gistfile1.cs

/* Referential Transparency (RT), from http://dl.dropbox.com/u/7810909/docs/what-does-fp-mean/index.html

Program 1:
X x = function(args);
R r1 = arbitrary(x);
R r2 = arbitrary(x);

Program 2:
R r1 = arbitrary(function(args));
R r2 = arbitrary(function(args));

If 1 and 2 produce the same outcome then x is RT.
*/

Func<string,Action> writeLine = s => () => Console.WriteLine(s);
Func<Func<string,Action>,Action> arbitrary = f => f("Hello");

//First case:
var x = writeLine;
var r1 = arbitrary(x); // r1() will print "Hello"
var r2 = arbitrary(x); // r2() will print "Hello"

//Second case:
var r1 = arbitrary(writeLine);  // r1() will print "Hello"
var r2 = arbitrary(writeLine);  // r1() will print "Hello"