Sunday, May 9, 2010 :: Tagged under: pablolife. ⏰ 2 minutes.

Hey! Thanks for reading! Just a reminder that I wrote this some years ago, and may have much more complicated feelings about this topic than I did when I wrote it. Happy to elaborate, feel free to reach out to me! 😄

You can talk all you want about 'practicality,' but one way in which I see functional languages will ALWAYS beat imperative is the built-in love of lists. I simply can't express my distaste for always writing:

import java.util.Collection;
import java.util.Iterator;

// crap elided

Iterator<String> iterator = myCollection.iterator();

while (iterator.hasNext()) {

over, say:

(map do-something-with-string my-collection)

But Paul! says you, Java gives you static typing! The Scheme example above doesn't, so it can get away with that kind of dynamic-language brevity! Well, so does Haskell:

map doSomethingWithString myCollection

and SML:


For fun, lets just see it in a smattering of other languages I've used. Ruby:

my_collection.each { |x| do_something_with_string x }


lists:foreach(fun do_something_with_string/1, MyCollection),

Common Lisp:

(mapcar #'do-something-with-string my-collection)

Naturally, this isn't even the whole picture. The example assumes you're iterating for side effects; if you needed the list with its elements transformed, that would be another 5-7 lines of Java. And the list can only exist because it was constructed to begin with, which if you did it in another class, requires 3-6 more import declarations there.

I know its trendy to hate on Java, and I've mentioned before that PL hating like this is unproductive. Still, we use and work with variable-sized lists all the time, and what functional designers figured out (long, long ago) is that it's quite nice to have them built-in.

Bleh, sorry. Android programming is fun, despite the Java.

I did say "imperative" above, not just Java. Kind of a misnomer, as CL and Ruby, above, provide one-line map and are arguably imperative. In that case, I let my biases shine through and used "imperative" interchangeably with "luddite." But let's never forget our buddy C++:

using namespace std;

list<string>::iterator iter;

for (iter = my_collection->begin(); iter != my_collection->end(); ++iter) {


Thanks for the read! Disagreed? Violent agreement!? Feel free to join my mailing list, drop me a line at , or leave a comment below! I'd love to hear from you 😄