Re: Accessing ForeignObj contents from Haskell

[Manuel M. T. Chakravarty]

[EMAIL PROTECTED] (Marcin 'Qrczak' Kowalczyk) wrote,

> Wed, 16 Aug 2000 08:06:59 -0700, Simon Marlow <[EMAIL PROTECTED]> pisze:
> 
> > This is a problem we've known about for a while, and it's one reason
> > we have ForeignObj: because they're atomic heap objects and therefore
> > don't suffer from transformational bogosity.
> 
> Oops. I think I understand now how ForeignObjs work.
> 
> So they have to stay. ForeignObj users can use the generic wrapper
>     foreignObjToPtr :: (Ptr a -> IO b) -> ForeignObj -> IO b
> instead of dedicated peek functions.

>From a users point of view, I like these functions that
basically delimit a block by having the stuff in the block
as a higher-order function, but I have two concerns:

* Shouldn't we use

    foreignObjToPtr :: ForeignObj -> (Ptr a -> IO b) -> IO b

  as it allows to write

    foreignObjToPtr fptr $ \ptr -> do
      ...
      ...

* Does GHC usually do inlining here?  In the marshalling
  code for a single function, there can be quite lot of
  these scopes being nested.  Will this have implications on
  program performance?

  Simon, what do you reckon?  Is it inlined usually?

Cheers,
Manuel