dev$ cabal install gloss-raster

Resolving dependencies...

Configuring gloss-raster-1.8.1.2...

Building gloss-raster-1.8.1.2...

Preprocessing library gloss-raster-1.8.1.2...

[1 of 2] Compiling Graphics.Gloss.Raster.Array ( Graphics/Gloss/Raster/Array.hs, dist/build/Graphics/Gloss/Raster/Array.o )

<no location info>:

    Warning: Couldn't figure out LLVM version!

             Make sure you have installed LLVM

ghc: could not execute: opt

Failed to install gloss-raster-1.8.1.2

cabal: Error: some packages failed to install:

gloss-raster-1.8.1.2 failed during the building phase. The exception was:

ExitFailure 1