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Re: Josephus Circle problem

From Tristan Plumb <firth@trstn.net>
Newsgroups comp.lang.forth
Subject Re: Josephus Circle problem
Date 2013-12-26 14:37 +0000
Organization NewsGuy - Unlimited Usenet $19.95
Message-ID <slrnlbofou.6u6.st@tumtum.plumbweb.net> (permalink)
References <7x61qfuel8.fsf@ruckus.brouhaha.com> <l9cpi3$gt9$1@dont-email.me> <ccb911cb-e3e5-46e1-9bdb-4da9d16aef50@googlegroups.com> <383caaa9-5308-4d58-b118-eec96803840e@googlegroups.com> <l9h1q6$glb$1@dont-email.me>

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On 2013-12-26, Gerry Jackson <spam@qlikz.org> wrote:
> Or, to link up with the quotations discussion, and as long as your 
> stacks are big enough

I've been trying to explain my take on quotations, thank you!

>: josephus  [: dup 1 <> if dup 1- recurse 2 + swap mod 1+ then ;] 
> execute . ;
>
> usage:
> 40 josephus

On the one hand the above looks more like bad factoring:

: josephus dup 1 <> if dup 1- recurse 2 + swap mod 1+ then ;

usage:
40 josephus .

However! Combinators can do amazing things with quotations. Take nrec:
Given f(0) and a function for f(n-1), find f(n). (Like Joy's primrec.)

: nrec ( n F F0 -- Fn ) rot 1+ 1 do over i swap execute loop nip ;

Yielding:

: josephus [: swap 2 + swap mod 1+ ;] 1 nrec ;

Which is just as understandable as, but not quite so testable as:

: (josephus) swap 2 + swap mod 1+ ;
: josephus ' (josephus) 1 nrec ;

Tristan

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Thread

Josephus Circle problem Paul Rubin <no.email@nospam.invalid> - 2013-12-23 19:12 -0800
  Re: Josephus Circle problem "Rod Pemberton" <dont_use_email@xnohavenotit.cnm> - 2013-12-24 02:49 -0500
    Re: Josephus Circle problem Paul Rubin <no.email@nospam.invalid> - 2013-12-24 01:13 -0800
      Re: Josephus Circle problem mhx@iae.nl - 2013-12-24 02:17 -0800
        Re: Josephus Circle problem ForthFreak <forthfreak@gmail.com> - 2013-12-24 03:45 -0800
          Re: Josephus Circle problem Paul Rubin <no.email@nospam.invalid> - 2013-12-24 04:25 -0800
            Re: Josephus Circle problem ForthFreak <forthfreak@gmail.com> - 2013-12-24 04:25 -0800
              Re: Josephus Circle problem Paul Rubin <no.email@nospam.invalid> - 2013-12-24 04:52 -0800
            Re: Josephus Circle problem albert@spenarnc.xs4all.nl (Albert van der Horst) - 2013-12-24 14:57 +0000
            Re: Josephus Circle problem "Ed" <invalid@invalid.com> - 2013-12-25 20:15 +1100
          Re: Josephus Circle problem mhx@iae.nl - 2013-12-24 04:36 -0800
      Re: Josephus Circle problem "Rod Pemberton" <dont_use_email@xnohavenotit.cnm> - 2013-12-24 17:05 -0500
      Re: Josephus Circle problem "WJ" <w_a_x_man@yahoo.com> - 2014-03-10 07:11 +0000
    Re: Josephus Circle problem mhx@iae.nl - 2013-12-24 02:59 -0800
  Re: Josephus Circle problem ForthFreak <forthfreak@gmail.com> - 2013-12-24 01:53 -0800
    Re: Josephus Circle problem Paul Rubin <no.email@nospam.invalid> - 2013-12-24 04:06 -0800
      Re: Josephus Circle problem ForthFreak <forthfreak@gmail.com> - 2013-12-24 04:24 -0800
  Re: Josephus Circle problem ForthFreak <forthfreak@gmail.com> - 2013-12-24 04:30 -0800
    Re: Josephus Circle problem ForthFreak <forthfreak@gmail.com> - 2013-12-24 04:35 -0800
  Re: Josephus Circle problem ForthFreak <forthfreak@gmail.com> - 2013-12-24 05:01 -0800
    Re: Josephus Circle problem Paul Rubin <no.email@nospam.invalid> - 2013-12-24 05:34 -0800
      Re: Josephus Circle problem ForthFreak <forthfreak@gmail.com> - 2013-12-24 05:22 -0800
      Re: Josephus Circle problem "Elizabeth D. Rather" <erather@forth.com> - 2013-12-24 13:25 -1000
        Re: Josephus Circle problem "Ed" <invalid@invalid.com> - 2013-12-25 20:40 +1100
          Re: Josephus Circle problem "Elizabeth D. Rather" <erather@forth.com> - 2013-12-25 09:37 -1000
            Re: Josephus Circle problem ForthFreak <forthfreak@gmail.com> - 2013-12-26 03:19 -0800
              Re: Josephus Circle problem "Elizabeth D. Rather" <erather@forth.com> - 2013-12-26 12:01 -1000
            Re: Josephus Circle problem "Ed" <invalid@invalid.com> - 2013-12-27 12:33 +1100
              Re: Josephus Circle problem Elizabeth D Rather <erather@forth.com> - 2013-12-26 17:41 -1000
                Re: Josephus Circle problem "Ed" <invalid@invalid.com> - 2013-12-27 18:46 +1100
                Re: Josephus Circle problem Mark Wills <markrobertwills@yahoo.co.uk> - 2013-12-27 02:46 -0800
                Re: Josephus Circle problem albert@spenarnc.xs4all.nl (Albert van der Horst) - 2013-12-27 13:16 +0000
                Re: Josephus Circle problem mhx@iae.nl - 2013-12-27 05:27 -0800
                Re: Josephus Circle problem albert@spenarnc.xs4all.nl (Albert van der Horst) - 2013-12-27 14:15 +0000
                Re: Josephus Circle problem "Ed" <invalid@invalid.com> - 2013-12-29 21:56 +1100
                Re: Josephus Circle problem albert@spenarnc.xs4all.nl (Albert van der Horst) - 2013-12-29 12:37 +0000
                Re: Josephus Circle problem "Ed" <invalid@invalid.com> - 2013-12-30 00:47 +1100
                Re: Josephus Circle problem "Ed" <invalid@invalid.com> - 2013-12-29 14:08 +1100
              Re: Josephus Circle problem Mark Wills <markrobertwills@yahoo.co.uk> - 2013-12-27 02:35 -0800
                Re: Josephus Circle problem Mark Wills <markrobertwills@yahoo.co.uk> - 2013-12-27 02:43 -0800
                Re: Josephus Circle problem albert@spenarnc.xs4all.nl (Albert van der Horst) - 2013-12-27 19:00 +0000
    Re: Josephus Circle problem albert@spenarnc.xs4all.nl (Albert van der Horst) - 2013-12-24 15:59 +0000
  Re: Josephus Circle problem Gerry Jackson <spam@qlikz.org> - 2013-12-24 20:07 +0000
    Re: Josephus Circle problem albert@spenarnc.xs4all.nl (Albert van der Horst) - 2013-12-24 20:31 +0000
    Re: Josephus Circle problem mhx@iae.nl - 2013-12-25 04:38 -0800
      Re: Josephus Circle problem mhx@iae.nl - 2013-12-25 06:04 -0800
      Re: Josephus Circle problem mhx@iae.nl - 2013-12-25 06:06 -0800
        Re: Josephus Circle problem Paul Rubin <no.email@nospam.invalid> - 2013-12-25 23:08 -0800
          Re: Josephus Circle problem ForthFreak <forthfreak@gmail.com> - 2013-12-26 03:31 -0800
        Re: Josephus Circle problem Gerry Jackson <spam@qlikz.org> - 2013-12-26 10:52 +0000
          Re: Josephus Circle problem Tristan Plumb <firth@trstn.net> - 2013-12-26 14:37 +0000
            Re: Josephus Circle problem Paul Rubin <no.email@nospam.invalid> - 2013-12-26 07:12 -0800
          Re: Josephus Circle problem Gerry Jackson <spam@qlikz.org> - 2013-12-26 17:31 +0000
        Re: Josephus Circle problem Ron Aaron <rambamist@gmail.com> - 2013-12-26 21:39 +0200
    Re: Josephus Circle problem anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-12-26 17:33 +0000

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