTys = mkTyVarTys alphaTyVars
(alphaTy:betaTy:gammaTy:deltaTy:_) = alphaTys
+
+ -- openAlphaTyVar is prepared to be instantiated
+ -- to a boxed or unboxed type variable. It's used for the
+ -- result type for "error", so that we can have (error Int# "Help")
+openAlphaTyVar :: TyVar
+openAlphaTyVar = mkSysTyVar (mkAlphaTyVarUnique 1) openTypeKind
+
+openAlphaTyVars :: [TyVar]
+openAlphaTyVars = [ mkSysTyVar u openTypeKind
+ | u <- map mkAlphaTyVarUnique [2..] ]
\end{code}
%************************************************************************
\begin{code}
-- only used herein
pcPrimTyCon :: Unique{-TyConKey-} -> FAST_STRING -> Int -> PrimRep -> TyCon
-
-pcPrimTyCon key str arity primrep
+pcPrimTyCon key str arity rep
= the_tycon
where
name = mkWiredInTyConName key pREL_GHC str the_tycon
- the_tycon = mkPrimTyCon name arity primrep
-
+ the_tycon = mkPrimTyCon name kind arity rep
+ kind = mkArrowKinds (take arity (repeat openTypeKind)) result_kind
+ result_kind | isFollowableRep rep = boxedTypeKind -- Represented by a GC-ish ptr
+ | otherwise = unboxedTypeKind -- Represented by a non-ptr
charPrimTy = mkTyConTy charPrimTyCon
charPrimTyCon = pcPrimTyCon charPrimTyConKey SLIT("Char#") 0 CharRep
doublePrimTyCon = pcPrimTyCon doublePrimTyConKey SLIT("Double#") 0 DoubleRep
\end{code}
-@PrimitiveKinds@ are used in @PrimitiveOps@, for which we often need
-to reconstruct various type information. (It's slightly more
-convenient/efficient to make type info from kinds, than kinds [etc.]
-from type info.)
-
-\begin{code}
-getPrimRepInfo ::
- PrimRep -> (String, -- tag string
- Type, TyCon) -- prim type and tycon
-
-getPrimRepInfo CharRep = ("Char", charPrimTy, charPrimTyCon)
-getPrimRepInfo IntRep = ("Int", intPrimTy, intPrimTyCon)
-getPrimRepInfo WordRep = ("Word", wordPrimTy, wordPrimTyCon)
-getPrimRepInfo AddrRep = ("Addr", addrPrimTy, addrPrimTyCon)
-getPrimRepInfo FloatRep = ("Float", floatPrimTy, floatPrimTyCon)
-getPrimRepInfo DoubleRep = ("Double", doublePrimTy, doublePrimTyCon)
-getPrimRepInfo Int64Rep = ("Int64", int64PrimTy, int64PrimTyCon)
-getPrimRepInfo Word64Rep = ("Word64", word64PrimTy, word64PrimTyCon)
-getPrimRepInfo StablePtrRep = ("StablePtr", mkStablePtrPrimTy alphaTy, stablePtrPrimTyCon)
-getPrimRepInfo ForeignObjRep = ("ForeignObj", foreignObjPrimTy, foreignObjPrimTyCon)
-
-\end{code}
%************************************************************************
%* *
\end{code}
@_RealWorld@ is deeply magical. It {\em is primitive}, but it
-{\em is not unboxed}.
+{\em is not unboxed} (hence PtrRep).
We never manipulate values of type RealWorld; it's only used in the type
system, to parameterise State#.
\begin{code}
realWorldTy = mkTyConTy realWorldTyCon
-realWorldTyCon = mk_no_constr_tycon realWorldTyConKey SLIT("RealWorld")
+realWorldTyCon = pcPrimTyCon realWorldTyConKey SLIT("RealWorld") 0 PtrRep
realWorldStatePrimTy = mkStatePrimTy realWorldTy
\end{code}
Note: the ``state-pairing'' types are not truly primitive, so they are
defined in \tr{TysWiredIn.lhs}, not here.
-\begin{code}
--- The Void type is represented as a data type with no constructors
--- It's a built in type (i.e. there's no way to define it in Haskell;
--- the nearest would be
---
--- data Void = -- No constructors!
---
--- ) It's boxed; there is only one value of this
--- type, namely "void", whose semantics is just bottom.
-voidTy = mkTyConTy voidTyCon
-voidTyCon = mk_no_constr_tycon voidTyConKey SLIT("Void")
-\end{code}
-
-\begin{code}
-mk_no_constr_tycon key str
- = the_tycon
- where
- name = mkWiredInTyConName key pREL_GHC str the_tycon
- the_tycon = mkDataTyCon name mkBoxedTypeKind
- [] -- No tyvars
- [] -- No context
- [] -- No constructors; we tell you *nothing* about this guy
- [] -- No derivings
- Nothing -- Not a dictionary
- DataType
- NonRecursive
-\end{code}
%************************************************************************
%* *
%************************************************************************
%* *
+\subsection[TysPrim-mut-var]{The mutable variable type}
+%* *
+%************************************************************************
+
+\begin{code}
+mutVarPrimTyCon = pcPrimTyCon mutVarPrimTyConKey SLIT("MutVar#") 2 PtrRep
+
+mkMutVarPrimTy s elt = mkTyConApp mutVarPrimTyCon [s, elt]
+\end{code}
+
+%************************************************************************
+%* *
\subsection[TysPrim-synch-var]{The synchronizing variable type}
%* *
%************************************************************************
\begin{code}
-synchVarPrimTyCon = pcPrimTyCon synchVarPrimTyConKey SLIT("SynchVar#") 2 PtrRep
+mVarPrimTyCon = pcPrimTyCon mVarPrimTyConKey SLIT("MVar#") 2 PtrRep
-mkSynchVarPrimTy s elt = mkTyConApp synchVarPrimTyCon [s, elt]
+mkMVarPrimTy s elt = mkTyConApp mVarPrimTyCon [s, elt]
\end{code}
%************************************************************************
%* *
%************************************************************************
-Foreign objects (formerly ``Malloc'' pointers) provide a mechanism which
-will let Haskell's garbage collector communicate with a {\em simple\/}
-garbage collector in the IO world. We want Haskell to be able to hold
-onto references to objects in the IO world and for Haskell's garbage
-collector to tell the IO world when these references become garbage.
-We are not aiming to provide a mechanism that could
-talk to a sophisticated garbage collector such as that provided by a
-LISP system (with a correspondingly complex interface); in particular,
-we shall ignore the danger of circular structures spread across the
-two systems.
+A Foreign Object is just a boxed, unlifted, Addr#. They're needed
+because finalisers (weak pointers) can't watch Addr#s, they can only
+watch heap-resident objects.
-There are no primitive operations on @ForeignObj#@s (although equality
-could possibly be added?)
+We can't use a lifted Addr# (such as Addr) because race conditions
+could bite us. For example, if the program deconstructed the Addr
+before passing its contents to a ccall, and a weak pointer was
+watching the Addr, the weak pointer might deduce that the Addr was
+dead before it really was.
\begin{code}
foreignObjPrimTy = mkTyConTy foreignObjPrimTyCon
foreignObjPrimTyCon = pcPrimTyCon foreignObjPrimTyConKey SLIT("ForeignObj#") 0 ForeignObjRep
\end{code}
+
+%************************************************************************
+%* *
+\subsection[TysPrim-Weak]{The ``weak pointer'' type}
+%* *
+%************************************************************************
+
+\begin{code}
+weakPrimTyCon = pcPrimTyCon weakPrimTyConKey SLIT("Weak#") 1 WeakPtrRep
+
+mkWeakPrimTy v = mkTyConApp weakPrimTyCon [v]
+\end{code}
+
+%************************************************************************
+%* *
+\subsection[TysPrim-thread-ids]{The ``thread id'' type}
+%* *
+%************************************************************************
+
+A thread id is represented by a pointer to the TSO itself, to ensure
+that they are always unique and we can always find the TSO for a given
+thread id. However, this has the unfortunate consequence that a
+ThreadId# for a given thread is treated as a root by the garbage
+collector and can keep TSOs around for too long.
+
+Hence the programmer API for thread manipulation uses a weak pointer
+to the thread id internally.
+
+\begin{code}
+threadIdPrimTy = mkTyConTy threadIdPrimTyCon
+threadIdPrimTyCon = pcPrimTyCon threadIdPrimTyConKey SLIT("ThreadId#") 0 ThreadIdRep
+\end{code}
+
+%************************************************************************
+%* *
+\subsection[TysPrim-PrimRep]{Making types from PrimReps}
+%* *
+%************************************************************************
+
+Each of the primitive types from this module is equivalent to a
+PrimRep (see PrimRep.lhs). The following function returns the
+primitive TyCon for a given PrimRep.
+
+\begin{code}
+primRepTyCon CharRep = charPrimTyCon
+primRepTyCon IntRep = intPrimTyCon
+primRepTyCon WordRep = wordPrimTyCon
+primRepTyCon Int64Rep = int64PrimTyCon
+primRepTyCon Word64Rep = word64PrimTyCon
+primRepTyCon AddrRep = addrPrimTyCon
+primRepTyCon FloatRep = floatPrimTyCon
+primRepTyCon DoubleRep = doublePrimTyCon
+primRepTyCon StablePtrRep = stablePtrPrimTyCon
+primRepTyCon ForeignObjRep = foreignObjPrimTyCon
+primRepTyCon WeakPtrRep = weakPrimTyCon
+primRepTyCon other = pprPanic "primRepTyCon" (ppr other)
+\end{code}
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