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Javascript porting of Paul Tarau latest Prolog Engine architecture

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hitchhicker-prolog

Javascript porting - and some small rewriting - of Paul Tarau latest Prolog Engine architecture.

The reference document: http://www.cse.unt.edu/~tarau/research/2017/eng.pdf


Some interesting properties, from the abstract:

  • the heap representation of terms and the abstract machine instruction encodings are the same
  • no dedicated code area is used as the code is placed directly on the heap
  • unification and indexing operations are orthogonal
  • filtering of matching clauses happens without building new structures on the heap
  • variables in function and predicate symbol positions are handled with no performance penalty
  • a simple English-like syntax is used as an intermediate representation for clauses and goals
  • the same English-like syntax can be used by programmers directly as an alternative to classic Prolog syntax
  • solutions of (multiple) logic engines are exposed as answer streams that can be combined through typical functional programming patterns
  • performance of a basic interpreter implementing our design is within a factor of 2 of a highly optimized WAM-based system

Ported to plain Javascript, simplifying somewhat the code. Running in Firefox, performance are about 1/3 of Java 8.

Several data structures have been replaced by arrays constructs: IntList, IntStack, IntMap, ObStack

IMap currently not (yet) used.

Available to run in browsers (see test_hhprolog_browser.html) or NodeJS (see test_hhprolog_node.js).