[Haskell-iPhone] FFI for living in C

[Luke Iannini]

Hi guys,

It's also possible to start the Haskell runtime from within C/C++,
using the hs_init() and hs_exit() functions (you can just call them
each one at startup and shutdown before calling into any Haskell code
that's been "foreign export"ed), to skip the c_main business.

See 8.2.1.1 here:
http://www.haskell.org/ghc/docs/7.4.1/html/users_guide/ffi-ghc.html

There's a great chapter in Real World Haskell on exporting and
importing functions to call to and from C/C++:
http://book.realworldhaskell.org/read/interfacing-with-c-the-ffi.html

For Objective-C, Objective Haskell is an even higher level (and quite
excellent) project for calling to and from Obj-C and converting its
standard data types (NSDictionaries, NSStrings, NSData etc.) into
Haskell's (Maps, Text, ByteStrings etc.), and vice-versa.
https://github.com/jspahrsummers/ObjectiveHaskell

It uses Template Haskell to make importing and exporting extremely
easy and clean, but sadly ghc-ios doesn't support TH quite yet. I have
an experimental branch that replaces the TH with manually-written
boilerplate but of course it's a lot messier. I'll be publishing it
soon anyway : ).

Cheers
Luke

On Sat, Dec 1, 2012 at 1:26 PM, Stephen Paul Weber
<singpolyma at singpolyma.net> wrote:
> Somebody claiming to be Casey Basichis wrote:
>>
>> Is the FFI the right tool for a situation where, while used extensively,
>> Haskell is more or less there to take in data, like lists and spit out
>> data
>> like vectors etc back to C.
>
>
> My current favourite way to do this is to start in Haskell-land and call
> some entry-point function in extern "C" that takes function pointers as
> arguments.  These function pointers become the way that C++ code can call
> back into Haskell-land.
>
> This is what I am using for <http://github.com/singpolyma/haskades>
>
> --
> Stephen Paul Weber, @singpolyma
> See <http://singpolyma.net> for how I prefer to be contacted
> edition right joseph
>
>
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