$ cabal install lens
Resolving dependencies...
Configuring base-orphans-0.4.4...
Configuring prelude-extras-0.4.0.2...
Building base-orphans-0.4.4...
Building prelude-extras-0.4.0.2...
Configuring reflection-2.1...
Installed base-orphans-0.4.4
Building reflection-2.1...
Configuring tagged-0.8.2...
Installed prelude-extras-0.4.0.2
Building tagged-0.8.2...
Installed tagged-0.8.2
Configuring distributive-0.4.4...
Configuring semigroups-0.18.0.1...
Installed reflection-2.1
Building semigroups-0.18.0.1...
Installed semigroups-0.18.0.1
Configuring bifunctors-5.1...
Building bifunctors-5.1...
Building distributive-0.4.4...
Configuring void-0.7.1...
Installed distributive-0.4.4
Building void-0.7.1...
Installed void-0.7.1
Configuring contravariant-1.3.3...
Installed bifunctors-5.1
Building contravariant-1.3.3...
Installed contravariant-1.3.3
Configuring comonad-4.2.7.2...
Building comonad-4.2.7.2...
Installed comonad-4.2.7.2
Configuring profunctors-5.1.2...
Configuring semigroupoids-5.0.0.4...
Building profunctors-5.1.2...
Building semigroupoids-5.0.0.4...
Installed profunctors-5.1.2
Installed semigroupoids-5.0.0.4
Configuring free-4.12.1...
Building free-4.12.1...
Installed free-4.12.1
Configuring adjunctions-4.2.2...
Building adjunctions-4.2.2...
Installed adjunctions-4.2.2
Configuring kan-extensions-4.2.3...
Building kan-extensions-4.2.3...
Installed kan-extensions-4.2.3
Configuring lens-4.13...
Building lens-4.13...
Installed lens-4.13