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From: UNBCIC@BRFAPESP.BITNET
Newsgroups: comp.lang.forth
Subject: What makes Forth Forth
Message-ID: <9012092322.AA04013@ucbvax.Berkeley.EDU>
Date: 8 Dec 90 15:47:00 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Reply-To: UNBCIC%BRFAPESP.BITNET@SCFVM.GSFC.NASA.GOV
Organization: The Internet
Lines: 37

> >                               I *DO* see an objection -- and I
> >regard a strength of Forth as the ability to add new objects with
> >first class status. This ability comes from the fact that the Forth
> >programmer has access to the language at the level at which primary
> >objects are introduced...

> Well, what do you say to the C++/Ada/Smalltalk people then.  They can
> certainly do that too.

Let's talk about C++ and Ada first. I know almost nothing about the ++ part of
C++ and don't remember well Ada, but can you do:

VOCABULARY COMPLEX COMPLEX DEFINITIONS
: VARIABLE CREATE 2 CELLS ALLOT ;
: + [ FORTH ] ROT + ROT ROT + SWAP ;
: - [ FORTH ] ROT - ROT ROT - SWAP ;
: SWAP 2SWAP ;
: ! [ FORTH ] ROT OVER ! 2+ ! ;
: @ [ FORTH ] DUP @ SWAP 2+ @ ;
: . [ FORTH ] . ?DUP IF 0> IF ." +" THEN . ." i" THEN ;

FORTH DEFINITIONS

COMPLEX
VARIABLE A VARIABLE B VARIABLE C VARIABLE D
2 3 A !
5 1 B !
A @ B @ + C !
A @ B @ SWAP - D !
C @ . CR D @ .

in Ada or C++? You can do this in Smaltalk, but there are other things you
can't redefine in Smaltalk: blocks and arrays delimiters, sintax... In Forth
you can redefine anything.


                              (8-DCS)