Re: FPS, ForeignPtr and GHC 6.6

Bulat Ziganshin wrote:
> Hello Simon,
>
> Friday, April 21, 2006, 3:44:17 PM, you wrote:
>
>
> > The point is that you can't implement all the operations in FPS using a
> > ByteArray# representation, so that's a bogus comparison.
>
> that operations can't be implemented with pinned byte arrays? i think
> only mmap support?

Many of the operations in "Low-level constructors"

  http://www.cse.unsw.edu.au/~dons/fps/Data.FastPackedString.html#21

plus mmapFile.

> > ForeignPtr is the right thing!
>
> they are slower in 6.4

Performance with 6.4 isn't a priority, since the library is going into 
6.6.  By all means write a version that works better with 6.4 in the 
meantime.

> data ForeignPtrContents
>   = PlainForeignPtr !(IORef [IO ()])
>   | MallocPtr (MutableByteArray# RealWorld) !(IORef [IO ()])
>
> you mean adding 3rd variant here:
>
>   | PlainMallocPtr (MutableByteArray# RealWorld)
>
> ?

Yes

> btw, i still wondering - that is the difference between
> MutableByteArray# and ByteArray# ? :)

ByteArray# doesn't have the state parameter, it can be read outside of 
the IO/ST monads.  The point is to add a little type safety, it doesn't 
have any impact on the implementation.

Cheers,
        Simon