Resolving dependencies...
cabal: Could not resolve dependencies:
next goal: pugs-compat (user goal)
rejecting: pugs-compat-0.0.6.20150815, 0.0.6.20130611.0, 0.0.6.20130209.0,
0.0.6.20120717.204800, 0.0.6.20120229.163800, 0.0.6.20120229.160500 (global
constraint requires ==0.0.6.20120229)
trying: pugs-compat-0.0.6.20120229
trying: base-4.8.1.0/installed-4f7... (dependency of
pugs-compat-0.0.6.20120229)
next goal: mtl (dependency of pugs-compat-0.0.6.20120229)
rejecting: mtl-2.2.1, 2.2.0.1, 2.2, 2.1.3.1, 2.1.2, 2.1.1, 2.1, 2.0.1.1,
2.0.1.0, 2.0.0.0 (conflict: pugs-compat => mtl<2.0.0.0)
rejecting: mtl-1.1.1.1, 1.1.1.0 (conflict: base==4.8.1.0/installed-4f7..., mtl
=> base<4.6)
rejecting: mtl-1.1.0.2, 1.1.0.1, 1.1.0.0, 1.0 (conflict:
base==4.8.1.0/installed-4f7..., mtl => base<4.3)
Dependency tree exhaustively searched.