This is a simplified Warren Abstract Machine (WAM) implementation for Prolog, that showcases the main instructions, compiling, register allocation and machine functions.

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1. About Prolog: a hurried primer if you don't know what it is about.
2. Resolution strategy: how a query is actually solved in Prolog.
3. Warren Abstract Machine: details about the implementation attempted here.
4. Indexing: indexing implementation to fast-track some call patterns.
5. Parsing: explaining basic structures for parsing
6. Grammar: documentation for the sample application of grammar parsing.
7. Stuff left out: what this implementation has simplified from the WAM, and references.

• model.py: Data objects representing terms, programs, and machine entities.
• compiler.py: Compiling of a list of rules into a list of instructions.
• interpreter.py: Interpreter that execute the instruction listing for a given query.
• grammar.py: Sample application of interpreter, with a grammar that can parse itself. Try it out with python -m grammar and compare with the text in the file!

After creating a Machine() object, you may set its debug_filename attribute with the name of a file where it writes the machine's internal state as a JSON for each iteration. You may visualize the execution by running an HTTP server within the debug/ folder, e.g. with python -m http.server, and loading the JSONL file.

As a sample, debugtest/interpreter.jsonl contains the execution for interpreter.py. If you wish to dump execution for some grammar tests, run pytest --debug_grammar. Warning: debug dumping is slooow.