OO (was: Why is tcl broken?)

Harvey J. Stein hjstein at bfr.co.il
Tue Jun 15 23:46:56 CEST 1999


wtanksle at dolphin.openprojects.net (William Tanksley) writes:

 > On Tue, 15 Jun 1999 01:54:53 GMT, Maxwell Sayles wrote:
 > >Robin Becker wrote:
 > 
 > >> postfix, prefix, infix etc etc are isosemantic
 > 
 > >for myself and the others who might not know... can we get an example of
 > >each?
 > >and i remember someone mentioned parenthesized vs non-parenthesized...
 > 
 > Infix (ML and Prolog):
 > 
 >   3 + (4 minus 10) == 1
 > (parenthesis are not optional)
 > 
 > Prefix (C, Lisp, Scheme):
 > 
 >   function(that(x(1)))
 > or:
 >   (do-this (do-that (x 1)))
 > (Parenthesis are not optional)
 > 
 > Postfix (Forth, Postscript):
 > 
 >   3 4 + SWAP MOD do-that
 >   rinse on   agitate  10 seconds   rinse off
 > (Parenthesis are not optional)
 > 
 > As a common thread, note that in none of the languages are parenthesis
 > optional.  In Postfix parenthesis are not optional because they have nno
 > meaning; in the other languages they're assigned arbitrary meaning.

This isn't a completely fair example.  Postfix can get away without
parentheses only when a) everything that's not a number is a function
and b) the arity (# of arguments) of each function is known and fixed.

Given such restrictions one can also drop the parentheses in prefix
notation.

Infix still requires parentheses even given the above restrictions.

-- 
Harvey J. Stein
Bloomberg LP
hjstein at bfr.co.il




More information about the Python-list mailing list