[Haskell-cafe] Wikipedia on first-class object
Wolfgang Jeltsch
g9ks157k at acme.softbase.org
Thu Dec 27 11:19:47 EST 2007
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
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