Re: [Haskell-cafe] [ANNOUNCE] Bindings for libguestfs
On Wed, May 13, 2009 at 11:15:24PM +1000, Peter Gammie wrote: Hope this helps! Thanks for your honest helpful answer. I think I will try again at compiling c2hs so I can look at the code that it generates. Rich. -- Richard Jones, Emerging Technologies, Red Hat http://et.redhat.com/~rjones virt-df lists disk usage of guests without needing to install any software inside the virtual machine. Supports Linux and Windows. http://et.redhat.com/~rjones/virt-df/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] [ANNOUNCE] Bindings for libguestfs
On Tue, May 12, 2009 at 03:11:32PM -0400, John Dorsey wrote: Richard, I added some partial bindings for libguestfs[1] here: http://git.et.redhat.com/?p=libguestfs.git;a=blob;f=haskell/Guestfs.hs;hb=HEAD Terrific! Partial bindings are great. Thanks for releasing it. I haven't taken the time to look at your code, but... BTW, I found the documentation on writing FFIs very contradictory and incomplete. For example, I was completely defeated trying to find ways to do simple stuff like passing in integers or returning booleans. *Potentially* Haskell's FFI seems like it might be one of the best out of the languages I've used so far, but it needs way more documentation and examples. Can you be more specific about what needs improvement? I wrote a partial Haskell binding for Net-SNMP recently, and I got along pretty well using the API docs at http://www.haskell.org/ghc/docs/latest/html/libraries/index.html, and an example in RWH using hsc2hs. I guess it's easier if one is more used to Haskell (see my .sig) What did you see that was contradictory? Specific things would be: Recommendation to use 'throwDyn' to throw exceptions, yet this function doesn't exist in my version of GHC. In fact, none of the code here: http://www.haskell.org/haskellwiki/FFICookBook#Raising_and_handling_exceptions works in GHC at all, as far as I could tell. No good examples available on how to use ForeignPtr. Yet I'd argue that almost any non-trivial modern C library bindings will have some concept of an opaque object, so this is the most vital example. (The examples in RWH ch 17 weren't enough for me). I'd really like to know what parameters and return types are permissible for 'foreign import ccall' statements. By trial and error I found out. How do I convert to/from booleans? How do I really use C structures? Real examples, please. How can I free a C string that is returned from a 'caller frees' C function? Does Foreign.Marshall.Alloc.free work for this? Again, reflecting my own inexperience with Haskell, I found 'withCString', 'maybeWith', 'withMany', 'withArray0' etc to be both undocumented and extremely confusing to use. How do I specify a 64 bit int? Using 'Int64#' just causes syntax errors. What's a good emacs editing mode for Haskell code? My emacs thinks Haskell code is LISP ... Rich. -- Richard Jones, Emerging Technologies, Red Hat http://et.redhat.com/~rjones Read my programming blog: http://rwmj.wordpress.com Fedora now supports 75 OCaml packages (the OPEN alternative to F#) http://cocan.org/getting_started_with_ocaml_on_red_hat_and_fedora ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] [ANNOUNCE] Bindings for libguestfs
I added some partial bindings for libguestfs[1] here: http://git.et.redhat.com/?p=libguestfs.git;a=blob;f=haskell/Guestfs.hs;hb=HEAD Some very simple example programs which use these bindings: http://git.et.redhat.com/?p=libguestfs.git;a=tree;f=haskell;hb=HEAD Any comments welcome. My Haskell skills are pretty terrible, so I'm sure there are many ways these can be improved. If someone wants to look at binding the rest of the API, then please send me some patches. (Note that the Guestfs.hs file is automatically generated). BTW, I found the documentation on writing FFIs very contradictory and incomplete. For example, I was completely defeated trying to find ways to do simple stuff like passing in integers or returning booleans. *Potentially* Haskell's FFI seems like it might be one of the best out of the languages I've used so far, but it needs way more documentation and examples. Rich. [1] http://et.redhat.com/~rjones/libguestfs/ -- Richard Jones, Emerging Technologies, Red Hat http://et.redhat.com/~rjones virt-df lists disk usage of guests without needing to install any software inside the virtual machine. Supports Linux and Windows. http://et.redhat.com/~rjones/virt-df/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] [ANNOUNCE] Bindings for libguestfs
On Tue, May 12, 2009 at 08:18:08AM -0700, Don Stewart wrote: rjones: I added some partial bindings for libguestfs[1] here: http://git.et.redhat.com/?p=libguestfs.git;a=blob;f=haskell/Guestfs.hs;hb=HEAD Some very simple example programs which use these bindings: http://git.et.redhat.com/?p=libguestfs.git;a=tree;f=haskell;hb=HEAD Any comments welcome. My Haskell skills are pretty terrible, so I'm sure there are many ways these can be improved. If someone wants to look at binding the rest of the API, then please send me some patches. (Note that the Guestfs.hs file is automatically generated). Very cool. Are you likely to upload to hackage? I think it should be a bit more complete before uploading it. It only covers about half the interface. BTW, I found the documentation on writing FFIs very contradictory and incomplete. For example, I was completely defeated trying to find ways to do simple stuff like passing in integers or returning booleans. *Potentially* Haskell's FFI seems like it might be one of the best out of the languages I've used so far, but it needs way more documentation and examples. Perhaps read the FFI chapter of RWH (online?) What resources were you using to grok the FFI? Well, Real World Haskell was one of the resources: http://book.realworldhaskell.org/read/interfacing-with-c-the-ffi.html (And it's fine, one of the better resources as an introduction. But not thorough enough to cover the booleans / returning complex structs problems I had). The others, as I remember it, were: http://www.haskell.org/haskellwiki/FFI_Introduction http://www.haskell.org/haskellwiki/FFICookBook (Made me think it was simple, but doesn't really cover much once I got down to the details) http://www.cse.unsw.edu.au/~chak/haskell/ffi/ the documentation for 'Foreign' etc in the Haddock-generated library docs. Rich. -- Richard Jones, Emerging Technologies, Red Hat http://et.redhat.com/~rjones virt-df lists disk usage of guests without needing to install any software inside the virtual machine. Supports Linux and Windows. http://et.redhat.com/~rjones/virt-df/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
