I dunno, I tried installing snap, yesod and happstack (the three top web frameworks apparently) about a month ago and after about 20 minutes of compiling all failed to install (some had missing packages, others had the packages but they failed to build). I'm running a no-frills MBP with bash, which I would imagine is a fairly popular dev environment.

All I want to do is serve an HTTP request.

I think you should figure out what's going on with with your dev environment and go with Haskell. Are you using the Haskell platform? If so I would ditch that and make sure to install everything in a sandbox, I've had very little trouble with cabal since I went with just cabal + sandboxes. I'm on linux but Chris Allen's guide has instructions for a minimal OSX install: https://github.com/bitemyapp/learnhaskell

If none of that helps, come to freenode #haskell, those packages really should work.

OK, you gave me the encouragement to try it again.

I ran into a bunch of bugs getting haskell platform set up correctly on OSX (wouldn't remove my old version, had to manually remove GHC, also reported this one https://github.com/haskell/cabal/issues/1980) but after reinstalling Haskell platform it seems to be working better. Thanks.

There is also a known issue with XCode and OS X >10.9, which may cause some packages to fail to compile. Haskell Platform download page includes instructions on how to avoid it: http://www.haskell.org/platform/mac.html

If you are using the GHC and Haskell-Plataform provided by your distro, I'd recommend you get the latest version and install it yourself. Both are changing a lot and some distros (Debian, for example) do not keep up. (Also, that'll avoid a few severe bugs GHC had up to a few years ago.)