[Haskell-cafe] How can I pass IOUArrays to FFI functions?

Ryan Ingram ryani.spam at gmail.com
Tue Aug 21 02:47:06 EDT 2007

> Your code is broken in a most evil and insidious way.

Interesting.  This is for a toy project, so I'm not too worried, but lets
say I wanted to do this "correctly" and I was set on using IOUArray for some
reason. (The Haskell wiki claims that StorableArray is slower; is that
actually the case?)

Which of the following fixes would work now?  Which has the lowest
probability of not working in the future?

1) Declare f to take Addr# and don't construct a Ptr Word32
    I suspect this would be enough unless the GC changed to some sort of
continous GC which can happen even without an allocation

2) Declare f to take MutableByteArray#
    Is this good enough to make the collector happy?

3) Something else I haven't thought of?

If there was no other option, and StorableArray wasn't slower, and I was
working on a real project, I'd probably wrap my own around ForeignPtr like

  -- ryan
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