Hello oleg, Wednesday, February 08, 2006, 8:37:55 AM, you wrote:
I suggest you follow the same scheme as the unboxed array types, and have IOURef/STURef types, parameterised over the element type. Of course, we should have instances for all of the primitive numeric types plus Ptr, ForeignPtr, StablePtr, Bool.
opc> Perhaps it may be worth to introduce a class Unpackable as described opc> at the end of opc> http://www.haskell.org/pipermail/haskell-cafe/2004-July/006400.html opc> so we may define STUArray as an instance of MArray, and other similar opc> unpackable things easier? i just implemented this neat idea. this allowed to define all sorts of unboxed arrays and references in just 300 lines of code! for those who are not seen the discussion, it's a brief presentation of implemented facilities: 1. Types IOURef/STURef represent fast alternative to the IORef/STRef types. These "unboxed references" may be used only for simple datatypes, including Bool, Char, Int..Int64, Word..Word64, Float, Double, Ptr, FunPtr, StablePtr, but for these types they are guarantee maximum speed! The unboxed references completely replaces the "Fast Mutable Ints/Words/Bools" modules used before. To use unboxed references instead of boxed ones, you just need to replace IORef/STRef in type declarations to the IOURef/STURef and add the same "U" letter to the names of operations that use these references: main = do (i :: IORef Int) <- newIORef 1 readIORef i >>= print writeIORef i 2 will become: main = do (i :: IOURef Int) <- newIOURef 1 readIOURef i >>= print writeIOURef i 2 The library includes compatibility code that allows to use IOURef/STURef on other Haskell compilers. That allows to debug code that use the unboxed references with Hugs/NHC, and use for the final optimized compilation GHC/JHC. 2. Classes MRef and Var can be used to write monad-independent code that use mutable variables. Class MRef represents monad-independent boxed references, while class Var represents the unboxed ones. You can find examples of their usage in the Streams library. These classes uses functional dependencies, so they are available only in GHC/Hugs. 3. Module GHC.Unboxed also contains implementation of UnboxedArray, UnboxedSTArray and UnboxedIOArray type constructors, what is a full analogues of UArray, STUArray and IOUArray, only much easier to implement. These definitions follow the scheme proposed by Oleg: "instance (Unboxed e) => IArray UnboxedArray e" and so on. 4. You can define new unboxed types. For example, the code that defines "instance Unboxed Bool" can be reused without any modifications for any user-defined enumeration. -- Best regards, Bulat mailto:bulatz@HotPOP.com