contravariant

USE flags

• doc - Add extra documentation (API, Javadoc, etc). It is recommended to enable per package instead of globally
• hscolour - Include coloured haskell sources to generated documentation (dev-haskell/hscolour)
• profile - Add support for software performance analysis (will likely vary from ebuild to ebuild)
• semigroups - You can disable the use of the `semigroups` package using `-f-semigroups`. Disabling this is an unsupported configuration, but it may be useful for accelerating builds in sandboxes for expert users.
• statevar - You can disable the use of the `StateVar` package using `-f-StateVar`. Disabling this is an unsupported configuration, but it may be useful for accelerating builds in sandboxes for expert users.
• tagged - You can disable the use of the `tagged` package on older versons of GHC using `-f-tagged`. Disabling this is an unsupported configuration, but it may be useful for accelerating builds in sandboxes for expert users.