multiple_dispatch_example.rb

require 'oso'
$polar=<<POLAR
add(x: String, y: String, x.concat(y));
add(x: List,   y: List,   x.concat(y));
add(x: List,   y: String, x0.concat(y)) if x0 in x;
add(x: String, y: List,   x.concat(y0)) if y0 in y;
POLAR
class Example
  def initialize
    @o = Oso.new
    @o.load_str($polar)
  end
  def method_missing(m, *args, &block)
    z = Oso::Polar::Variable.new('z')
    args.append(z)
    @o.query_rule(m, *args).map {|b| b['z']}
  end
end
e = Example.new
raise unless e.add("foo", "bar").to_a == ["foobar"]
raise unless e.add(["foo"], "bar").to_a == ["foobar"]
raise unless e.add("foo", ["bar", "baz"]).to_a == ["foobar", "foobaz"]
raise unless e.add(["foo"], ["bar", "baz"]).to_a == [["foo", "bar", "baz"]]