title:  Addition [of integers]

description:
 This is one of the most well-known Forth one-liners.
 In the short form, it looks like following:

 : + BEGIN DUP WHILE 2DUP AND 2* >R XOR R> REPEAT DROP ;

explanation:

> From: Wil Baden <neilbawd@earthlink.net>

: +                         ( x y -- x+y )
    BEGIN  DUP WHILE
        2DUP AND 2*  \  Calculate bit carries.
        >R XOR R>    \  Calculate bit sums.
    REPEAT DROP
;