remote-repos: hackage.haskell.org http://hackage.haskell.org/packages/archive

...

cabal install leksah process-leksah

Resolving dependencies... cabal: Could not resolve dependencies: trying: leksah-0.15.1.4 (user goal) trying: hlint-1.9.23 (dependency of leksah-0.15.1.4) next goal: haskell-src-exts (dependency of leksah-0.15.1.4) rejecting: haskell-src-exts-1.16.0.1/installed-911... (conflict: hlint => haskell-src-exts>=1.17 && <1.18) rejecting: haskell-src-exts-1.17.0 (conflict: leksah => haskell-src-exts>=1.13.5 && <1.17) rejecting: haskell-src-exts-1.16.0.1, 1.16.0, 1.15.0.1, 1.15.0, 1.14.0.1, 1.14.0, 1.13.5 (conflict: hlint => haskell-src-exts>=1.17 && <1.18) rejecting: haskell-src-exts-1.13.4, 1.13.3, 1.13.2, 1.13.1, 1.13.0, 1.12.0, 1.11.1, 1.10.2, 1.10.1, 1.10.0, 1.9.6, 1.9.5, 1.9.4, 1.9.3, 1.9.0, 1.8.2, 1.8.1, 1.8.0, 1.7.2, 1.7.1, 1.7.0, 1.6.1, 1.6.0, 1.5.3, 1.5.2, 1.5.1, 1.5.0, 1.4.0, 1.3.5, 1.3.4, 1.3.3, 1.3.2, 1.3.1, 1.3.0, 1.2.0, 1.1.4, 1.1.3.1, 1.1.3, 1.1.1, 1.1.0, 1.0.1, 1.0.0, 0.5.7, 0.5.6, 0.5.5, 0.5.4, 0.5.3, 0.5.2, 0.4.8, 0.4.6, 0.4.5, 0.4.4.1, 0.4.4, 0.4.3.1, 0.4.3, 0.4.2, 0.4.1, 0.3.12, 0.3.11, 0.3.10, 0.3.9, 0.3.7, 0.3.5, 0.3.4, 0.3.3, 0.3.2, 0.2.1 (conflict: leksah => haskell-src-exts>=1.13.5 && <1.17) Backjump limit reached (change with --max-backjumps).