Resolving dependencies...
cabal: Could not resolve dependencies:
next goal: engine-io (user goal)
rejecting: engine-io-1.2.13, engine-io-1.2.12, engine-io-1.2.11,
engine-io-1.2.10, engine-io-1.2.9 (constraint from user target requires
==1.2.8)
trying: engine-io-1.2.8
next goal: base (dependency of engine-io-1.2.8)
rejecting: base-4.9.0.0/installed-4.9... (conflict: engine-io => base<0)
rejecting: base-4.9.0.0, base-4.8.2.0, base-4.8.1.0, base-4.8.0.0,
base-4.7.0.2, base-4.7.0.1, base-4.7.0.0, base-4.6.0.1, base-4.6.0.0,
base-4.5.1.0, base-4.5.0.0, base-4.4.1.0, base-4.4.0.0, base-4.3.1.0,
base-4.3.0.0, base-4.2.0.2, base-4.2.0.1, base-4.2.0.0, base-4.1.0.0,
base-4.0.0.0, base-3.0.3.2, base-3.0.3.1 (constraint from non-upgradeable
package requires installed instance)
Dependency tree exhaustively searched.