Re: [Caml-list] OCaml on iPhone (was: arm backend)

[Robert Muller <muller@cs.bc.edu>]

This sounds great.  I will be teaching an iphone programming course  
next year and I would
very much like to use the course as an opportunity to introduce  
students to caml. I know that
there are others gearing up for iphone programming courses who aren't  
thrilled with the idea
of teaching Objective C.

If you were to post your resources on a web site it might lower the  
barrier to entry for more
people to use ocaml + your wrappers rather than Objective C.

Bob Muller


On May 2, 2009, at 7:15 PM, Jeffrey Scofield wrote:

> Nathaniel Gray <n8gray@gmail.com> writes:
>
>> Ok, I'm glad I left this to people who are familiar with ARM
>> assembly programming.  :-)
>
> We've done a lot of assembly programming, but none of us is an
> ARM expert.  We looked at ARM documents and the assembly (.s)
> files generated by ocamlopt and gcc, and spent some long sessions
> with gdb.
>
>> Awesome, but now I'm confused because the arm.S you included
>> has lots of .global pseudo-ops.  Do you not compile it with
>> Apple's as?
>
> At around line 36, you'll see:
>
>  #define global globl
>
> As I said in private mail, you could call this a hack, but it's a
> way to avoid making lots of small changes everywhere in the file.
>
>> What's your app?
>
> We're working on a collection of card games for casual play.
>
>> How are you managing the interface between Cocoa and OCaml?
>
> This is a big topic.  The summary is that we model Cocoa objects
> as OCaml objects.  We have a layer that wraps OCaml objects in
> smallish ObjC objects for use on the ObjC side, and wraps ObjC
> objects in smallish OCaml objects for use on the OCaml side.  The
> layer then translates between these representations as required
> for calls into iPhoneOS and Cocoa Touch from OCaml (asking for
> iPhone OS services) and into OCaml from iPhoneOS (for event
> handling).
>
>>> We also made a small fix to the ARM code generator
>>
>> I am very interested in any and all information needed to get a
>> correct OCaml port suitable for use in App Store applications.
>> Please share!
>
> OK, I'll gather up our patch and send it to the list.  I want to
> separate out our changes from those of Toshiyuki Maeda [1].
>
> As I said, our patch fixes calls to external C float functions
> such as floor(), sin(), and so on.  There is special handling in
> ocamlopt to allow them to be unboxed, but the ABI of the existing
> ARM code generator doesn't match the iPhone ABI.
>
> Regards,
>
> Jeff Scofield
> Seattle
>
> [1] http://web.yl.is.s.u-tokyo.ac.jp/~tosh/ocaml-on-iphone/
>
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