jsprolog

$3

It's a simple Prolog interpreter written with TypeScript.
I've adapted it from Jan's javascript Prolog interpreter because I needed a convenient automated theorem proving engine in JavaScript.

$3

It can solve simple stuff, for instance N-queen problem. It supports tail recursion.

$3

- Parser doesn't support operators. Use function call notation: =(X, Y), is(Z, +(1, X)).
- It has a very limited set of built-in predicates.
- Current implementation is slow. Finding all solutions of N-queen problem takes about 25 seconds on Intel i5-3570.

$3

Jsprolog features rudimental support for strings:

- Double quoted text is parsed as a list of character codes.
- Use \" to mask double quote (NB: remember to escape \ as well in javascript strings: "looks \\\"pretty\\\"" )
- No built-in predicates to work with strings.
- Will be replaced with string type in future.

$3

``
npm i jsprolog
`

Please note that the project is far from stabilization and the API will surely change at some point in the future.

`javascript
var Prolog = require('jsprolog');
var db = Prolog.Parser.parse("member(X,[X|R]). member(X, [Y | R]) :- member(X, R)."),
query = Prolog.Parser.parseQuery("member(X,[a,b,c]),member(Y,[1,2,3])."),
iter = Prolog.Solver.query(db, query);
while(iter.next()){
console.log("X = ", iter.current.X, ", Y = ", iter.current.Y);
}
``

Also refer to specs/prologSolverSpec.js for usage examples.

$3

Predicate | Notes
----------| -------------------------------------------------
=/2 | Doesn't support cyclic terms.
!/0 |
fail/0 |
call/1 |
findall/3 |
is/2 | Supports only +,-,/,*. Silently fails on error.