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...
Starting     dual-0.1.0.2
Starting     unconstrained-0.1.0.2
Starting     base-unicode-symbols-0.2.4.2
Starting     util-0.1.14.0
Building     unconstrained-0.1.0.2
Building     dual-0.1.0.2
Building     util-0.1.14.0
Building     base-unicode-symbols-0.2.4.2
Completed    unconstrained-0.1.0.2
Completed    dual-0.1.0.2
Completed    base-unicode-symbols-0.2.4.2
Completed    util-0.1.14.0
Starting     exist-0.2.0.0
Starting     alg-0.2.12.0
Building     alg-0.2.12.0
Building     exist-0.2.0.0
Completed    exist-0.2.0.0
Completed    alg-0.2.12.0
Starting     category-0.2.4.2
Building     category-0.2.4.2
Completed    category-0.2.4.2
Starting     constraint-0.1.4.0
Building     constraint-0.1.4.0
Completed    constraint-0.1.4.0
Downloading  exist-instances-0.1.0.0
Downloaded   exist-instances-0.1.0.0
Starting     exist-instances-0.1.0.0
Building     exist-instances-0.1.0.0
Completed    exist-instances-0.1.0.0