MyDef is not really a programming language, but a meta layer. Sounds like a new concept but it is more like cpp or m4 in the toolchain point of view. As such, it can work with any programming languages. e.g. In the Nim example, every thing written is Nim, except the macro; and MyDef itself is actually in 100% Perl (the bootstrap folder is actually a pure Perl package). However, specific extension/plugin also can be written for specific language to customize and gain special power; I did that for Perl and C.