Note: This post is outdated, please refer to Cross-compiling Haskell to OMAP3 and iPhone platforms

Since I did the compilation a month ago, there could be missing pieces.

steps

• I'm using Snow Leopard (Leopard might work, not tested)
• install GHC 6.10.2 (using other version caused problem for me)
• do the Mac trick for 32bit libs
• download GHC iPhone, need the source package
• before start, briefly go through the documentation in the package (pdf)
• prepare to hack:

Everything that follows applies to both iphone and iphone simulator. I recommend prepare 2 directories to compile for iphone and iphone simulator respectively, a simple make clean might not be enough from my experience:

compilation details

OK, here's what need to be changed,

• config-iphone.sh (point every /Developer path to the current SDK)
• download required stock packages (HTTP, etc, refer to documentation) into the proper location, that is, the actually GHC source dir, where you would find README, configure etc
• start to compile. Note: compiling will fail, in particular, I had to use undefine on almost every functions from : 1. network, 2.system.direcotry. Expect to do the same.
• After compilation, follow documentation to install.

after install

• unix package is not present on my system.
• network is not usable, but it's not a big deal, NSConnection can get the job done.
• since unix is missing, it's not possible to use functions like directoryExist, fileExist and such, those abilities could be imported from Core Foundation.

dev hints

• try to see the 2 examples bundled in GHC-iPhone package, they provide valuable information to get you started. They might not compile though.
• read on haskell FFI if not already familiar, it's the primary tool to talk to the iPhone

conclude

I compiled GHC 5 times in a day on a laptop to get it working, it's not as simple as it sounds. But once it's compiled, many things work unexpectedly well, even Controll.Concurrent is working without a hassle, not to mention endless packages on Hackage.