Paul Tarau's iProlog

License: Apache 2.0

Todo

Better type names in util folder.
Move parser from Engine.loadProgram into a ANTLR4 based compiler
MyIntList looks a bit ugly
Add code documentation
Add unit tests
Finish docker-compose to be able to build and run it without installing Java 16 or SWI-Prolog.
Can we use lazy streams instead of fully resolved list and arrays, thus only pulling the data that is really needed in each iteration?
Encapsulate tag / symbol / value resolution in a different class

doc/paper.pdf (A Hitchhiker's Guide to Reinventing a Prolog Machine)
tutorial at VMSS'16 for some motivations for this and justification of implementation choices a swi prolog script first compiles the code to a pl.nl file, than Main calls stuff in Engine which loads it in memory and runs it

see main code (~1000lines) in Engine.java

pl2nl.pl compiles a .pl file to its .nl equivalent, ready to run by the java based runtime system
natint.pl emulates its work by compiling back .nl files to Prolog clauses

no symbol tables: a symbol is just a (small) ground array of ints, and instead of a symbol table we would have a "ground cache" - that helps with better memory usege and also speed
when a non-ground compound tries to unify with a ground, the ground term is expanded to the heap
when a ground unifies with a ground - it's just pointer equality and when a var unifies with a ground, it just points to it - as if it were a constant