Re: What about code blocks (not Forth blocks)?

From	Bernd Paysan <bernd.paysan@gmx.de>
Newsgroups	comp.lang.forth
Subject	Re: What about code blocks (not Forth blocks)?
Date	2014-03-12 20:21 +0100
Organization	1&1 Internet AG
Message-ID	<lfqc4l$hlm$1@online.de> (permalink)
References	(3 earlier) <59f8fc63-88ac-4cd0-a388-f7b487e6789c@googlegroups.com> <lfm7aq$9o5$1@dont-email.me> <lfmtqv$vkf$1@online.de> <be98314a-755e-4eda-a3c0-6302be0457f0@googlegroups.com> <489b5ae4-f169-4b23-9cb4-09d99c9d3f20@googlegroups.com>

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Julian Fondren wrote:

> If I want to pass arguments to a quotation, or maintain state on
> the stack, then my higher-order word has to manage this.  If I
> take the really obvious route and have all higher-worder words
> keep the data stack clean, then this is also more work for my
> higher-order words.  It strikes me that local variables would
> make things much easier.
> 
> For example,
> 
> \ boring, no problems here:
> : example1 ( -- )
> s" hello" [: cr emit ;] each-char ;
> 
> \ this burdens EACH-CHAR with keeping the data stack clean,
> \ when it would otherwise likely keep at least the XT on
> \ the stack.
> : example2 ( -- )
> 0 s" hello" [: cr emit 1+ ;] each-char
> cr ." Number of chars: " . ;
> 
> \ Hugh's ideal version.  EACH-CHAR doesn't have to do any
> \ extra work to keep the stack clear for the quotation, and
> \ the quotation also doesn't have to dig past the arguments
> \ provided by EACH-CHAR to reach EXAMPLE3's stack:
> : example3 ( -- )
> 0 { c }  s" hello" [: cr emit  1 +to c ;] each-char
> cr ." Number of chars: " c . ;

Thanks for actually formulating it out.  Yes, that's Hugh's problem (ok, the 
real problem of Hugh is something else... ;-).  And yes, you can see that 
using locals for this stuff makes it more ugly, even though you use +TO for 
incrementing c.  This stuff is not natural to Forth, nested functions are 
Algol-style.

: each-char ( .. addr u xt -- .. ) \ xt: ( .. char -- .. )
  { xt } bounds DO  I c@ xt execute  LOOP ;

can use a local variable without being ugly; here, there's actually a 
benefit from the local variable, because the return stack version looks 
ugly:

: each-char ( .. addr u xt -- .. ) \ xt: ( .. char -- .. )
  -rot bounds DO  i c@ swap dup >r execute r>  LOOP  drop ;

I've written several higher-order words, and always used local variables to 
keep the stack empty.  This is easy to do, and therefore the right way, 
because Forth's philosophy is "keep it simple".

In any case: quotations are not yet part of Forth200x, because nobody made 
an RfD.  They are a de-facto standard, as several Forth systems already 
implement them or have free (and pretty simple) implementations ready.  
Their usefulness is still somewhat debated.

-- 
Bernd Paysan
"If you want it done right, you have to do it yourself"
http://bernd-paysan.de/

Thread

What about code blocks (not Forth blocks)? Alexander Skobelev <al.skobelev@gmail.com> - 2013-12-17 23:56 -0800
  Re: What about code blocks (not Forth blocks)? mhx@iae.nl - 2013-12-18 01:14 -0800
    Re: What about code blocks (not Forth blocks)? Mark Wills <markrobertwills@yahoo.co.uk> - 2013-12-18 01:34 -0800
    Re: What about code blocks (not Forth blocks)? Alexander Skobelev <al.skobelev@gmail.com> - 2013-12-18 02:33 -0800
      Re: What about code blocks (not Forth blocks)? Coos Haak <chforth@hccnet.nl> - 2013-12-18 14:36 +0100
        Re: What about code blocks (not Forth blocks)? Alexander Skobelev <al.skobelev@gmail.com> - 2013-12-18 06:24 -0800
          Re: What about code blocks (not Forth blocks)? Coos Haak <chforth@hccnet.nl> - 2013-12-19 02:54 +0100
            Re: What about code blocks (not Forth blocks)? Alexander Skobelev <al.skobelev@gmail.com> - 2013-12-18 22:12 -0800
      Re: What about code blocks (not Forth blocks)? mhx@iae.nl - 2013-12-18 05:43 -0800
  Re: What about code blocks (not Forth blocks)? albert@spenarnc.xs4all.nl (Albert van der Horst) - 2013-12-18 11:21 +0000
    Re: What about code blocks (not Forth blocks)? Alexander Skobelev <al.skobelev@gmail.com> - 2013-12-18 04:31 -0800
      Re: What about code blocks (not Forth blocks)? Ilya Tarasov <ilya74.tarasov@gmail.com> - 2013-12-18 04:49 -0800
        Re: What about code blocks (not Forth blocks)? Alexander Skobelev <al.skobelev@gmail.com> - 2013-12-18 05:12 -0800
  Re: What about code blocks (not Forth blocks)? "Elizabeth D. Rather" <erather@forth.com> - 2013-12-18 08:26 -1000
    Re: What about code blocks (not Forth blocks)? Paul Rubin <no.email@nospam.invalid> - 2013-12-18 11:03 -0800
      Re: What about code blocks (not Forth blocks)? Alexander Skobelev <al.skobelev@gmail.com> - 2013-12-18 11:21 -0800
    Re: What about code blocks (not Forth blocks)? Alexander Skobelev <al.skobelev@gmail.com> - 2013-12-18 11:19 -0800
      Re: What about code blocks (not Forth blocks)? "Elizabeth D. Rather" <erather@forth.com> - 2013-12-18 10:08 -1000
        Re: What about code blocks (not Forth blocks)? Bernd Paysan <bernd.paysan@gmx.de> - 2013-12-18 21:58 +0100
          Re: What about code blocks (not Forth blocks)? "Ed" <invalid@invalid.com> - 2013-12-19 14:15 +1100
            Re: What about code blocks (not Forth blocks)? "Alex McDonald" <blog@rivadpm.com> - 2013-12-19 13:32 +0000
              Re: What about code blocks (not Forth blocks)? "Ed" <invalid@invalid.com> - 2013-12-20 21:07 +1100
                Re: What about code blocks (not Forth blocks)? "Alex McDonald" <blog@rivadpm.com> - 2013-12-20 12:35 +0000
                Re: What about code blocks (not Forth blocks)? "Alex McDonald" <blog@rivadpm.com> - 2013-12-20 13:02 +0000
                Re: What about code blocks (not Forth blocks)? "Ed" <invalid@invalid.com> - 2013-12-22 14:19 +1100
                Re: What about code blocks (not Forth blocks)? "Alex McDonald" <blog@rivadpm.com> - 2013-12-22 10:15 +0000
                Re: What about code blocks (not Forth blocks)? "Ed" <invalid@invalid.com> - 2013-12-24 12:30 +1100
                Re: What about code blocks (not Forth blocks)? albert@spenarnc.xs4all.nl (Albert van der Horst) - 2013-12-24 16:48 +0000
                Re: What about code blocks (not Forth blocks)? "Ed" <invalid@invalid.com> - 2013-12-28 11:08 +1100
                Re: What about code blocks (not Forth blocks)? albert@spenarnc.xs4all.nl (Albert van der Horst) - 2013-12-28 11:40 +0000
                Re: What about code blocks (not Forth blocks)? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-12-26 18:03 +0000
                Re: What about code blocks (not Forth blocks)? Paul Rubin <no.email@nospam.invalid> - 2013-12-26 10:34 -0800
                Re: What about code blocks (not Forth blocks)? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-12-27 15:53 +0000
                Re: What about code blocks (not Forth blocks)? Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2013-12-28 17:26 +0000
                Re: What about code blocks (not Forth blocks)? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-12-28 17:53 +0000
                Re: What about code blocks (not Forth blocks)? Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2013-12-28 18:21 +0000
                Re: What about code blocks (not Forth blocks)? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-12-29 14:49 +0000
                Re: What about code blocks (not Forth blocks)? Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2013-12-29 20:45 +0000
                Re: What about code blocks (not Forth blocks)? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-12-30 17:08 +0000
                Re: What about code blocks (not Forth blocks)? Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2013-12-30 20:00 +0000
                Re: What about code blocks (not Forth blocks)? albert@spenarnc.xs4all.nl (Albert van der Horst) - 2013-12-28 18:04 +0000
                Re: What about code blocks (not Forth blocks)? Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2013-12-28 18:47 +0000
                Re: What about code blocks (not Forth blocks)? Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2013-12-28 19:12 +0000
                Re: What about code blocks (not Forth blocks)? "Ed" <invalid@invalid.com> - 2013-12-28 11:09 +1100
                Re: What about code blocks (not Forth blocks)? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-12-28 13:45 +0000
          Re: What about code blocks (not Forth blocks)? Elizabeth D Rather <erather@forth.com> - 2013-12-18 19:04 -1000
            Re: What about code blocks (not Forth blocks)? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-12-19 09:25 +0000
            Re: What about code blocks (not Forth blocks)? Paul Rubin <no.email@nospam.invalid> - 2013-12-19 05:00 -0800
        Re: What about code blocks (not Forth blocks)? Alexander Skobelev <al.skobelev@gmail.com> - 2013-12-18 23:41 -0800
        Re: What about code blocks (not Forth blocks)? Alexander Skobelev <al.skobelev@gmail.com> - 2013-12-19 01:00 -0800
        Re: What about code blocks (not Forth blocks)? Alexander Skobelev <al.skobelev@gmail.com> - 2013-12-19 02:47 -0800
          Re: What about code blocks (not Forth blocks)? Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2013-12-19 11:23 +0000
            Re: What about code blocks (not Forth blocks)? Alexander Skobelev <al.skobelev@gmail.com> - 2013-12-19 03:52 -0800
  Re: What about code blocks (not Forth blocks)? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-12-19 15:58 +0000
    Re: What about code blocks (not Forth blocks)? Paul Rubin <no.email@nospam.invalid> - 2013-12-19 10:05 -0800
      Re: What about code blocks (not Forth blocks)? "Alex McDonald" <blog@rivadpm.com> - 2013-12-19 20:07 +0000
        Re: What about code blocks (not Forth blocks)? Paul Rubin <no.email@nospam.invalid> - 2013-12-19 12:33 -0800
          Re: What about code blocks (not Forth blocks)? "Alex McDonald" <blog@rivadpm.com> - 2013-12-19 20:33 +0000
            Re: What about code blocks (not Forth blocks)? albert@spenarnc.xs4all.nl (Albert van der Horst) - 2013-12-19 20:52 +0000
            Re: What about code blocks (not Forth blocks)? Paul Rubin <no.email@nospam.invalid> - 2013-12-19 18:52 -0800
          Re: What about code blocks (not Forth blocks)? Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-12-28 12:52 -0600
            Re: What about code blocks (not Forth blocks)? Paul Rubin <no.email@nospam.invalid> - 2013-12-28 11:47 -0800
              Re: What about code blocks (not Forth blocks)? Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-12-29 07:39 -0600
                Re: What about code blocks (not Forth blocks)? Paul Rubin <no.email@nospam.invalid> - 2013-12-29 08:11 -0800
            Re: What about code blocks (not Forth blocks)? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-12-29 15:25 +0000
              Re: What about code blocks (not Forth blocks)? Paul Rubin <no.email@nospam.invalid> - 2013-12-29 08:15 -0800
                Re: What about code blocks (not Forth blocks)? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-12-29 16:03 +0000
                Re: What about code blocks (not Forth blocks)? Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2013-12-29 20:54 +0000
                Re: What about code blocks (not Forth blocks)? mhx@iae.nl - 2013-12-29 13:38 -0800
                Re: What about code blocks (not Forth blocks)? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-12-30 17:04 +0000
                Re: What about code blocks (not Forth blocks)? Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2013-12-30 20:05 +0000
                Re: What about code blocks (not Forth blocks)? Paul Rubin <no.email@nospam.invalid> - 2013-12-30 16:49 -0800
                Re: What about code blocks (not Forth blocks)? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2014-01-02 17:27 +0000
              Re: What about code blocks (not Forth blocks)? Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-12-29 16:40 -0600
                Re: What about code blocks (not Forth blocks)? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-12-30 16:51 +0000
                Re: What about code blocks (not Forth blocks)? Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-12-30 11:15 -0600
                Re: What about code blocks (not Forth blocks)? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-12-30 17:37 +0000
                Re: What about code blocks (not Forth blocks)? Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-12-30 12:07 -0600
        Re: What about code blocks (not Forth blocks)? "Alex McDonald" <blog@rivadpm.com> - 2013-12-20 13:50 +0000
      Re: What about code blocks (not Forth blocks)? hughaguilar96@yahoo.com - 2013-12-19 21:49 -0800
        Re: What about code blocks (not Forth blocks)? "Alex McDonald" <blog@rivadpm.com> - 2013-12-20 08:56 +0000
          Re: What about code blocks (not Forth blocks)? hughaguilar96@yahoo.com - 2014-04-03 19:13 -0700
        Re: What about code blocks (not Forth blocks)? "WJ" <w_a_x_man@yahoo.com> - 2014-03-11 05:35 +0000
          Re: What about code blocks (not Forth blocks)? Bernd Paysan <bernd.paysan@gmx.de> - 2014-03-11 12:59 +0100
            Re: What about code blocks (not Forth blocks)? hughaguilar96@yahoo.com - 2014-03-11 23:44 -0700
              Re: What about code blocks (not Forth blocks)? Julian Fondren <ayrnieu@gmail.com> - 2014-03-12 11:48 -0700
                Re: What about code blocks (not Forth blocks)? Bernd Paysan <bernd.paysan@gmx.de> - 2014-03-12 20:21 +0100
                Re: What about code blocks (not Forth blocks)? hughaguilar96@yahoo.com - 2014-03-12 23:35 -0700
                Re: What about code blocks (not Forth blocks)? "Alex McDonald" <blog@rivadpm.com> - 2014-03-14 14:25 +0000
                Re: What about code blocks (not Forth blocks)? Bernd Paysan <bernd.paysan@gmx.de> - 2014-03-14 16:36 +0100
                Re: What about code blocks (not Forth blocks)? mhx@iae.nl - 2014-03-14 11:27 -0700
                Re: What about code blocks (not Forth blocks)? hughaguilar96@yahoo.com - 2014-03-16 17:38 -0700
                Re: What about code blocks (not Forth blocks)? "Rod Pemberton" <dont_use_email@xnothavet.cqm> - 2014-03-17 03:35 -0400
                Re: What about code blocks (not Forth blocks)? Paul Rubin <no.email@nospam.invalid> - 2014-03-17 20:36 -0700
                Re: What about code blocks (not Forth blocks)? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2014-03-18 13:13 +0000
                Re: What about code blocks (not Forth blocks)? albert@spenarnc.xs4all.nl (Albert van der Horst) - 2014-03-18 14:28 +0000
                Re: What about code blocks (not Forth blocks)? Paul Rubin <no.email@nospam.invalid> - 2014-03-18 10:10 -0700
                Re: What about code blocks (not Forth blocks)? Paul Rubin <no.email@nospam.invalid> - 2014-03-25 12:54 -0700
                Re: What about code blocks (not Forth blocks)? hughaguilar96@yahoo.com - 2014-03-25 23:09 -0700
                Re: What about code blocks (not Forth blocks)? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2014-03-26 13:49 +0000
                Re: What about code blocks (not Forth blocks)? Bernd Paysan <bernd.paysan@gmx.de> - 2014-03-26 22:07 +0100
                Re: What about code blocks (not Forth blocks)? hughaguilar96@yahoo.com - 2014-03-20 22:11 -0700
                Re: What about code blocks (not Forth blocks)? hughaguilar96@yahoo.com - 2014-03-28 22:18 -0700
                Re: What about code blocks (not Forth blocks)? "Alex McDonald" <blog@rivadpm.com> - 2014-03-29 10:57 +0000
                Re: What about code blocks (not Forth blocks)? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2014-03-13 16:42 +0000
          Re: What about code blocks (not Forth blocks)? albert@spenarnc.xs4all.nl (Albert van der Horst) - 2014-03-11 12:51 +0000
            Re: What about code blocks (not Forth blocks)? "Alex McDonald" <blog@rivadpm.com> - 2014-03-11 14:54 +0000
    Re: What about code blocks (not Forth blocks)? Alexander Skobelev <al.skobelev@gmail.com> - 2013-12-19 21:36 -0800
      Re: What about code blocks (not Forth blocks)? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-12-20 16:56 +0000
    Re: What about code blocks (not Forth blocks)? Alexander Skobelev <al.skobelev@gmail.com> - 2013-12-19 23:24 -0800
      Re: What about code blocks (not Forth blocks)? mhx@iae.nl - 2013-12-20 02:05 -0800
      Re: What about code blocks (not Forth blocks)? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-12-20 12:41 +0000
        Re: What about code blocks (not Forth blocks)? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-12-20 17:46 +0000
          Re: What about code blocks (not Forth blocks)? Alexander Skobelev <al.skobelev@gmail.com> - 2013-12-21 08:11 -0800
            Re: What about code blocks (not Forth blocks)? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-12-23 10:07 +0000
              Re: What about code blocks (not Forth blocks)? Bernd Paysan <bernd.paysan@gmx.de> - 2013-12-23 19:31 +0100
                Re: What about code blocks (not Forth blocks)? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-12-26 17:45 +0000

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