In a couple of videos Brian Beckman has mentioned that he uses  Mathematica to design and test functions (and maybe algorithms).  I'm curious about what he means by designing functions in this way.  

The latest Beckman Meijer Overdrive, The Lambda Calculus, General Term Rewriting and Food Nutrition, mentions creating or converting from another language  a function in Mathematica to ensure that it's a "good" function, then converting it to  the production language such as C.  Is that what he has designing functions in Mathematica, or is their more to it.