I thought about it and came to the conclusion that most of the time, if I'm given a totally wrong type of input (scalar when I expected a hashref, or something similar), it is a rare case that the program can recover gracefully.

Even if you could recover gracefully from wrong input, it's probably a bad idea. If you get wrong input, then somewhere along the line someone screwed up, and about the worst thing you can do is hide the problem (or at least pass it on to another chunk of code further away from the original) and make it harder to debug. That sort of false "defensive programming" isn't just a waste of time, it's actively harmful.

In general, I like to write code that fails -- gracefully, mind you, not locking up the machine or any such -- as soon as possible on bad assumptions. Makes it easier to find bugs.

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F o x t r o t U n i f o r m
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The hell with paco, vote for Erudil!