Re: Implementing lisp in Forth. Chapter 4.

From	Paul Rubin <no.email@nospam.invalid>
Newsgroups	comp.lang.forth
Subject	Re: Implementing lisp in Forth. Chapter 4.
Date	2016-09-04 21:03 -0700
Organization	A noiseless patient Spider
Message-ID	<87bn03ngbt.fsf@jester.gateway.pace.com> (permalink)
References	<nq1ojd$rvh$1@cherry.spenarnc.xs4all.nl> <87twdznhhz.fsf@jester.gateway.pace.com> <nqbhus$4fp$1@cherry.spenarnc.xs4all.nl> <87fupfo6xl.fsf@jester.gateway.pace.com> <nqihtb$vns$1@cherry.spenarnc.xs4all.nl>

Show all headers | View raw

albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) writes:
>>  http://www.complang.tuwien.ac.at/forth/garbage-collection.zip
> The constraints that package imposes interferes with the non-existing
> constraints I will impose on a yet non-existent lisp.

I'd be interested to know what your objections are.  The technique that
package uses works very well and its C counterpart is used in many
real-world systems.

> I tell you what I'll do. I just ALLOCATE away in my 16 Gbyte space.
> If I know I can FREE I'll do it. Then I'll add GC as an afterthought.

Well, that's a start, though if you were doing a serious implementation
then a lot of the implementation details would be enmeshed in the gc
strategy so you'd want to think it all through from the beginning.

> the fib procedure remains there in all eternity and there is nothing
> to collect. I can do (fib 10) any time I please.  Or will there be
> anonymous memory places and are the boxes they are in such as
> (a,b,i,n) collectable?

It depends on your scheme's implementation details, the number
representation, etc.  But if they are fixnums and you have a compiler
that looks for such chances, that function can avoid consing.  A simple
implementation would just cons everything.  CPython works like that (it
caches 100 or so small integers and conses/gc's the rest) and tons of
people use it.  It's not as bad as it sounds.

> 354224848179261915075 does that leave garbage in your run of the mill
> scheme?

Yes, bignums are usually heap-allocated so if you create them as
intermediate results, they will leave garbage.

> In the procedure fib can I optimise the fib into machine code with
> (optimise fib)
> that optimises the underlying Forth code, without getting on
> someones toes?

In principle that could be ok.  You could look at Chicken Scheme, which
compiles Scheme to C if I remember properly.

> Obviously that may leave some garbage that may be harder to collect.

I don't think you should worry about optimizing this, especially for
your first implementation.  Just spew garbage wherever it's convenient
and let the GC take care of it.

> No it isn't, not in the Forth philosophy. The reader is the glue and
> Lisp doesn't exist, it is just turtles all the way down.

But I thought the idea of implementing Lisp was so you could program
with the Lisp philosophy, which is much different from the Forth
philosophy.  Forth is like building a brick outhouse, carefully
cementing each brick in place before moving to the next, getting
something compact and solid.  Lisp is more like dancing in the air.  You
can create a palace of data with a wave of your hand, use it for
something, then fly away from it, leaving the GC to reclaim the building
materials for you to use in your next adventure.

> (It may well be that Lisp doesn't exist in the Lisp philosophy,
> just cdr's all the way down to the atom's. Dunno yet.)

Lisp very much exists in the traditional Lisp philosophy (you can build
up programs and eval them), even though this isn't supported in Scheme.

> It is not the gain, it is the loss. I loose an interpreter for Backus
> Naur forms. Less is more.

There's no BNF in a usual Lisp reader, but rather just a simple
recursive procedure that recognizes a few special characters and
otherwise acts like a Forth parser.  But you then have a tree to
manipulate, maybe for macro expansion or other purposes.  It's easier to
handle that in Lisp than in Forth.

> I just read the description of Guile. That is a Scheme dialect and
> Scheme is supposed to be simple. I can't detect the simplicity in it
> (not from the info file). It kind of deters me.  I see that guile
> binary is 3K, that seems okay, but it calls horrific c-libraries like
> the infamous readline, maybe even malloc.

Guile is quite large and complex these days, maybe to compete with
higher end Javascript implementations like v8.  That 3k binary is
certainly a dynamic loader client that pulls in other libraries.  It
looks like libguile-2.0.so.22 on my system is about 1.6MB and it also
pulls in a lot of other code.

You might look at this old (2.0) version of SIOD if you want to see a
minimal Scheme:

http://www.cs.cmu.edu/afs/cs/project/ai-repository/ai/lang/scheme/impl/siod/siod_20.tgz

This version is nice because it has two different gc's (mark-sweep and
copying) where you choose which one you want with a command line option.
Each gc is just a few dozen LOC.  Earlier versions only had the copying
GC.  Later versions became bigger and more complicated, maybe more
useful for practical purposes, but less easy to study.

SIOD stands for Scheme In One Day because the original version was
supposedly written in under 24 hours.  It's around 1 KLOC of C.

Thread

Implementing lisp in Forth. Chapter 4. albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-08-29 18:41 +0200
  Re: Implementing lisp in Forth. Chapter 4. Paul Rubin <no.email@nospam.invalid> - 2016-08-29 09:39 -0700
    Re: Implementing lisp in Forth. Chapter 4. albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-08-30 10:49 +0200
  Re: Implementing lisp in Forth. Chapter 4. Paul Rubin <no.email@nospam.invalid> - 2016-08-29 09:46 -0700
    Re: Implementing lisp in Forth. Chapter 4. albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-08-30 11:07 +0200
      Re: Implementing lisp in Forth. Chapter 4. Rod Pemberton <NoHaveNotOne@zxdehrnyya.cam> - 2016-08-30 08:00 -0400
        Re: Implementing lisp in Forth. Chapter 4. albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-09-02 12:34 +0200
      Re: Implementing lisp in Forth. Chapter 4. Paul Rubin <no.email@nospam.invalid> - 2016-08-31 14:23 -0700
        Re: Implementing lisp in Forth. Chapter 4. albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-09-01 02:15 +0200
          Re: Implementing lisp in Forth. Chapter 4. Paul Rubin <no.email@nospam.invalid> - 2016-09-01 19:49 -0700
            Re: Implementing lisp in Forth. Chapter 4. albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-09-02 11:49 +0200
              Re: Implementing lisp in Forth. Chapter 4. Paul Rubin <no.email@nospam.invalid> - 2016-09-04 11:28 -0700
                Re: Implementing lisp in Forth. Chapter 4. albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-09-05 03:31 +0200
                Re: Implementing lisp in Forth. Chapter 4. Paul Rubin <no.email@nospam.invalid> - 2016-09-04 21:03 -0700
                Re: Implementing lisp in Forth. Chapter 4. Spiros Bousbouras <spibou@gmail.com> - 2016-09-05 07:47 +0000
                Re: Implementing lisp in Forth. Chapter 4. albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-09-05 12:05 +0200
                Re: Implementing lisp in Forth. Chapter 4. Paul Rubin <no.email@nospam.invalid> - 2016-09-05 12:04 -0700
                Re: Implementing lisp in Forth. Chapter 4. albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-09-06 11:48 +0200
                Re: Implementing lisp in Forth. Chapter 4. Spiros Bousbouras <spibou@gmail.com> - 2016-09-06 15:32 +0000
                Re: Implementing lisp in Forth. Chapter 4. albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-09-06 21:27 +0200
                Re: Implementing lisp in Forth. Chapter 4. anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-09-06 19:50 +0000
                Re: Implementing lisp in Forth. Chapter 4. Stefan Monnier <monnier@iro.umontreal.ca> - 2016-09-08 12:15 -0400
                Re: Implementing lisp in Forth. Chapter 4. albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-09-08 20:09 +0200
                Re: Implementing lisp in Forth. Chapter 4. Paul Rubin <no.email@nospam.invalid> - 2016-09-08 12:34 -0700
                Re: Implementing lisp in Forth. Chapter 4. anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-09-12 10:17 +0000
                Re: Implementing lisp in Forth. Chapter 4. Stefan Monnier <monnier@iro.umontreal.ca> - 2016-09-12 11:50 -0400
                Re: Implementing lisp in Forth. Chapter 4. anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-09-12 16:48 +0000
                Re: Implementing lisp in Forth. Chapter 4. Stefan Monnier <monnier@iro.umontreal.ca> - 2016-09-12 13:41 -0400
                Re: Implementing lisp in Forth. Chapter 4. Paul Rubin <no.email@nospam.invalid> - 2016-09-06 22:03 -0700
                Re: Implementing lisp in Forth. Chapter 4. George Neuner <gneuner2@comcast.net> - 2016-09-08 16:50 -0400
                Re: Implementing lisp in Forth. Chapter 4. Paul Rubin <no.email@nospam.invalid> - 2016-09-08 16:34 -0700
                Re: Implementing lisp in Forth. Chapter 4. George Neuner <gneuner2@comcast.net> - 2016-09-09 00:12 -0400
                Re: Implementing lisp in Forth. Chapter 4. Paul Rubin <no.email@nospam.invalid> - 2016-09-08 22:22 -0700
                Re: Implementing lisp in Forth. Chapter 4. Lars Brinkhoff <lars.spam@nocrew.org> - 2016-09-27 08:51 +0200
                Re: Implementing lisp in Forth. Chapter 4. Paul Rubin <no.email@nospam.invalid> - 2016-09-27 00:47 -0700
                Re: Implementing lisp in Forth. Chapter 4. Spiros Bousbouras <spibou@gmail.com> - 2016-09-06 13:18 +0000
                Re: Implementing lisp in Forth. Chapter 4. "WJ" <w_a_x_man@yahoo.com> - 2016-09-06 20:52 +0000
                Re: Implementing lisp in Forth. Chapter 4. albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-11-02 19:15 +0100
                Re: Implementing lisp in Forth. Chapter 4. Lars Brinkhoff <lars.spam@nocrew.org> - 2016-09-09 10:05 +0200
                Re: Implementing lisp in Forth. Chapter 4. anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-09-12 10:11 +0000
                Re: Implementing lisp in Forth. Chapter 4. Lars Brinkhoff <lars.spam@nocrew.org> - 2016-09-12 13:15 +0200
                Re: Implementing lisp in Forth. Chapter 4. anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-09-12 17:25 +0000
                Re: Implementing lisp in Forth. Chapter 4. albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-09-09 16:19 +0200
                Re: Implementing lisp in Forth. Chapter 4. Paul Rubin <no.email@nospam.invalid> - 2016-09-09 10:55 -0700
                Re: Implementing lisp in Forth. Chapter 4. albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-09-09 21:39 +0200
                Re: Implementing lisp in Forth. Chapter 4. Paul Rubin <no.email@nospam.invalid> - 2016-09-09 13:06 -0700
                Re: Implementing lisp in Forth. Chapter 4. franck.bensusan@gmail.com - 2016-09-10 07:23 -0700
                Re: Implementing lisp in Forth. Chapter 4. Paul Rubin <no.email@nospam.invalid> - 2016-09-11 01:28 -0700
                Re: Implementing lisp in Forth. Chapter 4. Spiros Bousbouras <spibou@gmail.com> - 2016-09-13 21:37 +0000
                Re: Implementing lisp in Forth. Chapter 4. albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-09-14 09:55 +0200
                Re: Implementing lisp in Forth. Chapter 4. franck.bensusan@gmail.com - 2016-09-14 01:04 -0700
                Re: Implementing lisp in Forth. Chapter 4. Paul Rubin <no.email@nospam.invalid> - 2016-09-13 14:40 -0700
                Re: Implementing lisp in Forth. Chapter 4. franck.bensusan@gmail.com - 2016-09-14 03:37 -0700
                Re: Implementing lisp in Forth. Chapter 4. lawrencedo99@gmail.com - 2016-09-10 01:17 -0700
                Re: Implementing lisp in Forth. Chapter 4. Paul Rubin <no.email@nospam.invalid> - 2016-09-10 12:01 -0700
                Re: Implementing lisp in Forth. Chapter 4. lawrencedo99@gmail.com - 2016-09-10 21:57 -0700
                Re: Implementing lisp in Forth. Chapter 4. Paul Rubin <no.email@nospam.invalid> - 2016-09-10 22:12 -0700
                Re: Implementing lisp in Forth. Chapter 4. lawrencedo99@gmail.com - 2016-09-10 23:30 -0700
                Re: Implementing lisp in Forth. Chapter 4. Paul Rubin <no.email@nospam.invalid> - 2016-09-10 23:48 -0700
                Re: Implementing lisp in Forth. Chapter 4. Andrew Haley <andrew29@littlepinkcloud.invalid> - 2016-09-11 02:59 -0500
                Re: Implementing lisp in Forth. Chapter 4. Paul Rubin <no.email@nospam.invalid> - 2016-09-11 01:16 -0700
                Re: Implementing lisp in Forth. Chapter 4. lawrencedo99@gmail.com - 2016-09-11 19:02 -0700
                Re: Implementing lisp in Forth. Chapter 4. lawrencedo99@gmail.com - 2016-09-11 19:00 -0700
                Re: Implementing lisp in Forth. Chapter 4. Paul Rubin <no.email@nospam.invalid> - 2016-09-10 12:08 -0700
                Re: Implementing lisp in Forth. Chapter 4. anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-09-12 09:43 +0000
                Re: Implementing lisp in Forth. Chapter 4. albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-09-12 13:42 +0200
                Re: Implementing lisp in Forth. Chapter 4. anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-09-12 17:26 +0000
                Re: Implementing lisp in Forth. Chapter 4. albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-09-12 20:56 +0200
                Re: Implementing lisp in Forth. Chapter 4. Paul Rubin <no.email@nospam.invalid> - 2016-09-12 13:08 -0700
                Re: Implementing lisp in Forth. Chapter 4. anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-09-14 07:38 +0000
    Re: Implementing lisp in Forth. Chapter 4. Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2016-09-30 07:48 +0100
      Re: Implementing lisp in Forth. Chapter 4. albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-09-30 11:22 +0200
      Re: Implementing lisp in Forth. Chapter 4. Paul Rubin <no.email@nospam.invalid> - 2016-09-30 18:36 -0700
        Re: Implementing lisp in Forth. Chapter 4. albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-10-01 11:19 +0200
          Re: Implementing lisp in Forth. Chapter 4. luser droog <mijoryx@yahoo.com> - 2016-10-01 19:34 -0700
  Implementing lisp in Forth. Garbage collection. albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-09-06 12:30 +0200
    Re: Implementing lisp in Forth. Garbage collection. Spiros Bousbouras <spibou@gmail.com> - 2016-09-06 15:34 +0000
      Re: Implementing lisp in Forth. Garbage collection. albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-09-06 21:12 +0200
    Re: Implementing lisp in Forth. Garbage collection. Paul Rubin <no.email@nospam.invalid> - 2016-09-06 14:52 -0700
      Re: Implementing lisp in Forth. Garbage collection. albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-09-07 01:50 +0200
        Re: Implementing lisp in Forth. Garbage collection. Paul Rubin <no.email@nospam.invalid> - 2016-09-06 17:49 -0700
  Re: Implementing lisp in Forth. Chapter 4. luser droog <mijoryx@yahoo.com> - 2016-10-21 17:02 -0700
    Re: Implementing lisp in Forth. Chapter 4. albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-10-22 02:43 +0200

csiph-web