[Haskell-cafe] Anonymous FFI calls

[adam vogt]

On Wed, Feb 11, 2015 at 12:26 PM, Sylvain Henry <hsyl20 at gmail.com> wrote:
> 2015-02-11 16:18 GMT+01:00 Francesco Mazzoli <f at mazzo.li>:
>>
>>
>> Relatedly, if I have some function pointer known at runtime that
>> addresses a C function that takes some arguments, I have no way to
>> invoke it from Haskell, since all FFI imports must be declared at
>> compile-time, and I don't know the address of the symbol I want to
>> execute at compile time.
>
>
> You can use FunPtr and wrapper imports to convert a FunPtr into a Haskell
> function.
> https://hackage.haskell.org/package/base-4.7.0.2/docs/Foreign-Ptr.html#g:2
>
> You may be interested in my dynamic-linker-template package [1] to avoid
> having to write boilerplate wrappers.

Code using http://hackage.haskell.org/package/libffi looks pretty
similar, though the specification needs terms (such as argCInt)
instead of a mandatory type signature. GHC itself includes libffi so
maybe the foreign import "dynamic" calls end up doing exactly the same
thing as the hackage libffi does.