lazy comparison for equality ?
Wed, 24 Apr 2002 21:43:16 +0200
I'm a Haskell beginner and I have a problem.
Let's have a list which may be normal list
list1 = [1,2,3]
or a circular list
list2 = 1:2:list2
Now I'd like to have a function which tells me whether the
given list is circular or not. This doesn't work:
circ l = l l
circ2 l  = False
circ2 l (_:as) | l==as = True
| True = (circ2 l as)
It seems that comparison l==as really compares element by element thus
falling into an infinite loop. I would need to compare pointers instead of
Does anybody know how this could be done ?