Resolving dependencies...
cabal: Could not resolve dependencies:
next goal: JsonGrammar (user goal)
rejecting: JsonGrammar-1.0.3, 1.0.2, 1.0.1, 1.0, 0.3.5, 0.3.4, 0.3.3, 0.3.2
(global constraint requires ==0.3.1)
trying: JsonGrammar-0.3.1
next goal: base (dependency of JsonGrammar-0.3.1)
rejecting: base-4.8.1.0/installed-4f7... (conflict: JsonGrammar => base>=3.0
&& <4.5)
rejecting: base-4.8.1.0, 4.8.0.0, 4.7.0.2, 4.7.0.1, 4.7.0.0, 4.6.0.1, 4.6.0.0,
4.5.1.0, 4.5.0.0, 4.4.1.0, 4.4.0.0, 4.3.1.0, 4.3.0.0, 4.2.0.2, 4.2.0.1,
4.2.0.0, 4.1.0.0, 4.0.0.0, 3.0.3.2, 3.0.3.1 (global constraint requires
installed instance)
Dependency tree exhaustively searched.