RSpec.describe Yaks::FP::Callable, "#to_proc" do
  it 'should delegate to_proc to method(:call)' do
    obj = Class.new do
      include Yaks::FP::Callable

      def call(x)
        x * x
      end
    end.new

    expect([1, 2, 3].map(&obj)).to eql [1, 4, 9]
  end
end