dev-lang/mercury
Mercury is a modern general-purpose logic/functional programming language
USE Flags
debug
Global: Enable extra debug codepaths, like asserts and extra output. If you want to get meaningful backtraces see http://www.gentoo.org/proj/en/qa/backtraces.xml
doc
Global: Adds extra documentation (API, Javadoc, etc)
emacs
Global: Adds support for GNU Emacs
examples
Global: Install examples, usually source code
java
Global: Adds support for Java
mono
Global: Build Mono bindings to support dotnet type stuff
profile
Global: Adds support for software performance analysis (will likely vary from ebuild to ebuild)
readline
Global: Enables support for libreadline, a GNU line-editing library that almost everyone wants
test
Global: Workaround to pull in packages needed to run with FEATURES=test. Portage-2.1.2 handles this internally, so don't set it in make.conf/package.use anymore
threads
Global: Adds threads support for various packages. Usually pthreads
trail
* This flag is undocumented *