Hi Bas,

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?).

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

> 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)
??

GHC accepts it.
And then every function for lazy vectors can then be written like:

import qualified Data.Vector.Generic as G (Vector(..))

cons :: (G.Vector v) => a -> Vector v a -> Vector v a
cons x v = ...

and also (even better):

instance (G.Vector v) => G.Vector (Vector v) where
    cons x v = ...

Just make aliases to follow the API, for instance in Data.Vector.Lazy:

import qualified Data.Vector.Lazy.Internal as L
import qualified Data.Vector as V

type Vector a = L.Vector V.Vector a

Le 27 mars 2012 20:38, Bas van Dijk <v.dijk.bas@gmail.com> a écrit :
On 27 March 2012 11:00, Yves Parès <yves.pares@gmail.com> wrote:
> Hello,
>
> As vector provides a class generalizing all flavours
> (Data.Vector.Generic.Vector), it occurs to me that the same could be done
> for ByteString. Then, packages based on it would have the choice between
> hardcoded and generic, they wouldn't have to duplicate a module to handle
> both strict and lazy versions, as (with the exception of functions for
> communication with C code) they already provide the same API.
> I would be willing to make it, it's a concern I've had in mind for a long
> time, but as I'm pretty sure the idea isn't new, I would very much like to
> know if and what arguments (related to performance maybe ? I don't know...)
> were raised against that.

It's not entirely what you need but are you aware of my
vector-bytestring library?

http://hackage.haskell.org/package/vector-bytestring

It doesn't (yet) abstract over strict and lazy ByteStrings. But that
would be a nice addition!

In an ideal world we would have a Lazy type family which for each type
of vector would return its lazy version (where the vector is unpacked
in the cons cell). Then we would need your generic API for working
with both lazy and strict vectors.

Regards,

Bas