Why are Clojure's multimethods better than 'if' or 'case' statements
case, clojure, multimethod, polymorphism, switch-statement
Solution
The difference between multimethods and a big if-statement is that you need to modify the function that contains the case-statement to add cases to the if-statement. You can add a new method without touching the previously existing methods.
So if you define a multimethod inside your library and you want your users to be able to extend it for their own data types, that's no problem. If you had used an if-statement instead, it would be a big problem.
Problem
I've spent some time, trying to understand Clojure multimethods. The main "pro" multimethod argument, as far as I understand, is their flexibility, however, I'm confused with the argumentation of why multimethods are better than a simple if or case statement. Could someone, please, explain, where is the line between polymorphism and an overglorified case statement drawn? EDIT: I should have been clearer in the question, that I'm more interested in comparison with the 'if' statement. Thanks a lot for the answers!