From [the accepted answer][1] to "Why is Lisp useful?":

>  5. Wartiness. The real world is messy. Pragmatic coding winds up having to either use or invent messy constructs. Common Lisp has
> sufficient wartiness that it can get stuff done.

This thought has occurred to me, too. I'm currently developing an application whose backend I chose to write in Haskell, and whose frontend is in PHP. My experience has been that dealing with messy code in PHP is *much* easier than dealing with messy code in Haskell. However, it's my own code, and my PHP code probably isn't all that bad.

A simple example of "wartiness" is PHP's `==` (equality) operator. You know, the [type of equality][2] where `'' == 0` is true. Since I'm wary of `==`, I often choose to use PHP's `===` (strict equality) operator instead:

 $is_admin = ($gid === 24 || $gid === 25);

However, the above usage turned out to be wrong. The `$gid` value came from the database, and is still a string. This time, the strict equality operator bit me, and I would have saved myself a few minutes by simply saying:

 $is_admin = ($gid == 24 || $gid == 25);

Consider another interesting identity:

 php> var_dump('0012345' == '12345');
 bool(true)

What the heck?! `==` on two strings isn't even string comparison! However, consider if the user is given an ID card that says `0012345`, but the database ID is simply `12345`. Users may have trouble logging in to your application if you chose to use `===`. Sure, you'll get a bug report, and you'll be able to make your application correct rather than relying on this obscure feature. But it'll take more time. I'd rather spend that time outside. It's a really nice day.

By contrast, here's an example of wartiness that is *not* helpful in most cases:

 js> parseInt(031);
 25

What are some more concrete examples where "wartiness" helps you Get Things Done? Please explain why; don't just list features Haskell doesn't have.

Another way of putting it: what are some warty language features to be aware of, and how can we use them to save time?

 [1]: http://programmers.stackexchange.com/a/9358/3650
 [2]: http://stackoverflow.com/a/1998224/149391