Lisp macros feel like cheating

Common Lisp macros feel like cheating. I’ve reached chapter 9 of Practical Common Lisp, where the goal is to build a unit test framework, and you can see right away how the patterns are easily abstracted out with macros. It’s so easy it feels like cheating.

Getting a text representation of the test code to be able to point what when wrong, to show the piece of code failing, is supposed to be a hard task. Well, it is a hard task, sometimes impossible, in most programming languages. In Common Lisp it’s so trivial, it feels like cheating.

If you want to know what Lisp is about, read up to chapter 9 of PCL (Practical Common Lisp), at least. I used to tell people to at least read chapter 3, but it seems not to be enough, sadly, to impress the average programmer (either because they just don’t see it or chapter 3 is still too basic).

Comments at the original blog

Nubis Says:

Hey, good point. You know what also feels like cheating to me? The loop language.
I mean, from the 99 lisp problems:
Flatten a tree of lists:

(defun flatten (list)
  (loop for i in list if (listp i) append (flatten i) else collect i))

or, remove duplicated values from a list

(defun makeset (list)
  (loop for i in list unless (find i set) collect i into set finally (return set)))

At first it looks like cheating, but then i realized that the loop language is to lists what regular expressions are to strings, and it’s better than having a bunch of different people writing their loops and boilerplate in different ways.

best regards

September 3rd, 2007 at 4:30 e


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