logic_ts

import logic from "https://deno.land/x/logic_ts/mod.ts";

const { lvar, run, and, or, eq } = logic; // or `logic` in browser

const x = lvar("x"); // define logic variable with id 'x'

run(1, [x], eq(x, 1)); // query 'x' => [{x: 1}]
run(1, [x], (y = lvar()) =>
  and(
    eq(y, 1),
    eq(x, y),
  )); // => [{x: 1}]

run([x], or(eq(x, 1), eq(x, 2))); // [{x: 1}, {x: 2}]
run([x], or(1, eq(x, 1), eq(x, 2))); // [{x: 1}]

const { facts } = logic;
// FACT
const parent = facts(["Steve", "Bob"], // Steve is Bob's parent
["Steve", "Henry"], // Steve is Henry's parent
["Henry", "Alice"]); // Henry is Alice's parent
const x = lvar();
run(1, [x], parent(x, "Alice")); // who is Alice's parent => ['Henry']
run(2, [x], parent("Steve", x)); // who are Steve's children => ['Bob', 'Henry']

// RULE
const grandparent = (x: any, y: any) => {
  let z = lvar();
  return and(parent(x, z), parent(z, y)); // x is z's parent and z is y's parent => x is y's parent
};

run(1, [x], grandparent(x, "Alice")); // who is Alice's grandparent => ['Steve']

const { conso, firsto, resto, emptyo, membero, appendo } = logic;

const x = lvar("x"),
  y = lvar("y");

run([x], membero(x, [1, 2, 3]));
// [{x: 1}, {x: 2}, {x: 3}]

run([x, y], conso(x, y, [1, 2, 3]));
// [{x: 1, y: [2, 3]}]

run([x, y], appendo(x, y, [1, 2]));
/*
[ {x: [], y: [1, 2]},
{x: [1], y: [2]}
{x: [1, 2], y: []} ]
*/

const { add, sub, mul, div, lt, le, gt, ge } = logic;

run([x], add(2, x, 5));
// [{x: 3}]

const { succeed, fail, anyo } = logic;

run([x], and(eq(x, 1), succeed()));
// [{x: 1}]

run([x], and(eq(x, 1), fail()));
// []

run(
  [x],
  or(
    eq(x, 1),
    eq(x, 2),
    eq(x, 3),
  ),
); // [{x: 1}, {x: 2}, {x: 3}]

run(
  [x],
  or(
    eq(x, 1),
    and(eq(x, 2), fail()),
    eq(x, 3),
  ),
); // [{x: 1}, {x: 3}]

run(4, [x], anyo(or(eq(x, 1), eq(x, 2), eq(x, 3))));
// [{x: 1}, {x: 2}, {x: 3}, {x: 1}]