[Haskell-cafe] Arguments against an hypothetical Data.ByteString.Generic?

[Bas van Dijk]

On 27 March 2012 21:46, Yves Parès <yves.pares at gmail.com> wrote:
> Yes, thank you to remind me of that, I remember now having seen the project.
> Strict ByteStrings being an alias to Vector Word8 is a good idea (are
> bytestrings are already implemented exactly like
> Data.Vector.Storable.Vector). But in that case we could use the API of
> vector for bytestrings (the bytestring API would be provided only for
> backwards compatibility, right?).

Yes, I hope that one day the bytestring package and the ByteString
type will be deprecated in favor of vector and
Data.Vector.Storable.Vector Word8 respectively. vector-bytestring is
indeed intended as a package which should make the transition easier.

> Does vector-bytestring plans to be the new implementation for bytestrings in
> the end or is it a side-package?

I hope that once we get on par with bytestring's performance we can
replace it (we're almost there!, Yell if you want to see some
benchmark results).

>> In an ideal world we would have a Lazy type family which for each type
>> of vector would return its lazy version
>
> What about a type like:
>
> data Vector v a = Empty | Chuck {-# UNPACK #-} !(v a) (Vector v a)
> ??

If you build with -Wall you'll see the following unfortunate warning:

Warning: Ignoring unusable UNPACK pragma on the
             first argument of `Chunk'

Johan Tibell recently discussed some of his ideas on how to solve this:

http://www.haskell.org/pipermail/glasgow-haskell-users/2012-March/022079.html

But for now we need to make a specialized type for every different
vector type and use an associated type family to abstract over these
different types.

Regards,

Bas