Re: [Caml-list] Immutable strings

[Gerd Stolpmann <info@gerd-stolpmann.de>]

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Am Freitag, den 04.07.2014, 14:31 -0600 schrieb Anthony Tavener:
> It seems the "bytes" type would be most useful in cases where mutable
> and
> immutable strings are used in a mixed manner... but given these
> practical
> issues you raise, it could be less pleasant than it first appears.
> Your
> "stringlike" solution seems reasonable, but I don't have a good
> use-case in
> mind for mixed mutable/immutable to help me imagine the result. What
> are some
> scenarios where this mix of types is desired? I think even Rust
> doesn't
> support mutable strings -- which seems bold for its target audience,
> yet
> they're fine with it?

I've mostly buffers in mind, as you need them for block-by-block I/O.
Actually, I started thinking about this issue when looking again at
OCamlnet, and how I could use "bytes" there. It's a hard case, lots of
buffers of different types, and you really run into the problems I
sketched in the article, as it is a common operation to copy the
contents of one buffer into the other.

That's also why I'm suggesting to use bigarrays - for interfacing with C
these are much easier to use as buffers, as bigarrays are just malloc'ed
memory and cannot be moved around by the GC. (And the C interface is
needed for I/O.)

So my scenario is quite low-level: I/O, and C interfaces.

> When I consider possible scenarios of utf8 encoded strings,

No, that's a no-go, of course. When it comes to real text, mutability
doesn't give you much.

Gerd


>  and mutating that
> in-place... ugh. Even "back in the day", doing string operations in C
> on
> ASCII, I'd favor building a new string rather than flirting with
> saving ops by
> overwriting values in the current string. Oh! Upper/lower-case! Maybe
> that's
> the one good use-case. ;)
> 
> 
> 
> 
> On Fri, Jul 4, 2014 at 1:18 PM, Gerd Stolpmann
> <info@gerd-stolpmann.de> wrote:
>         Hi list,
>         
>         I've just posted a blog article where I criticize the new
>         concept of
>         immutable strings that will be available in OCaml 4.02 (as
>         option):
>         
>         http://blog.camlcity.org/blog/bytes1.html
>         
>         In short my point is that it the new concept is not far
>         reaching enough,
>         and will even have negative impact on the code quality when it
>         is not
>         improved. I also present three ideas how to improve it.
>         
>         Gerd
>         --
>         ------------------------------------------------------------
>         Gerd Stolpmann, Darmstadt, Germany    gerd@gerd-stolpmann.de
>         My OCaml site:          http://www.camlcity.org
>         Contact details:        http://www.camlcity.org/contact.html
>         Company homepage:       http://www.gerd-stolpmann.de
>         ------------------------------------------------------------
>         
>         
>         
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> 

-- 
------------------------------------------------------------
Gerd Stolpmann, Darmstadt, Germany    gerd@gerd-stolpmann.de
My OCaml site:          http://www.camlcity.org
Contact details:        http://www.camlcity.org/contact.html
Company homepage:       http://www.gerd-stolpmann.de
------------------------------------------------------------


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