On Tue, Feb 07, 2012 at 06:26:48PM -0800, John Meacham wrote:
Hi, from my reading, it looks like 'capi' means from a logical perspective,
"Don't assume the object is addressible, but rather that the standard c syntax for calling this routine will expand into correct code when compiled with the stated headers"
So, it may be implemented by say creating a stub .c file that includes the headers and creates a wrapper around each one or when compiling via C, actually including the given headers and the function calls in the code.
That sounds right. It basically means you don't have to write the C stubs yourself, which is nice because (a) doing so is a pain, and (b) when the foreign import is inside 2 or 3 CPP conditionals it's even more of a pain to replicate them correctly in the C stub. Unfortunately, there are cases where C doesn't get all the type information it needs, e.g.: http://hackage.haskell.org/trac/ghc/ticket/2979#comment:14 but I'm not sure what the best fix is.
I ask because jhc needs such a feature (very hacky method used now, the rts knows some problematic functions and includes hacky wrappers and #defines.) and I'll make it behave just like the ghc one when possible.
Great! Thanks Ian