Markov Chain Monte Carlo for program synthesis isn't exactly novel. The most immediate reference I thought of is Josh Tenenbaum's [1].
There's also a lot of demos in WebPPL (web probabilistic programming language)[2] like [3] for the synthesis of 3D space-ships. I highly recommend their associated books on The Design and Implementation of Probabilistic Programming Languages [4] and Probabilistic Models of Cognition [5].
I also highly recommend taking a look at the publications of the MIT Probabilistic Computing Project [6].