ExKanren

Relational programming in Elixir based on miniKanren.

What's new

• 2015-06-30: Overhauled CLP_Tree module, added symbolo, numbero, booleano, absento operators. Fixed erros in the stream operators. Tidied up core. Made bigger mess in CLP_FD.
• 2015-03-10: The constraint solver being used is now passed as an optional parameter to the run interface rather than being set in the process dictionary. This makes ExKanren purely functional and enables experimenting with running goals in parallel.
• 2014-09-17: Constraints over finite domains of integers now implemented
• 2014-09-09: Working through the cKanren paper, CLP(Tree) is now implemented

TODO

• Urgently need more thorough documentation
• Nominal logic

Usage

MiniKanren defines the relational and non-relational operators of miniKanren, and MiniKanren.Functions implements some of the common relations. use MiniKanren will import both MiniKanren and MiniKanren.Functions.

MiniKanren.CLP.Tree provides the tree disequality operator neq. use MiniKanren.CLP.Tree will import the operator and some common relations that rely on it, and for convenience will alias MiniKanren.CLP.Tree to CLP_Tree.

MiniKanren.CLP.FD provides operators for operations on finite domains of integers. use MiniKanren.CLP.FD will import the operator and some common relations that rely on it, and for convenience will alias MiniKanren.CLP.FD to CLP_FD.

use MiniKanren
use MiniKanren.CLP.Tree
run_all(CLP_Tree, [out, x]) do
  eq(x, [:good_night, :kittens, :good_night, :mittens,
         :good_night, :clocks, :good_night, :socks])
  rembero(:good_night, x, out)
end
# [:kittens, :mittens, :clocks, :socks]

References

This code is based on reading and figuring out a bunch of papers &c:

• miniKanren Live and Untagged: Quine Generation via Relational Interpreters
• cKanren: miniKanren with Constraints
• μKanren: A Minimal Functional Core for Relational Programming
• Relational Programming in miniKanren: Techniques, Applications, and Implementations
• core.logic