This is a very short article to make you notice that al received two important changes:
I tested the latter with a Windows 64b:
cabal update cabal install al
That’s all. You should try it out as well. If you have errors about OpenAL libraries and/or header files, check whether OpenAL is correctly installed. If the error comes up again, proceed as I said here.
Also, I take people on linux feedback about installs ;).