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)
(own answer: I case someone has the same problem) I solved it by downgrading arithmoi to 4.0.4 by adding the following line in may cabal file :
build-depend: arithmoi >= 0.4 < 0.4.1.1
Had to delete the sandbox and reinstall everything from scratch but worked at the end.