gforth-tutorial/10-local-variables.fth

\ Assignment: Write colon definitions for nip, tuck, negate,
\ and /mod in terms of other Forth words, and check if they
\ work (hint: test your tests on the originals first). Don't
\ let the `redefined'-Messages spook you, they are just
\ warnings.

: nip ( a b c -- a b ) swap drop ;
: tuck ( a b c -- a c b c ) swap over ;
: negate ( n -- -n ) -1 * ;
: /mod ( a b -- a modulo b, a div b) 2dup mod rot rot / ;

\ Assignment: Rewrite your definitions until now using locals.

: nip ( a b c -- a c ) { a b c } a b ;
: tuck ( a b c -- a c b c ) { a b c } a c b c ;
: negate ( n -- -n ) { n } n -1 * ;
: /mod ( a b -- a modulo b, a div b)
  { a b }
  a b a b
  mod rot rot / ;