How do I install fay?

Question

I'm running ubuntu 13.10 and I'm having trouble installing fay. I installed haskell using sudo apt-get install haskell-platform . I try cabal install fay and I receive the following message:

$ cabal install fay
Resolving dependencies...
Configuring type-eq-0.4.2...
cabal: The program cpphs is required but it could not be found.
Failed to install type-eq-0.4.2
cabal: Error: some packages failed to install:
fay-0.20.0.0 depends on type-eq-0.4.2 which failed to install.
haskell-names-0.3.3.2 depends on type-eq-0.4.2 which failed to install.
type-eq-0.4.2 failed during the configure step. The exception was:
ExitFailure 1

I tried install cpphs, but I already have it.

$ cabal install cpphs
Resolving dependencies...
All the requested packages are already installed:
cpphs-1.18.4
Use --reinstall if you want to reinstall anyway.

Finally, I tried installing type-eq by itself, and expectedly it is dependent on cpphs.

$ cabal install type-eq
Resolving dependencies...
Configuring type-eq-0.4.2...
cabal: The program cpphs is required but it could not be found.
Failed to install type-eq-0.4.2
cabal: Error: some packages failed to install:
type-eq-0.4.2 failed during the configure step. The exception was:
ExitFailure 1

What should I do? Thanks in advance for help.

Answer 1

According to comments of the original post:

1. cabal complains that cannot find already installed cpphs

2. which cpphs says command cannot be found

3. which means cpphs does not in the search paths of shell

4. add ~/.cabal/bin to PATH can be used to fix this problem