: (map) ( a n - a a')   cells over + swap ;
: map[   postpone (map)  postpone ?do postpone I postpone @ ; immediate
: ]map   1 cells postpone literal  postpone +loop ; immediate

create array 1000 cells allot   
: init  1000 0 DO I  array I cells + !  LOOP ;
init
: step  0  array 1000 map[ + ]map drop ;
: bench  100000 0 DO step LOOP ;
bench

\ Article: 127789 of comp.lang.forth
\ Path: tunews.univie.ac.at!aconews-feed.univie.ac.at!newsfeed.wu-wien.ac.at!newsfeed.utanet.at!feeder06.uucp-net.de!news.uucp.at!news.karotte.org!newsfeed00.sul.t-online.de!t-online.de!newsfeed.freenet.de!feeder.news-service.com!feeder2.cambrium.nl!feeder1.cambrium.nl!feed.tweaknews.nl!138.199.65.86.MISMATCH!sn-xt-ams-06!sn-xt-ams-04!sn-ams!sn-feed-ams-03!sn-post-ams-02!sn-post-sjc-01!supernews.com!news.supernews.com!not-for-mail
\ From: Andrew Haley <andrew29@littlepinkcloud.invalid>
\ Newsgroups: comp.lang.forth
\ Subject: Re: Factor, Postscript, and Forth: A case study
\ Date: Sat, 05 May 2007 10:39:10 -0000
\ Message-ID: <133onme7og5eq06@news.supernews.com>
\ References: <133m9nohdhdje47@news.supernews.com> <38823519183560@frunobulax.edu>
\ User-Agent: tin/1.4.4-20000803 ("Vet for the Insane") (UNIX) (Linux/2.6.18-1.2798.fc6 (x86_64))
\ X-Complaints-To: abuse@supernews.com
\ Lines: 16
\ Xref: tunews.univie.ac.at comp.lang.forth:127789
\ 
\ Marcel Hendrix <mhx@iae.nl> wrote:
\ > Andrew Haley <andrew29@littlepinkcloud.invalid> writes Re: Factor, Postscript, and Forth: A case study
\ > [..]
\ >> The classic Forth way to do this would be with compiling words, not by
\ >> passing an xt:
\ 
\ >> : (map) ( a n - a a')   cells over + swap ;
\ >> : map[   postpone (map)  postpone ?do ; immediate
\ > [..]
\ 
\ > I assume you meant   
\ >   : map[   postpone (map)  postpone ?do postpone I postpone @ ; immediate 
\ 
\ Sorry, yes.
\ 
\ Andrew.