Resolving dependencies... cabal: Could not resolve dependencies: trying: plivo-0.2.0.0 (user goal) next goal: unexceptionalio (dependency of plivo-0.2.0.0) rejecting: unexceptionalio-0.3.0, unexceptionalio-0.2.0 (conflict: plivo => unexceptionalio<0.2.0) trying: unexceptionalio-0.1.0 trying: transformers-0.5.2.0/installed-0.5... (dependency of unexceptionalio-0.1.0) next goal: errors (dependency of plivo-0.2.0.0) rejecting: errors-2.1.3, errors-2.1.2 (conflict: unexceptionalio==0.1.0, errors => unexceptionalio>=0.3 && <0.4) rejecting: errors-2.1.1, errors-2.1.0, errors-2.0.1 (conflict: transformers==0.5.2.0/installed-0.5..., errors => transformers>=0.2 && <0.5) rejecting: errors-2.0.0 (conflict: transformers==0.5.2.0/installed-0.5..., errors => transformers>=0.4 && <0.5) rejecting: errors-1.4.7 (conflict: transformers==0.5.2.0/installed-0.5..., errors => transformers>=0.2 && <0.5) rejecting: errors-1.4.6, errors-1.4.5, errors-1.4.4, errors-1.4.3, errors-1.4.2 (conflict: transformers==0.5.2.0/installed-0.5..., errors => transformers>=0.2 && <0.4) rejecting: errors-1.4.1, errors-1.4.0, errors-1.3.1, errors-1.3.0, errors-1.2.1, errors-1.2.0, errors-1.1.1, errors-1.1.0, errors-1.0.0 (conflict: unexceptionalio => errors>=1.4.2) Dependency tree exhaustively searched.