overloading operators for I/O

[Manfred Nowak]

Michiel wrote

> An operator should
> be intuitive (readable) and easy to use. A prefix pretty much
> removes that advantage, and I would rather use functions. (By the
> way, I think the operator-symbols should at least be on a standard
> keyboard.) 
> 
> But ->, <-, postfix !, !in, etc. would be good.

New operators are not intuitiv either, because one has to learn their 
priorities---or one will end up with fully parenthesed expressions.

Whether a prefix or a postfix and what characters will be choosen are 
of minor importance. I referred to the degree sign, because it is on 
the german standard keyboard and reminds at the often used middle 
circle in abstract algebras.

-manfred