base package (Was: GHC 7.8 release?)

Simon Marlow marlowsd at
Fri Feb 15 15:37:23 CET 2013

On 15/02/13 09:36, Simon Peyton-Jones wrote:
> | > Doesn't the FFI pull in some part of the I/O layer, though?  In
> | > particular threaded programs are going to end up using forkOS?
> |
> | Another good reason to try to have a pure ground library.
> Remember that we have UNSAFE ffi calls and SAFE ones.
> The SAFE ones may block, cause GC etc.  They involve a lot of jiggery pokery and I would not be surprised if that affected the I/O manager.
> But UNSAFE ones are, by design, no more than "fat machine instructions" that are implemented by taking an out-of-line call.  They should not block.  They should not cause GC.  Nothing.  Think of 'sin' and 'cos' for example.
> Fingerprinting is a classic example, I would have thought.
> So my guess is that it should not be hard to allow UNSAFE ffi calls in the core (non-IO-ish) bits, leaving SAFE calls for higher up the stack.

Actually as far as the Haskell-level API goes, there's no difference 
between safe and unsafe FFI calls, the difference is all in the codegen. 
  I don't think safe calls cause any more difficulties for splitting up 
the base.


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