Measuring the power of programming languages

Reg Braithwaite makes an excellent argument about the importance of how well a given programming language supports us in our ability to factor our code. Factor here is used in a sense close to its mathematical meaning to do with the de-composition of numbers. For a language to be programmer friendly it must allow us to craft and re-craft our solutions into a form that is not only correct but stays that way whilst we chase our notions of elegance and improve the efficiency of the code.

To equate this ability of a language with its power I think is close to what our normal notion of power is in a language, but I don't think it quite hits the nail on the head. The reason is that to get to the stage where we can feel this aspect of the power of a language we must have been able to express our solution in it. I think that the notion of the power of a language comes earlier in our programming effort — it's about the ability of the language to allow us to express our idea in the form that we've thought of it no matter what form that is.