This article is from the FAQ, by with numerous contributions by others.
The Mjolner System includes an implementation of the BETA language, a series
of libraries and application frameworks, a set of development tools, and a
metaprogramming system. All components of the Mjolner System are constructed
using the BETA language.
Major parts of the Mjolner System (e.g. the editor, parser, pretty-printer,
metaprogramming system, fragment system) are grammar-based in the sense that
tool generators exist that, given a specific grammar for a language, will
define a specific tool that is able to manipulate programs written in that