Can't install diagrams/arithmoi on Mac

Question

I'm trying to install diagrams (in a cabal sandbox) and it fails during arithmoi installation, giving the following message :

Preprocessing library arithmoi-0.4.1.1...

no location info>:
    Warning: Couldn't figure out LLVM version!
         Make sure you have installed LLVM
ghc: could not execute: opt
Failed to install arithmoi-0.4.1.1
cabal: Error: some packages failed to install:
arithmoi-0.4.1.1 failed during the building phase. The exception was:
ExitFailure 1
diagrams-1.2 depends on arithmoi-0.4.1.1 which failed to install.
diagrams-contrib-1.1.2 depends on arithmoi-0.4.1.1 which failed to install.

I'm not sure why I don't have LLVM backend installed or why It could execute opt. Any idea ? (I'm using GHC 7.6.3 on OS 10.8)

Answer 1

You can build arithmoi without LLVM by using cabal install arithmoi -f -llvm.