Bmg, Alf's successor, A Ruby Relational Algebra

Bmg is a relational algebra implemented as a ruby library. It implements the Relation as First-Class Citizen paradigm contributed with Alf a few years ago.Like Alf, Bmg can be used to query relations in memory, from various files, SQL databases, and any data sources that can be seen as serving relations. Cross data-sources joins are supported, as with Alf.Unlike Alf, Bmg does not make any core ruby extension and exposes the object-oriented syntax only (not Alf's functional one). Bmg implementation is also much simpler, and make its easier to implement user-defined relations.