blog: how to call lambdas without call()

lambda_no_call.rb

# inspired by the protovis library pv.Scale.linear().range()

# adapted from rspec codebase
def let(name, scale_function)
  Kernel.send :define_method, name do |p|
    scale_function.call(p)
  end
end

# returns a mapping function from the desired domain (x1,x2) to the desired range (y1,y2)
def scale(x1,x2,y1,y2)
  lambda {|p| Integer(((y2-y1)*((p-x1)/Float(x2-x1)))+y1) } unless (x2-x1) == 0
end

let(:y, scale(200,400,0,100))

puts y(200)
puts y(400)
puts y(202)

from my blog article by the same name.