2007/8/15, Alexteslin
I am really sorry, but i still can't define the function. The chapter the exercise is in precedes algebraic types or Maybe a types. And is seems that must being easy to define.
If you don't have Maybe, you still have it's older brother, namely lists (as strongly hinted by Jon Fairbairn).
so you need an f so that c `f` x is c (for any c and x) and yet (b `f` c) is c for any c and b -- this is impossible (or I'm asleep).
Well, it isn't "impossible" but quite hard (and not even standard H98 if I'm not mistaken) and obviously not in the range of the possibilities here. Still you could "approximate" it, and in fact I believe the [Char] -> Char requirement is hinting at such a (arguably and IMO ugly) solution. For example you could assume there would be no "NUL" character in a string ([Char] is a synonym for String, or vice-versa), and then get a simple myLast for String in this restrictive case (and looking exactly like Alexteslin sample). -- Jedaï