18 Jan
2005
18 Jan
'05
5:03 p.m.
On 18 Jan 2005, at 21:45, Ulises Juarez Martinez wrote:
Who can I do an instance of Eq (Ocurrence -> Bool)? Is there another option to avoid the error?
In general, you can't define one. To define equality on functions you want to check the value on every possible input, and since Ocurrence is an infinite type, that can't be done in a finite time. In this specific case, you are dealing with indicator functions, which are isomorphic to (possibly infinite) Sets of Ocurrences. If you happen to know that they will always be finite (or, perhaps, always cofinite) you might solve the problem by using that representation. Jules