[Haskell-cafe] Re: Wikipedia on first-class object

Yitzchak Gale gale at sefer.org
Thu Dec 27 16:58:16 EST 2007

Wolfgang Jeltsch wrote:
>> If x doesn't equal y, x == y is False, but if x
>> equals y, x == y might be True or undefined.

apfelmus wrote:
> x == y  may be _|_ for the False case, too, depending on its
> implementation (like first comparing all list elements on even indices
> and then comparing all list elements on odd indices). But the standard
> == for lists has indeed the stated property.

[undefined] doesn't equal [1] but  [undefined]==[1] is _|_, not False.


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