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

On Fri, 27 Mar 2009, Jason Dusek wrote:

2009/03/27 John Lato :

...

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.