[Haskell-cafe] Wikipedia on first-class object

[Wolfgang Jeltsch]

Am Donnerstag, 27. Dezember 2007 16:34 schrieb Cristian Baboi:
> I'll have to trust you, because I cannot test it.
>
> let x=(1:x); y=(1:y) in x==y .
>
> I also cannot test this:
>
> let x=(1:x); y=1:1:y in x==y

In these examples, x and y denote the same value but the result of x == y is 
_|_ (undefined) in both cases.  So (==) is not really equality in Haskell but 
a kind of weak equality: If x doesn’t equal y, x == y is False, but if x 
equals y, x == y might be True or undefined.

Best wishes,
Wolfgang