Nice article! Something along these lines is still present, I think, in HtDP, at least in the Chapter about abstractions (16.1, 16.5, and 16.6). Basically, wh

Nice article! Something along these lines is still present, I think, in HtDP, at least in the Chapter about abstractions (16.1, 16.5, and 16.6). Basically, when designing a function one can use existing abstractions (or, I would add, design her own abstraction) whose whole signature, output included, matches the purpose and signature of the function to be designed. So, if the problem at hand is to design a function that takes a natural number and produces a list, that calls for using the built-in `build-list`, whose signature is `N [N -> X] -> [List-of X]`. Or if the output of a function on lists is a Boolean value, one has to keep an eye on `ormap`/`andmap`, etc. So the output is also essential to choose the suitable abstraction.