qrczak@knm.org.pl (Marcin 'Qrczak' Kowalczyk) writes:

'negate' defined, as it's obviously meaningless for them. We can put 'fromInteger' in some class and 'negate' in its subclass, and make only the former instance for natural numbers.

Nitpick: not necessarily its subclass, either. We can probably imagine types where negate makes sense, but fromInteger does not, as well as vice versa. -kzm -- If I haven't seen further, it is by standing in the footprints of giants