16 Mar
2009
16 Mar
'09
10:58 a.m.
Am Samstag, 14. März 2009 23:33 schrieben Sie:
On Fri, 13 Mar 2009, Wolfgang Jeltsch wrote:
Class instances should satisfy certain laws. (Although these laws are often not stated explicitely, they are assumed to hold by users of the class and they should hold to make the instance sensible.) In the case of Num, I would expect num + negate num to equal num.
"equal zero" ?
Exactly. Best wishes, Wolfgang