Resolving dependencies...
cabal: Could not resolve dependencies:
next goal: scan (user goal)
rejecting: scan-0.1.0.9, scan-0.1.0.8, scan-0.1.0.7, scan-0.1.0.6,
scan-0.1.0.5, scan-0.1.0.4 (constraint from user target requires ==0.1.0.3)
trying: scan-0.1.0.3
trying: base-4.9.0.0/installed-4.9... (dependency of scan-0.1.0.3)
next goal: parsec (dependency of scan-0.1.0.3)
rejecting: parsec-3.1.11, parsec-3.1.10, parsec-3.1.9, parsec-3.1.8,
parsec-3.1.7, parsec-3.1.6, parsec-3.1.5, parsec-3.1.4, parsec-3.1.3,
parsec-3.1.2, parsec-3.1.1, parsec-3.1.0, parsec-3.0.1, parsec-3.0.0
(conflict: scan => parsec<3)
rejecting: parsec-2.1.0.1, parsec-2.1.0.0, parsec-2.0 (conflict:
base==4.9.0.0/installed-4.9..., parsec => base<4.8)
Dependency tree exhaustively searched.