Resolving dependencies...
cabal: Could not resolve dependencies:
trying: gtk2hs-rpn-0.2.1 (user goal)
trying: base-4.8.1.0/installed-4f7... (dependency of gtk2hs-rpn-0.2.1)
next goal: mtl (dependency of gtk2hs-rpn-0.2.1)
rejecting: mtl-2.2.1, 2.2.0.1, 2.2, 2.1.3.1, 2.1.2, 2.1.1, 2.1, 2.0.1.1,
2.0.1.0, 2.0.0.0 (conflict: gtk2hs-rpn => mtl>=1.1.0.2 && <1.2)
rejecting: mtl-1.1.1.1, 1.1.1.0 (conflict: base==4.8.1.0/installed-4f7..., mtl
=> base<4.6)
rejecting: mtl-1.1.0.2 (conflict: base==4.8.1.0/installed-4f7..., mtl =>
base<4.3)
rejecting: mtl-1.1.0.1, 1.1.0.0, 1.0 (conflict: gtk2hs-rpn => mtl>=1.1.0.2 &&
<1.2)
Dependency tree exhaustively searched.