Failing to cabal install lens

[fabriceleal]

I'm failing to install lens on a ubuntu 12.04 virtual machine. Just installed cabal and ran:

cabal install idris

and I get this:

[42 of 85] Compiling Control.Lens.Cons ( src/Control/Lens/Cons.hs, dist/build/Control/Lens/Cons.o )
[43 of 85] Compiling Control.Lens.Internal.Deque ( src/Control/Lens/Internal/Deque.hs, dist/build/Control/Lens/Internal/Deque.o )
[44 of 85] Compiling Control.Lens.At  ( src/Control/Lens/At.hs, dist/build/Control/Lens/At.o )
cabal: Error: some packages failed to install:
idris-0.9.11.2 depends on lens-4.0.4 which failed to install.
language-java-0.2.6 failed during the configure step. The exception was:
ExitFailure 1
lens-4.0.4 failed during the building phase. The exception was:
ExitFailure 139
trifecta-1.4 depends on lens-4.0.4 which failed to install.

There's an issue on idris which roots on this failure to install the latest lens
idris-lang/Idris-dev#826

[glguy]

Please verify that you're using the version of template-haskell that was installed with your GHC and that you haven't installed a new version on top of that.

You should be using template-haskell-2.8.0.0 with ghc-7.6.3 and template-haskell-2.9.0.0 only if you are using ghc-7.8.1-rc*

[fabriceleal]

It looks like I have version 7.4.1 (should I upgrade to at least ghc-7.6.3 ?)

# ghc --version
The Glorious Glasgow Haskell Compilation System, version 7.4.1

# cabal --version
cabal-install version 0.14.0
using version 1.14.0 of the Cabal library

I have template-haskell-2.8.0.0

[glguy]

When using GHC 7.4.1 you should be using template-haskell-2.7.0.0. You'll want to remove any version of template-haskell that you've installed beyond the one that GHC was distributed with.

Quoting https://www.haskell.org/ghc/docs/7.4.1/html/users_guide/release-7-4-1.html :
Section 1.7.3.22. template-haskell
Version number 2.7.0.0 (was 2.6.0.0)

[fabriceleal]

It's working! With only template-haskell-2.7.0.0 installed, I was able to install lens.