Re: Improved interface to UArray

I meant specifically using PrimMonad, rather than the prim array facilities, to write the instances On Tue, Mar 3, 2020 at 5:14 PM Zemyla wrote:

Because a lot of the stuff is defined in GHC.Arr, in base. Also, the Prim instance for Bool is different than the UArray instance for Bool.

On Tue, Mar 3, 2020, 14:56 chessai . wrote:

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Zemlya, could you expound on why you think a primitive dependency is a bad idea? I'm just not sure what reasons you have in mind.

Thanks

On Tue, Mar 3, 2020, 12:31 PM Zemyla wrote:

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We should probably use something similar, but I don't think a dependency on primitive is a good idea.

On Tue, Mar 3, 2020, 14:28 Carter Schonwald wrote:

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Hey Zemyla! one fuzzy question i have, and perhaps you have a perspective on this, would/could the PrimMonad machinery in primitive help simplify / clean up stuff here too?

On Mon, Feb 24, 2020 at 9:46 AM Zemyla wrote:

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It's currently hard to describe that a type should be usable with UArray or IOUArray, and almost impossible to describe without QualifiedConstraints that it should be usable with STUArray. And it's actually impossible to use GeneralizedNewtypeDeriving to derive new instances of IArray or MArray. It also means that it's difficult to keep the three sets of instances in sync.

Therefore, there should be (taking inspiration from primitive) a class that describes types which can be used in unboxed arrays. It'd be something along the lines of:

class Unboxed e where unsafeNewUArray :: Int# -> e -> State# s -> (# State# s, MutableByteArray# s #) unsafeNewUArray_ :: Const (Int# -> State# s -> (# State# s, MutableByteArray# s #)) e unsafeReadUArray :: MutableByteArray# s -> Int# -> State# s -> (# State# s, e #) unsafeWriteUArray :: MutableByteArray# s -> Int# -> e -> State# s -> State# s unsafeIndexUArray :: ByteArray# -> Int# -> e

And then the instances for UArray, STUArray, and IOUArray would be:

instance Unboxed e => IArray UArray e where ... instance Unboxed e => MArray IOUArray e IO where ... instance Unboxed e => MArray (STUArray s) e (ST s) where ...

Incidentally, this also means it'd be less effort to add instances like Unboxed CInt, Unboxed a => Unboxed (Complex a), and Unboxed Ordering. _______________________________________________ Libraries mailing list Libraries@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/libraries

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