Automatic software generation based on some specification is known as program synthesis. Most existing approaches formulate program synthesis as a search problem with discrete parameters. In this paper, we present a novel formulation of program synthesis as a continuous optimization problem using an evolutionary approach, known as Covariance Matrix Adaptation Evolution Strategy. We then propose several mapping schemes to convert the continuous formulation into actual programs and propose different restart policies for the evolutionary approach. This is the first work that demonstrates the feasibility of continuous approach in synthesizing complex programs, not just simple toy programs. We compare our system, Genesys , to several recent program synthesis techniques (in both discrete and continuous domains). We find that Genesys synthesizes more programs within a fixed time budget than those existing schemes. For example, for programs of length 10, Genesys synthesizes 28% more programs than those existing schemes within the same time budget.

Probabilistic programming languages aim to separate the user-specified model from the inference runtime system, allowing users to focus on model design and leave inference to the compiler and runtime systems. However, the structure of the model can affect the inference efficiency, something that is often utilized when implementing Bayesian inference solutions without probabilistic programming. In this paper, we consider a specific class of important models within phylogenetics, which are used for tree inference. Algorithms utilizing the structures of trees in such models have been used for a long time within phylogenetics, outside the scope of probabilistic programming. In particular, the use of belief propagation can significantly speed up probabilistic tree inference when combined with other approximate inferences, such as MCMC. However, there is an open problem of how to incorporate both belief-propagation (marginalization) of a subset of latent variables in typed universal probabilistic programming languages and still be able to apply approximate inference for the rest of the variables. In this paper, we propose a solution to this problem by using an approach where a user only needs to mark which latent variables in the program should be marginalized, and the rest of the belief propagation is handled automatically. We call this approach annotated automatic pruning, acknowledging the original terminology of pruning from the phylogenetic literature. We evaluate our approach using non-trivial models for tree inference, assessing performance, and testing correctness by comparing to MrBayes as the reference implementation.