Warning: The install command is a part of the legacy v1 style of cabal usage.

Please switch to using either the new project style and the new-install
command or the legacy v1-install alias as new-style projects will become the
default in the next version of cabal-install. Please file a bug if you cannot
replicate a working v1- use case with the new-style commands.

For more information, see: https://wiki.haskell.org/Cabal/NewBuild

Resolving dependencies...
Warning: The following packages are likely to be broken by the reinstalls:
parsec-3.1.13.0
Cabal-2.4.0.1
Continuing even though the plan contains dangerous reinstalls.
Starting     semigroups-0.19
Starting     transformers-0.5.6.2
Starting     hashable-1.3.0.0
Building     semigroups-0.19
Building     hashable-1.3.0.0
Building     transformers-0.5.6.2
Completed    semigroups-0.19
Completed    hashable-1.3.0.0
Completed    transformers-0.5.6.2
Starting     transformers-compat-0.6.5
Starting     mtl-2.2.2
Building     mtl-2.2.2
Building     transformers-compat-0.6.5
Completed    transformers-compat-0.6.5
Completed    mtl-2.2.2
Starting     constraints-0.11
Building     constraints-0.11
Completed    constraints-0.11
Downloading  effect-stack-0.3
Downloaded   effect-stack-0.3
Starting     effect-stack-0.3
Building     effect-stack-0.3
Completed    effect-stack-0.3