[Haskell-cafe] Haskell Platform install instructions

[Michael Snoyman]

Hi everyone,

Some of the dependencies for Yesod (such as haskell-src) require
happy. For the "Yesod in Five Minutes" page[1], I've given
instructions to cabal install happy and then cabal install yesod.
However, as Xavier Shay pointed out to me, this won't actually work on
a vanilla install, since happy gets installed in the cabal bin folder,
which is not by default on the PATH. Two questions:

* Should we document this somewhere in the Haskell Platform install
process? I'm sure many old-time users of cabal are well aware that
they need ~/.cabal/bin in the PATH, but new users will not be. I would
also like to update Yesod's documentation; does anyone have standard
phrasing that is applicable to all operating systems?
* Should we consider modifying the build tools to automatically look
for build dependencies in the cabal bin folder?

Michael

[1] http://docs.yesodweb.com/five-minutes