A μKanren implementation in PureScript.

import Kanren
-- q is 5 or q is 6
run do
  q ← fresh
  q ?== 5 ?|| q ?== 6
-- [5,6] (two answers)
-- q is 5 and q is 6 (impossible)
run do
  q ← fresh
  q ?== 5 ?&& q ?== 6
-- [] (no answers)
import Data.Array ((..))
-- a and b appended are 1..6
run do
  q ← fresh
  a ← fresh
  b ← fresh
  q ?== [a, b]
  appendo a b (1..6)
-- [[[],[1,2,3,4,5,6]],
--  [[1],[2,3,4,5,6]],
--  [[1,2],[3,4,5,6]],
--  [[1,2,3],[4,5,6]],
--  [[1,2,3,4],[5,6]],
--  [[1,2,3,4,5],[6]],
--  [[1,2,3,4,5,6],[]]]

The amount of data types available are restricted by the LogicValue implementation: strings, integers, and cons lists only.

Copyright 2016 Bodil Stokke

This program is free software: you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along with this program. If not, see https://www.gnu.org/licenses/.