[Haskell-cafe] Re: Use unsafePerformIO to catch Exception?

[Henning Thielemann]

On Fri, 27 Mar 2009, Jason Dusek wrote:

> 2009/03/27 John Lato <jwlato at gmail.com>:
>>
>> I could follow the rest of this, but I don't understand why
>> 'head' is necessary.  Couldn't you always replace it with a
>> case statement, with undefined on [] if necessary?
>
>  How would that be any different from head?

The psychological advantage is, that you had to do something with the case 
[] and programmers hopefully hesitate more to write 'error' than to write 
'head'. :-) Practically, if you have no better idea than writing 'error', 
you would write an error message that is more specific than "head: empty 
list", which makes debugging easier.