This might be one for python, which I am actually familiar with, unlike julia.
It doesn't quite look like it is designed for ease of prototyping, unsure. https://github.com/randriu/synthesis # PAYNT PAYNT (Probabilistic progrAm sYNThesizer) is a tool for the automated synthesis of probabilistic programs. PAYNT takes a program with holes (a so-called sketch) and a PCTL specification (see below for more information), and outputs a concrete hole assignment that yields a satisfying program, if such an assignment exists. Internally, PAYNT interprets the incomplete probabilistic program as a family of Markov chains and uses state-of-the-art synthesis methods on top of the model checker [Storm](https://github.com/moves-rwth/storm) to identify satisfying realization. PAYNT is implemented in python and uses [Stormpy](https://github.com/moves-rwth/stormpy), python bindings for Storm. This repository contains the source code of PAYNT along with adaptations for Storm and Stormpy, prerequisites for PAYNT. PAYNT is hosted on [github](https://github.com/gargantophob/synthesis).
