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From: sjack@dontemail.me (sjack)
Newsgroups: comp.lang.forth
Subject: Re: Back & Forth - Co-routines
Date: Sat, 22 Mar 2025 15:51:18 -0000 (UTC)
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Ruvim <ruvim.pinka@gmail.com> wrote:

> An artificial example:

While wondering down roads less taken, I took a path where
bacForth CUT: and -CUT were used in lieu of CATCH THROW . 


( ENTER is the same as ';:' )
: LOCAL ( x adr -- )
    r> -rot dup @ over 2>r ! ENTER 2r> ! ;

\ prefixed '-' to indicate this word does a cut
: -idiv ( n1 n2\0 -- n3 |  n1 0 -- true )
  dup if / 
    else 2drop true -CUT
    then
;

: ?idiv ( n1 n2 -- n1/n2 false | <nothing> )
  CUT: -idiv ." Valid: " false       
;

42 variable a
42 variable b

: ?/ ( u1 u2 -- u1/u2 )
  a local b local
  b @ a @ ?idiv 
  if ." Bogus! " 666 then .
;

i. 100 5 ?/ --> Valid: 20 
i. a ? b ? --> 42 42 
i. 100 0 ?/ --> Bogus! 666 
i. a ? b ? --> 42 42 

forget ?/

: ?/ ( u1 u2 -- u1/u2 )
  a local b local
  b @ a @ ' ?idiv ENTER  
  if ." Bogus! " 666 then .
;

i. 100 5 ?/ --> Valid: 20 
i. a ? b ? --> 42 42 
i. 100 0 ?/ --> Bogus! 666 
i. a ? b ? --> 42 42 

forget ?/

: ?/ ( u1 u2 -- u1/u2 )
  a local b local
  b @ a @ (: cut: -idiv ." Valid: " false ;) ENTER 
  if ." Bogus! " 666 then .
;

i. 100 5 ?/ --> Valid: 20 
i. a ? b ? --> 42 42 
i. 100 0 ?/ --> Bogus! 666 
i. a ? b ? --> 42 42 

+echo
-fin-