Resolving dependencies...
cabal: Could not resolve dependencies:
next goal: grammar-combinators (user goal)
rejecting: grammar-combinators-0.2.7, grammar-combinators-0.2.6,
grammar-combinators-0.2.5, grammar-combinators-0.2.4,
grammar-combinators-0.2.3, grammar-combinators-0.2.2,
grammar-combinators-0.2.1 (constraint from user target requires ==0.2)
trying: grammar-combinators-0.2
trying: base-4.9.0.0/installed-4.9... (dependency of grammar-combinators-0.2)
next goal: MaybeT (dependency of grammar-combinators-0.2)
rejecting: MaybeT-0.1.2 (conflict: base==4.9.0.0/installed-4.9..., MaybeT =>
base<4.8)
rejecting: MaybeT-0.1.1, MaybeT-0.1.0 (conflict: grammar-combinators =>
MaybeT>=0.1.2)
Dependency tree exhaustively searched.