Frank Dellaert asks:
> test (Instance a1 _) (Instance a2 _) = (a1==a2)
>
> will this be implemented efficiently ? I.e. will it check first whether the >
>pointers happen to be the same, and only then do a full Eq comparison ?
No, otherwise you might also expect that the following test' function:
test' :: String -> Bool
test' s = (s==s)
always returns True, without considering its actual argument s. But this
is not the way of it, (==) evaluates the two strings to be compared as
far as necessary for this comparison. For example:
test' "abc" = True
but:
test' undefined = undefined
If you really need something like pointer equality, you might want to
consider the stable names of:
@inproceedings{ jones99stretching,
author = "Simon L. Peyton Jones and Simon Marlow and Conal Elliott",
title = "Stretching the Storage Manager: Weak Pointers and Stable
Names in Haskell",
booktitle = "Implementation of Functional Languages",
pages = "37-58",
year = "1999",
url = "citeseer.nj.nec.com/jones99stretching.html" }
--
Janis Voigtlaender
http://wwwtcs.inf.tu-dresden.de/~voigt/
mailto:[EMAIL PROTECTED]
_______________________________________________
Haskell mailing list
[EMAIL PROTECTED]
http://www.haskell.org/mailman/listinfo/haskell
