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)
rely-on-shared-lpeg-library - Do not build lpeg from source, but trust that lpeg is made available in other ways, e.g., through a system-wide installation. The loader will be replaced with a placeholder function that only emits a message.
test - Enable dependencies and/or preparations necessary to run tests (usually controlled by FEATURES=test but can be toggled independently)
