It has been called Perl's killer app.[16] It is roughly equivalent to the PECL and PEAR for PHP; the PyPI (Python Package Index) repository for Python; RubyGems for Ruby; CRAN for R; npm for Node.js; LuaRocks for Lua; Maven for Java; and Hackage for Haskell. CPAN's use of arbitrated name spaces, a testing regime and a well defined documentation style makes it unique.