Resolving dependencies...
cabal: Could not resolve dependencies:
trying: sylvia-0.2.2 (user goal)
next goal: transformers (dependency of sylvia-0.2.2)
rejecting: transformers-0.3.0.0/installed-16a... (conflict: mtl =>
transformers==0.4.*)
trying: transformers-0.4.3.0
next goal: optparse-applicative (dependency of sylvia-0.2.2)
rejecting: optparse-applicative-0.11.0.2, 0.11.0.1, 0.11.0, 0.10.0, 0.9.1.1,
0.9.1, 0.9.0, 0.8.1, 0.8.0.1, 0.8.0, 0.7.0.2, 0.7.0.1, 0.7.0, 0.6.0, 0.5.2.1,
0.5.2, 0.5.1, 0.5.0 (conflict: sylvia => optparse-applicative==0.4.*)
rejecting: optparse-applicative-0.4.3, 0.4.2, 0.4.1, 0.4.0 (conflict:
transformers==0.4.3.0, optparse-applicative => transformers>=0.2 && <0.4)
rejecting: optparse-applicative-0.3.2, 0.3.1, 0.3.0, 0.2.0, 0.1.1, 0.1.0,
0.0.1 (conflict: sylvia => optparse-applicative==0.4.*)
Backjump limit reached (change with --max-backjumps).