base package (Was: GHC 7.8 release?)

Simon Peyton-Jones simonpj at
Fri Feb 15 10:36:10 CET 2013

| > 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.


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