Forth common practice

From Rosetta Code

The Forth language has a standardized vocabulary, but many words have become common practice since that 1994 standard.

 1 cells constant  cell
-1 cells constant -cell
: cell-  -cell + ;
: -rot ( a b c -- c a b ) rot rot ;
: bounds ( addr len -- limit addr ) over + swap ;  \ convert string/array to DO-LOOP limits

DEFER-IS for late-bound, revectorable, and forward-referenced words:

: noop ( -- ) ;
: defer  create ( "name" -- ) ['] noop ,   does> ( -- ) @ execute ;
: is ( xt "name" -- ) ' >body ! ;

defer lessthan
' < is lessthan
2 3 lessthan .  \ -1 (true)

Alternate local variable syntax using curly braces, designed to look like a regular stack comment:

: muldiv { a b -- a*b a/b }     \ all stuff after "--" is ignored
  a b *  a b / ;

Some counted string utilities:

: c+! ( n caddr -- ) dup >r [email protected] + r> c! ;
: append ( src len dest -- ) 2dup 2>r  count + swap move  2r> c+! ;
: place ( src len dest -- ) 2dup 2>r  1+ swap move  2r> c! ;
: scan ( str len char -- str' len' ) >r begin dup while over [email protected] [email protected] <> while 1 /string repeat then r> drop ;
: skip ( str len char -- str' len' ) >r begin dup while over [email protected] [email protected] =  while 1 /string repeat then r> drop ;
: split ( str len char -- str1 len1 str2 len2 ) >r 2dup r> scan 2swap 2 pick - ;