[racket] How to read procedure documentation?

Manfred Lotz wrote at 04/19/2013 02:18 PM:
>  From this I'm wondering why there are predicates when for example I
> would expect strings?
>    

The language you're seeing is mostly that of Racket *contracts*, even 
though the implementation might not be using the Racket contract 
software mechanism: 
http://docs.racket-lang.org/guide/contract-boundaries.html

It is not the prettiest or fastest way to communicate a synopsis for a 
bit of API, but you can quickly learn how to read it slowly.

Neil V.