getting 'full' names of functions?

Hello,

before I reinvent the wheel I'd like to know whether there's a shortcut for getting the 'full' name (incl. argtypes) of
thefunctions within a database in order to REVOKE priviliges on them given to certain users. 
I don't see anything in the docs:
http://www.postgresql.org/docs/8.3/interactive/functions-info.html#FUNCTIONS-INFO-CATALOG-TABLE

Obviously you can't just use the specific_name from information_schema.routine_privileges for this.

Any help is appreciated.

Thank you very much,

Peter
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