Originally posted: 2015-09-15. Modified: 2015-12-21.

People often state that python is the most similar programming language to pseudocode (what you write if you are trying to convey a piece of software to other humans rather than a computer). I've translated numerous pseudocode algorithms from books into various languages, and I agree that python often makes this process natural.

However I think an argument can also be made for LISP as the most "pseudo-code" like language. Perhaps while Python has the greatest surface similarity to pseudocode, LISP has the greatest actual similarity to pseudocode.

Why do I claim that LISP is similar to pseudocode? It's appearance is often rather different, after all.

I make this claim because of the intrinsic linguistic flexibility of a language supporting structural macros. The power of pseudocode is not just that it doesn't conform to a particular bracketing convention or function naming convention – the power of pseudocode is that you can introduce arbitrary code constructs, and explain them to your readers later on.

For example, consider the "with-redeclarations" construct, which rebinds all the functions executing within it. Lisp is MUCH closer to the ideal of the programmer being able to create arbitrary constructs than python is, and there are many instances of where you could imagine a way of thinking about a problem in pseudocode and translate the idea approximately into lisp, but have to rework it completely for python.

Therefore I conclude that while python does often look very similar to pseudocode written in a book, lisp is in a way also very similar to pseudocode because you can dream up very flexible code constructs just as you would if you were explaining a problem to someone with no fixed programming language.