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<p>Yes you can call Haskell code from C:
<a class="moz-txt-link-freetext" href="https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/ffi-ghc.html#foreign-export-ghc">https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/ffi-ghc.html#foreign-export-ghc</a><br>
</p>
If you really want to use Haskell, I would go full Haskell to avoid
complications (you can update the FUSE bindings if necessary). On
the other hand, if you plan to distribute your FS implementation to
a non-Haskell audience, maybe it would be better to write it fully
in C.<br>
<br>
<br>
<div class="moz-cite-prefix">On 10/05/2016 20:56, Silent Leaf wrote:<br>
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cite="mid:CAGFccjPhfVOGq_G6EL2D_XBgSPdocKHJxhuJdmVN8+1vsgEgGA@mail.gmail.com"
type="cite">
<div dir="ltr">Thanks! FUSE seems a perfect way to do what I wanna
do.<br>
<br>
Hypothetically, what if I wanted to bypass the Haskell bindings,
directly use FUSE in C, but write most of the actual operations
in Haskell? <br>
AKA, is it possible to call haskell functions/programs *from* C
code? And have all individual calls to the Haskell parts be
allowed to share private data, rather than being independent,
isolated calls?<br>
<br>
It's just an idea, I figured since writing a fuse filesystem in
C doesn't seem too complicated (i found a tutorial, and it just
looks like what the Haskell bindings is proposing, except well
in theory one has to write everything in C) and i figured
perhaps it'd be better/faster, possibly less buggy (the Haskell
bindings are tagged experimental, of which i couldn't tell the
true interpretation, but which doesn't seem terribly appealing
at first sight) to write the FUSE in C, *except* for, well most
of the actual "doing something" code, aka the FS operations,
which would be written in Haskell.<br>
<br>
AKA, the final program would start with C, but under the hood
use Haskell for most of the meaningful code. This, of course, if
such a thing is even possible in the first place! And easily,
needless to say. Considering for that matter as I said that the
Haskell parts should be able to save private data of its own
without having to "start over" the "situation analysis" for each
individual call to one of the filesystem operations.<br>
<br>
Thanks a lot again!<br>
<br>
Le lundi 9 mai 2016, Sylvain Henry <<a moz-do-not-send="true"
href="mailto:sylvain@haskus.fr" target="_blank">sylvain@haskus.fr</a>>
a écrit :<br>
> Hi,<br>
><br>
> You don't have to write a kernel module (which would better
be written in C), you can do everything in userspace and in
Haskell with FUSE: <a moz-do-not-send="true"
href="https://en.wikipedia.org/wiki/Filesystem_in_Userspace"
target="_blank">https://en.wikipedia.org/wiki/Filesystem_in_Userspace</a><br>
> It seems to already have Haskell bindings: <a
moz-do-not-send="true"
href="https://hackage.haskell.org/package/HFuse-0.2.4.5/docs/System-Fuse.html"
target="_blank"><a class="moz-txt-link-freetext" href="https://hackage.haskell.org/package/HFuse-0.2.4.5/docs/System-Fuse.html">https://hackage.haskell.org/package/HFuse-0.2.4.5/docs/System-Fuse.html</a></a><br>
><br>
> To implement the file system operations, you can use binary
(<a moz-do-not-send="true"
href="https://hackage.haskell.org/package/binary"
target="_blank">https://hackage.haskell.org/package/binary</a>),
Foreign.Ptr, Data.Bits, etc. You can write data on any real
partition by using the associated block devices (e.g.,
/dev/sda1).<br>
><br>
> Sylvain<br>
><br>
> On 09/05/2016 20:50, Silent Leaf wrote:<br>
><br>
> Mostly all in the title.<br>
><br>
> I have a project of developing a personal filesystem,
possibly at first virtual (the file(s) representing a virtual
partition formatted with my filesystem, would be saved in a host
filesys, eg ext4 or whatever), but probably in the end not
virtual, directly working on the contents of a real partition.<br>
><br>
> Can haskell do that kind of thing, aka writing data on a
partition directly (without using a known filesys), etc? Is it
at least more or less adapted for this task (not talking about
performances, unless the consequences be a *really* slow
filesys), aka doable, easily doable, relatively speaking (aka
not worse than with another language)?<br>
> Incidentally, if i wanted Linux to recognize the filesys,
i've heard one has to write a module and put it in connection
with the kernel or something. could haskell do that?<br>
><br>
> if that's a "no" somewhere for one of my questions, which
parts can't be written in haskell (without horrible performances
or code very very hard to write), and can they be written in C
(or whatever) as foreign functions? which parts would that
represent for the whole program?<br>
><br>
> Thanks a lot in advance!<br>
><br>
> PS: just in case, tips on sources of information on how to
do any of the above will be extremely appreciated! (even if it's
in, say C, for that matter, providing there's a way to translate
the steps into a haskell program)<br>
><br>
> _______________________________________________<br>
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href="http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners"
target="_blank">http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners</a><br>
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>
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