5.4.8 Style Recommendations

 

Source level optimization makes possible a clearer and more relaxed programming style:

• Don't use macros purely to avoid function call. If you want an inline function, write it as a function and declare it inline. It's clearer, less error-prone, and works just as well.
• Don't write macros that try to ``optimize'' their expansion in trivial ways such as avoiding binding variables for simple expressions. The compiler does these optimizations too, and is less likely to make a mistake.
• Make use of local functions (i.e., labels or flet) and tail-recursion in places where it is clearer. Local function call is faster than full call.
• Avoid setting local variables when possible. Binding a new let variable is at least as efficient as setting an existing variable, and is easier to understand, both for the compiler and the programmer.
• Instead of writing similar code over and over again so that it can be hand customized for each use, define a macro or inline function, and let the compiler do the work.