Resolving dependencies...
cabal: Could not resolve dependencies:
next goal: pgdl (user goal)
rejecting: pgdl-10.5, pgdl-10.4, pgdl-10.3, pgdl-10.2, pgdl-10.0, pgdl-9.3,
pgdl-9.2, pgdl-9.1, pgdl-8.5, pgdl-8.4, pgdl-8.3, pgdl-8.2, pgdl-8.1,
pgdl-8.0, pgdl-7.77, pgdl-7.6, pgdl-7.5, pgdl-7.4, pgdl-7.3, pgdl-7.0,
pgdl-6.9, pgdl-6.8, pgdl-6.7, pgdl-6.6, pgdl-6.5, pgdl-9.0 (constraint from
user target requires ==6.4)
trying: pgdl-6.4
next goal: base (dependency of pgdl-6.4)
rejecting: base-4.9.0.0/installed-4.9... (conflict: pgdl => base==4)
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.