Resolving dependencies...
cabal: Could not resolve dependencies:
next goal: yesod-core (user goal)
rejecting: yesod-core-1.4.15.1, 1.4.15, 1.4.14, 1.4.13, 1.4.12, 1.4.11.1,
1.4.11, 1.4.10, 1.4.9.1, 1.4.9, 1.4.8.3, 1.4.8.2, 1.4.8.1, 1.4.8, 1.4.7.3,
1.4.7.2, 1.4.7.1, 1.4.7, 1.4.6.2, 1.4.6.1, 1.4.6, 1.4.5, 1.4.4.5, 1.4.4.4,
1.4.4.3, 1.4.4.2, 1.4.4.1, 1.4.4, 1.4.3.1, 1.4.3, 1.4.2, 1.4.1.1, 1.4.1,
1.4.0.2, 1.4.0.1, 1.4.0, 1.2.20.1, 1.2.20, 1.2.19.2, 1.2.19.1, 1.2.19, 1.2.18,
1.2.17, 1.2.16.1, 1.2.16, 1.2.15.2, 1.2.15.1, 1.2.15, 1.2.14, 1.2.13.1 (global
constraint requires ==1.2.13)
trying: yesod-core-1.2.13
trying: exceptions-0.8.0.2 (dependency of yesod-core-1.2.13)
trying: transformers-compat-0.4.0.4 (dependency of exceptions-0.8.0.2)
trying: transformers-compat-0.4.0.4:-two
trying: transformers-compat-0.4.0.4:-three
next goal: transformers (dependency of yesod-core-1.2.13)
rejecting: transformers-0.4.2.0/installed-21d..., 0.4.3.0, 0.4.2.0, 0.4.1.0
(conflict: yesod-core => transformers>=0.2.2 && <0.4)
rejecting: transformers-0.3.0.0, 0.2.2.1, 0.2.2.0 (conflict:
transformers-compat-0.4.0.4:three => transformers>=0.4.1 && <0.5)
rejecting: transformers-0.2.1.0, 0.2.0.0, 0.1.4.0, 0.1.3.0, 0.1.1.0, 0.1.0.1,
0.1.0.0, 0.0.1.0, 0.0.0.0, 0.4.0.0 (conflict: yesod-core =>
transformers>=0.2.2 && <0.4)
Dependency tree exhaustively searched.