\ system.v4 -- words about the dictionary as a whole: WORDS, FORGET, FENCE.
\
\ DECOMPOSITION.md 5.13 and 5.15.  Part of the compiler capsule; rests on
\ dict.v4, quit.v4 and forth.v4.
\
\ Constants the loader supplies:
\   FENCE   word address of the variable: FORGET will not remove an entry
\           that starts below the address it holds

header FENCE inline     : FENCE'  FENCE ;

\ ( -- )   the names in the dictionary, the newest first, a blank after
\ each, a new line whenever one has passed column 64.  Hidden entries -- a
\ definition under way -- are not shown.  (Q)+0 is the column.
header WORDS
: WORDS
  0 (Q) a! !
  LATEST
  L: if DONE
     dup -3 + a! @ 2 and if SHOW  drop jump NXT
     SHOW: drop
       dup -2 + a! @ 4*  COUNT 31 and        \ xt baddr u
       dup (Q) a! @ + 1 + !
       TYPE SPACE
       (Q) a! @ -64 + -if WRAP  drop jump NXT
       WRAP: drop  CR  0 (Q) a! !
     NXT: -1 + a! @  jump L
  DONE: drop  jump CR
header VLIST
: VLIST   jump WORDS

\ FORGET xxx   FORTH-79: remove xxx and every word defined after it.  The
\ space they took is free again.  A word that is not there is an error, and
\ so is one below FENCE, which is where the capsule's own words are (code
\ 10, "Protected word").
header FORGET
: FORGET
  32 WORD (LOOKUP) if MISSING
  dup -2 + a! @                              \ xt name
  dup FENCE a! @ inv + 1 + -if OK            \ name - fence
    drop drop drop  NODE-ERROR b! 10 !b ;
  OK: drop
  4* DP a! !                                 \ the space from its name on
  -1 + a! @ (LATEST) a! ! ;                  \ and the entry before it is the newest
  MISSING: drop  (UNKNOWN) drop ;