[Haskell-cafe] weird behavior with FFI

[Tim Newsham]

I am working on haskell bindings to C functions using FFI.  I have
a callback function that returns "IO ()".  When I pass in the callback
function:
     foo = printf "foo"

it crashes (is there an easy way to debug this exception using ghc6.8.2?)
     bot: SilcClient_d1al: uncaught exception

however, if I pass in the callback function:
     foo = do
         printf "foo"
         return ()

it does not crash.  Is this a bug in my bindings?  In ghc/ffi?
Full code is at:
    http://www.thenewsh.com/%7Enewsham/silcbot.tgz

Tim Newsham
http://www.thenewsh.com/~newsham/