Resolving dependencies...
cabal: Could not resolve dependencies:
next goal: category-extras (user goal)
rejecting: category-extras-1.0.2, category-extras-1.0.1, category-extras-1.0
(constraint from user target requires ==0.53.5.1)
trying: category-extras-0.53.5.1
trying: base-4.9.0.0/installed-4.9... (dependency of category-extras-0.53.5.1)
next goal: mtl (dependency of category-extras-0.53.5.1)
rejecting: mtl-2.2.1, mtl-2.2.0.1, mtl-2.2, mtl-2.1.3.1, mtl-2.1.2, mtl-2.1.1,
mtl-2.1, mtl-2.0.1.1, mtl-2.0.1.0, mtl-2.0.0.0 (conflict: category-extras =>
mtl>=1.1 && <2)
rejecting: mtl-1.1.1.1, mtl-1.1.1.0 (conflict: base==4.9.0.0/installed-4.9...,
mtl => base<4.6)
rejecting: mtl-1.1.0.2, mtl-1.1.0.1, mtl-1.1.0.0 (conflict:
base==4.9.0.0/installed-4.9..., mtl => base<4.3)
rejecting: mtl-1.0 (conflict: category-extras => mtl>=1.1 && <2)
Dependency tree exhaustively searched.