cannot install yesod

I follow installation steps given on http://www.yesodweb.com/book/TXKGPHUZXDLYRGF

the command "cabal install alex happy" fails with the error below.

what is wrong? I am totally new. this is my first attempt to install yeso开发者_JAVA百科d. I am on windows xp.

thanks for any help

Konstantin

d:>cabal install alex happy
Resolving dependencies...
cabal: Couldn't read cabal file "bytestring\0.9.2.0\bytestring.cabal"

Hackage was triggering a bug in cabal but that has been addressed. Do a cabal update and things should build now.