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

Wolfgang Jeltsch wrote:

Am Freitag, 28. Dezember 2007 07:49 schrieben Sie:

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On Thu, 27 Dec 2007 18:19:47 +0200, Wolfgang Jeltsch wrote:

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Am Donnerstag, 27. Dezember 2007 16:34 schrieb Cristian Baboi:

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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.

Thank you.

I can only notice that y always has an even number of 1, which is not the case for x :-)

Both have an infinite number of 1. Why do you say “always”? It seems that you think of x and y as “variables” whose values change over time. This is not the case. They both have a single value for all time: the infinite list consisting only of 1.

Does that then mean that [1] = [1,1] ?