how to call lambdas without call()

One thing that is rather nifty in javascript is the ability to assign anonymous functions to variables and then simply call them. For example, Protovis has this nifty method for creating a mapping function from the specified domain to the specified range:

var y = pv.Scale.linear(0, 100).range(0, 640);
y(100);  // 640
y(0);    // 0
y(50);   // 320

Neat!! Well, how about Ruby?

Well, I've been reading Metaprogramming Ruby (which is a really fun book so far) and we have lambdas. However, with a lambda, you usually have assign the lambda and then call() the lambda.

It looks like this:

f = lambda {|x| x}
f.call(10)  # 10

But I wanted this to be more like javascript's syntax, so I did some tinkering. Here's what I came up with:

	# 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)

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