ukanren.net's Introduction

uKanren.NET

A native implementation of the MicroKanren logic programming DSL for .NET. The paper describing the original Scheme implementation is here:

http://webyrd.net/scheme-2013/papers/HemannMuKanren2013.pdf

Examples

Variable x may equal either 5 or 6:

public static Goal Simple()
{
    return Kanren.Exists(x => x == 5 | x == 6);
}
...

var y = Simple().Search(Kanren.EmptyState);
Print(y);

//output:
//x[0] = 5,
//x[0] = 6,

Variable x may equal 5, and y may equal 5 or 6:

public static Goal SimpleConjunction()
{
    return Kanren.Exists(x => x == 5)
         & Kanren.Exists(y => y == 5 | y == 6);
}
...
var y = SimpleConjunction().Search(Kanren.EmptyState);
Print(y);

//output:
//x[0] = 5, y[0] = 6,
//x[0] = 5, y[0] = 5,

Variable x may equal 1 and 9:

static Goal OneAndNine(Kanren x)
{
    return x == 1 & x == 9;
}
...
var y = Kanren.Exists(OneAndNine).Search(Kanren.EmptyState);
Print(y);

//output:

Recursive equation where variable may equal 5:

static Goal Fives(Kanren x)
{
    return x == 5 | Kanren.Recurse(Fives, x);
}
...
var y = Kanren.Exists(Fives).Search(Kanren.EmptyState);
Print(y);

//output:
//x[0] = 5,
//x[0] = 5, x[0] = 5, x[0] = 5, [stream continues]

Resolve variables within arrays:

static Goal DoublyNestedArray()
{
    return Kanren.Exists(x => x == new[] { 3, 99 }
		 & Kanren.Exists(z => z == new object[] { x, 2, 9 }));
}
...
var y = Kanren.Exists(DoublyNestedArrays).Search(Kanren.EmptyState);
Print(y);

//output:
//x[0] = [3, 99], z[1] = [[3, 99], 2, 9]