On 2/9/06, Frederico Franzosi
I'm developping a package wich imports C functions.
For example if I use: $ghc -package PKGname-PKGversion -fffi -o main Main.hs -llib
it gives an error message (undefined references of objects from PKG to functions in lib)
I don't have exact answer, but ghc uses ld under the hood and sometimes the order of libraries on ld command line matters. Here's few things that might be useful if that's the case. Use ghc -v and find final link ld/gcc (I don't recall which one ghc invokes for linking) and try that line yourself, you can also move libraries up on list etc to find what order you actually need. Add -llib to the options in package.conf as a library- try adding as first and try adding as last. Try both ;-) Try adding as object file, ie /path/to/lib.a Order of arguments on ghc command line doesn't matter so much, because ghc will put (if I recall correctly) package libraries first and then add -llib and such options to the end on the ld command line- so it's pretty hard to work around the problem just by invoking ghc different way.
$ghc -fffi -o main Main.hs -llib /path/to/PKGlib.a
it compiles correctly.
and also when I do:
$ghc -package PKGname-PKGversion -fffi -o main Main.hs /path/to/lib.a
If I were to guess these work because /path/to/lib.a is handled as an object file, which is somehow different from being library. I have no knowledge what and why there is this sort of magic restrictions. HTH, -Esa