[Haskell-cafe] Problem when installing gtk2hs.

[Magicloud Magiclouds]

Hi, I have met similar problem before, and I do not know what to do.

# cabal install --reinstall gtk2hs-buildtools
Resolving dependencies...
Configuring gtk2hs-buildtools-0.9...
cabal: alex is required but it could not be found.
cabal: Error: some packages failed to install:
gtk2hs-buildtools-0.9 failed during the configure step. The exception was:
ExitFailure 1
# alex -v
Alex version 2.3.3, (c) 2003 Chris Dornan and Simon Marlow
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