Resolving dependencies...
cabal: Could not resolve dependencies:
next goal: grammar-combinators (user goal)
rejecting: grammar-combinators-0.2.7, 0.2.6 (global constraint requires
==0.2.5)
trying: grammar-combinators-0.2.5
trying: base-4.8.1.0/installed-4f7... (dependency of
grammar-combinators-0.2.5)
next goal: MaybeT (dependency of grammar-combinators-0.2.5)
rejecting: MaybeT-0.1.2 (conflict: base==4.8.1.0/installed-4f7..., MaybeT =>
base<4.8)
rejecting: MaybeT-0.1.1, 0.1.0 (conflict: grammar-combinators =>
MaybeT>=0.1.2)
Dependency tree exhaustively searched.