CL implementations are also under active development. The standard is not, but de facto standard extensions do appear occasionally (PLNs, for example). Most

CL implementations are also under active development. The standard is not, but de facto standard extensions do appear occasionally (PLNs, for example). Most things that would be language extensions in other languages can be done with libraries, though. So there's a set of what amount to de facto standard libraries people use. Too many test frameworks though. :)