I have been working on Latplan [AAAI-2018, 2,3,4,5,6], a neural-symbolic classical planning system that learns symbolic representations of noisy images and perform efficient symbolic planning in the latent space. Later, several other groups have started working in this field, like [7].
The problem with python is the lack of sequential execution speed, which is necessary for solving symbolic tasks, e.g. SAT solver, classical planning, theorem prover. At the same time, traditional languages like C++, typically used for writing solvers, are too inflexible to accommodate the workflow in machine learning. For a neural-symbolic task, personally, Lisp is best in this space (I don't try to repeat why, because there are plenty of articles on it.), with Julia being a contender.
I am also interested in adding the compile time type/shape checking on the deep learning code, since python debugging is painful (just a personal opinion -- not intending to start a war here).
By the way, I made the first prototype of this lib in 3 days, and am working on improving it for 3 month (for other ML projects).
[1] https://medium.com/@MITIBMLab/the-shared-history-and-vision-... [2] https://github.com/guicho271828/latplan [3] AAAI18 presentation at : https://asai-research-presentation.github.io/2018-2-5-aaai/ [4] AAAI18 paper : Classical Planning in Deep Latent Space: Bridging the Subsymbolic-Symbolic Boundary, https://arxiv.org/abs/1705.00154 [5] Follow-up papers (ICAPS2019) : https://arxiv.org/abs/1903.11277 [6] Follow-up papers (ICAPS2019), extension to first order logic : https://arxiv.org/abs/1902.08093 [7] Learning Plannable Representations with Causal InfoGAN, https://arxiv.org/abs/1807.09341v1