Resolving dependencies...
cabal: Could not resolve dependencies:
next goal: system-fileio (user goal)
rejecting: system-fileio-0.3.16.3, 0.3.16.2, 0.3.16.1, 0.3.16, 0.3.15, 0.3.14,
0.3.13, 0.3.12, 0.3.11, 0.3.10, 0.3.9, 0.3.8, 0.3.7, 0.3.6, 0.3.5 (global
constraint requires ==0.3.4)
trying: system-fileio-0.3.4
trying: base-4.8.1.0/installed-4f7... (dependency of system-fileio-0.3.4)
next goal: unix (dependency of system-fileio-0.3.4)
rejecting: unix-2.7.1.0/installed-643..., 2.7.1.0, 2.7.0.1, 2.7.0.0, 2.6.0.1,
2.6.0.0 (conflict: system-fileio => unix>=2.3 && <2.6)
rejecting: unix-2.5.1.1, 2.5.1.0 (conflict: base==4.8.1.0/installed-4f7...,
unix => base>=4.5 && <4.6)
rejecting: unix-2.5.0.0 (conflict: base==4.8.1.0/installed-4f7..., unix =>
base>=4.2 && <4.5)
rejecting: unix-2.4.2.0, 2.4.1.0 (conflict: base==4.8.1.0/installed-4f7...,
unix => base>=4.2 && <4.4)
rejecting: unix-2.4.0.2, 2.4.0.1 (conflict: base==4.8.1.0/installed-4f7...,
unix => base>=4.2 && <4.3)
rejecting: unix-2.4.0.0 (conflict: base==4.8.1.0/installed-4f7..., unix =>
base>=4.1 && <4.3)
rejecting: unix-2.3.2.0, 2.3.1.0, 2.3.0.0 (conflict:
base==4.8.1.0/installed-4f7..., unix => base<4.3)
rejecting: unix-2.2.0.0, 2.0 (conflict: system-fileio => unix>=2.3 && <2.6)
Dependency tree exhaustively searched.