Re: [Ocaml-lib-devel] Future of ExtLib

[Nicolas C. <war...@fr...>]

> > - base64 encode/decode
> > - abstract high level I/O with support for C basic types ( read_i16 ,
> > write_f16 ..... )
> > - zlib deflate/inflate written in pure OCaml.
>
> One of the things I've been nooddling around with is a radicaly new I/O
> arhitecture.  The basic idea is to make i/o more like java and less like
> C.  The core idea is that there would be four classes of objects:
[...]

Hi Brian,
What we need is an high-level IO abstraction that will offer a wide API for
most of the common usages.
The IO module I posted earlier on this list was a beginning of answer to
this. It didn't made his way to the CVS because I lacked time, but looks
like there was no people against it.
In this IO module, I made the following choices regarding polymorphism :

(quoting myself)

For efficiency reason each input/output have two ways of reading/writing
data : for example a channel input can write char by char or directly
strings. it's then a (char,string) input. An ouput takes a third parameter
which is the value returned by a call to close.


(end-of-quote)

So we have here :
    * ('a,'b) input  : an input to a file is a (char,string) input
    * ('a,'b,'c) output : an output to a buffer is a (char,string,string)
output since "closing" the buffer returns the total string written into
we can provide several conversion "parsers" functions such as
    * val in_ord : (char,string) input -> (int,int list) input
    * val in_chr : (int,int list) input -> (char,string) input
or "filters" such as :
    * val in_b64 : (char,string) input -> (char,string) input
    * val out_zlib : (char,string,'a) output -> (char,string,'a) output

Concerning the "Directories", I think its even more high level and should be
handled in a different module that will be built on top of IO. Please
remember that the "file" concept have no meaning in an abstract IO.
Concerning Unicode, adding a filter to handle this looks okay (not by
default). For the "polymorphism" of formatters, this is not really possible
in the OCaml type system. One choice is to use printf/scanf on an output :
that's exactly what's I'm doing in IO module.

Regards,
Nicolas Cannasse