dynamic loading with ghc api?

[Rob Nikander]

Is the 'plugins' package compatible with dynamic linking of the main
program?   I ask because I wrote a test program using
System.Plugins.load and it works fine, but when I link it to the GHC
api using `ghc -dynamic ...' (which is nice cause it avoids the 50 MB
executable),  it seg faults when it tries to call the function that it
loaded from the .o file.  Maybe I need to compile the .o with
something more than `ghc -c MyPlugin.hs'?

Rob

On Thu, Apr 7, 2011 at 3:35 PM, Don Stewart <dons00 at gmail.com> wrote:
> Perhaps look at the plugins package source?
>
> -- Don
>
> On Thu, Apr 7, 2011 at 12:20 PM, Rob Nikander <rob.nikander at gmail.com> wrote:
>> Hi all,
>>
>> I'd like to load a value from a .o file.  I've got...
>>
>> import ObjLink
>> main = do
>>  initObjLinker
>>  loadObj "Thing.o"
>>  resolveObjs
>>  Just ptr <- lookupSymbol "Thing_value_closure"
>>
>> Is that the correct symbol to load for the name "value" in module
>> "Thing"?  And if so, how to I get the haskell value out of the Ptr
>> that I get from lookupSymbol?  I found some code to do it and it works
>> value :: Int, but it seg faults if value :: Integer, or something more
>> complex like a function.
>>
>> {-# LANGUAGE MagicHash #-}
>> {-# LANGUAGE UnboxedTuples #-}
>> ...
>> let !(Ptr addr) = ptr
>> in case addrToHValue# addr of
>>    (# hval #) -> hval
>>
>> Is there some documentation for this that I'm missing?  I'm looking at
>> haddock with just type signatures, like this:
>>
>> http://www.haskell.org/ghc/docs/7.0.3/html/libraries/ghc-7.0.3/ObjLink.html
>>
>> (I'm a haskell beginner.)
>>
>> thank you,
>> Rob
>>
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>