pdatastructs - Simple probabilistic data structures.

Gen - General-purpose probabilistic programming system with programmable inference.

monad-bayes - Library for probabilistic programming in Haskell.

Funsor - Functional tensors for probabilistic programming.

Pyro - Deep universal probabilistic programming with Python and PyTorch.

TensorFlow Probability - Library for probabilistic reasoning and statistical analysis in TensorFlow.

NumPyro - Probabilistic programming with NumPy powered by JAX for autograd and JIT compilation to GPU/TPU/CPU.

Edward2 - Simple probabilistic programming language.

Soss - Julia library for probabilistic programming via source rewriting.

PyMC3 - Python package for Bayesian statistical modeling and Probabilistic Machine Learning focusing on advanced Markov chain Monte Carlo (MCMC) and variational inference (VI) algorithms.

Ranked Programming - Ranked Programming Extension for Racket. Ranked programming is similar to probabilistic programming, except that the underlying uncertainty formalism is replaced with ranking theory.