Resolving dependencies...
cabal: Could not resolve dependencies:
next goal: pugs-compat (user goal)
rejecting: pugs-compat-0.0.6.20150815, pugs-compat-0.0.6.20130611.0,
pugs-compat-0.0.6.20130209.0, pugs-compat-0.0.6.20120717.204800,
pugs-compat-0.0.6.20120229.163800, pugs-compat-0.0.6.20120229.160500
(constraint from user target requires ==0.0.6.20120229)
trying: pugs-compat-0.0.6.20120229
trying: base-4.9.0.0/installed-4.9... (dependency of
pugs-compat-0.0.6.20120229)
next goal: mtl (dependency of pugs-compat-0.0.6.20120229)
rejecting: mtl-2.2.1, mtl-2.2.0.1, mtl-2.2, mtl-2.1.3.1, mtl-2.1.2, mtl-2.1.1,
mtl-2.1, mtl-2.0.1.1, mtl-2.0.1.0, mtl-2.0.0.0 (conflict: pugs-compat =>
mtl<2.0.0.0)
rejecting: mtl-1.1.1.1, mtl-1.1.1.0 (conflict: base==4.9.0.0/installed-4.9...,
mtl => base<4.6)
rejecting: mtl-1.1.0.2, mtl-1.1.0.1, mtl-1.1.0.0, mtl-1.0 (conflict:
base==4.9.0.0/installed-4.9..., mtl => base<4.3)
Dependency tree exhaustively searched.