Because we have redefined the left parenthesis, from this point on, inline comments must be done with a double left parenthesis.

: (( ( -- )  POSTPONE ( ; IMMEDIATE
: ( (( -- )  ['] DUMMY >BODY >P ; IMMEDIATE
PREVIOUS FORTH
\ ----- End of code -----

Defining KISS-commands

KISS +      KISS -       KISS *       KISS /

Indeed, that's all there is to it to make KISS-commands out of existing Forth words! From this point on, + - * and / act (almost) like they do in, e.g., BASIC. Or to put a finer point on it:

• A KISS-command uses the immediately following word as its argument: infix-notation, ex. 1.
• When a left parenthesis is found, all words up to the right parenthesis are arguments: prefix-notation, ex. 2.

Take care:

• Parentheses are Forth words and must be separated by at least one space from the preceding or following text.
• Precendence rules are not implemented (check out ex. 3, 4 and 5).

1)  BASE @ + 1 .         \ 11
2)  1 + ( BASE @ ) .     \ 11
3)  3 + 4 * 5 .          \ 35
4)  ( 3 + 4 ) * 5 .      \ 35
5)  3 + ( 4 * 5 ) .      \ 23

KISS-commands work inside definitions.

: DOZEN (( x -- x*12 ) * 12 ;