Justbuild, a generic build system supporting multi-repository builds

Justbuild is a generic build system supporting multi-repository builds. A peculiarity of the tool is the separation between global names and physical location on the one hand, and logical paths used for actions and installation on the other hand (sometimes referred to as "staging"). The language-specific information to translate high-level concepts (libraries, binaries) into individual compile action is taken from user-defined rules described by functional expressions.