why the parentheses after typenames?

[Kostis Sagonas]

Matthias Lang asked:
 > 
 > something I've wondered a few times. In the documentation, types are
 > often denoted by putting parentheses after names, e.g.
 > 
 >    len(String) -> Length
 > 
 >       Types:
 >             String = string()
 >             Length = integer()
 > 
 > what's behind this? Is there an explanation somewhere?

I am assuming this is so that the type integer() is distinguishable
from the atom 'integer'.

Kostis