View source for Functional programming

====Referential transparency====
Pure computations yield the same value each time they are invoked. This property is called [[referential transparency]] and makes possible to conduct ''equational reasoning'' on the code. For instance if <hask>y = f x</hask> and <hask>g = h y y</hask> then we should be able to replace the definition of <hask>g</hask> with <hask>g = h (f x) (f x)</hask> and get the same result; only the efficiency might change.