Links -- 2013-01-04

New for the New Year -- I will be doing some posts with links to interesting projects, posts, products. Definitely will not be daily but hopefully will be more frequent than annually! Here is the first instalment:

• Esper -- Real (or near-real?) time monitoring and reaction to events across a large systems ("complex event processing")
• Maude -- A term-rewriting system
• Ragel -- Regular expressions but with the added capability of executing code during any stage of recognition (similarity to OMeta ?)
• Hadoop on Demand -- probably an obvious one but very useful for practical map-reduce work, and helps with debugging (see this SO)
• Datomic -- a declarative, programmable, (novel) database system.
• This has been around for a while and is fairly well known, but just in case: Ceres non-linear least-squares optimiser -- written in C++, by Google.