[Haskell-beginners] ghc-mod and cabal "could not find module Prelude"

[Alan Buxton]

Hi

 

I've recently set up a new Haskell working environment on Ubuntu 14.04. I
installed the Ubuntu packaged version of Haskell platform.

 

My problem is that I can't now get ghc-mod check to work if there is a cabal
file in the current directory.

 

 

I am using:

*       ghc-mod 5.2.1.2 compiled by GHC 7.6.3

*       cabal 1.16.0.2

 

See below an extract of trying to run ghc-mod check in a directory that was
empty until I just ran cabal init in it:

 

~/tmp-ghc-mod$ ls

Setup.hs  tmp-ghc-mod.cabal

~/tmp-ghc-mod$ ghc-mod check Setup.hs 

Setup.hs:1:1:Could not find module `Prelude'It is a member of the hidden
package `base'.Perhaps you need to add `base' to the build-depends in your
.cabal file.It is a member of the hidden package `haskell98-2.0.0.2'.Perhaps
you need to add `haskell98' to the build-depends in your .cabal file.It is a
member of the hidden package `haskell2010-1.1.1.0'.Perhaps you need to add
`haskell2010' to the build-depends in your .cabal file.Use -v to see a list
of the files searched for.

~/tmp-ghc-mod$ mv tmp-ghc-mod.cabal tmp-ghc-mod.cabal.NOT

~/tmp-ghc-mod$ ls

dist  Setup.hs  tmp-ghc-mod.cabal.NOT

~/tmp-ghc-mod$ ghc-mod check Setup.hs

Setup.hs:2:1:Warning: Top-level binding with no type signature: main :: IO
()

~/tmp-ghc-mod$ 

 

So. ghc-mod behaves as expected when there is no cabal file, but doesn't
behave as expected if there is a cabal file.

 

My google fu isn't helping me out on this: the only issues I have seen are
to do with a change in format of the cabal file in newer versions of cabal.

 

Any ideas?

 

Thanks

Alan

 

 

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