Tiny-Prolog-in-OCaml

A tiny implementation of a small subset of the Prolog language, in OCaml. With small and fun examples.

WARNING: this project only has an educational purpose, for a real-world use of Prolog, please refer to GNU Prolog (gprolog).

This project contains the code and examples for a tiny Prolog implementation, written in the OCaml language.

• See this folder for instructions to build the project (really easy: clone, run make, relax and enjoy 🎉). The implementation focuses on a very small subset of Prolog, see the examples for a good idea of what is supported.
• See this other folder for examples (in English).

Example

• A theory has this form, first with axioms (predicate):

cat(tom).
mouse(jerry).

• Then maybe some rules, stating that a mouse is fast and a cat can be stupid:

fast(X) <-- mouse(X).
stupid(X) <-- cat(X).

• If you save this file (see this example), you can then load it with the prolog binary:

$ ./prolog/prolog ./examples/tomandjerry.pl
?- stupid(tom).
  { }
continue ? (o/n) [o] :

• This { } is an empty model, meaning that stupid(tom). evaluates to True in an empty model (no need for instanciation).
• You can also ask your question directly in the command line:

$ ./prolog/prolog ./examples/tomandjerry.pl "fast(tom)."
?- fast(tom).

• An empty response mean that the term is false, no matter the model.

• You can add more rules, as you want.

ishuntedby(X, Y) <-- mouse(X), cat(Y).

$ ./prolog/prolog ./examples/tomandjerry.pl "ishuntedby(tom, jerry)."
?- ishuntedby(tom, jerry).
$ ./prolog/prolog ./examples/tomandjerry.pl "ishuntedby(jerry, tom)."
?- ishuntedby(jerry, tom).
  { }

• You can also add comments, that are lines starting with one or more # character.

# the mouse always espace the cat!
istrickedby(X, Y) <-- cat(X), mouse(Y).

More example

• See this folder,
• Or this notebook.

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📜 License ?

This (small) repository is published under the terms of the MIT license (file LICENSE). © Lilian Besson, 2018.