PyHop is a simple Hierarchical Task Network (HTN) planner written in Python by Dana Nau:

PyHop 2.0 Github repo

Dana Nau's slides on HTN Planning -- PyHop and the "Travel" example are detailed

Here is a trivial port of PyHop 2.0 in Visual Studio (2019) C++14; g++ 9.3.0 will also compile and run this port (thanks to Johannes Haindl for reporting about this).

The file "MyPyHop.py" contains the python code to run the PyHop "Travel" example; the file "BlocksWorldPyHop.py" contains the python code to run both the "Travel" and the "Blocksworld" examples from PyHop.

Both "MyPyHop.py" and "BlocksWorldPyHop.py" have been tested with VS 2019 Python; I've uploaded both files so that you can compare the C++ code to the Python code.

I did my best to (i) use PyHop identifiers in the C++ code, and (ii) print exactly what and when PyHop does print something, so you should be able to follow the C++ code from the Python code.

I fixed a bug in PyHop 2.0’s blocksworld HTN which prevented me from solving IPC 2011 blocksworld problems; C++ code has been updated accordingly.