On Fri, 11 Jan 2008 09:16:12 +0200, Lennart Augustsson
<[EMAIL PROTECTED]> wrote:
Thank you Duncan, you took the words out of my mouth. :)
On Jan 10, 2008 5:42 PM, Duncan Coutts <[EMAIL PROTECTED]>
wrote:
>
So let's imagine:
ones = 1 : ones
ones' = repeat 1
where repeat n = n : repeat n
So you're suggesting that:
ones == ones = True
but
ones' == ones' = _|_
Well if that were the case then it is distinguishing two equal values
and hence breaking referential transparency. We can fairly trivially
prove that ones and ones' are equal so == is not allowed to distinguish
them. Fortunately it is impossible to write == above, at least using
primitives within the language.
If one can prove ones == ones = True with some method, why that method
cannot be made to work on ones' ?
Are you thinking about repeat (f x) by any chance ?
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