Developer Ales Tsurko has released a free VST plugin, Kotoist, designed for live coding and algorithmic composition.
Kotoist is designed to let you to compose music on-the-fly, using the Koto language. Koto is scripting language, developed by Ian Hobson (ex-Ableton) for creative coding. Kotoist also has a library of patterns, ported from SuperCollider.
“I haven’t found a plugin like this,” notes Tsurko, “so I wrote my own.”