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Re: CfV: Quotations

From Paul Rubin <no.email@nospam.invalid>
Newsgroups comp.lang.forth
Subject Re: CfV: Quotations
Date 2016-08-15 22:16 -0700
Organization A noiseless patient Spider
Message-ID <87lgzxuwdr.fsf@jester.gateway.pace.com> (permalink)
References <2016Aug10.185227@mips.complang.tuwien.ac.at> <87lh041mjx.fsf@jester.gateway.pace.com> <noqlm8$ag1$3@dont-email.me>

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Bernd Paysan <bernd.paysan@gmx.de> writes:
> : count-wl ( wid -- count )
>   >r 0 [: ( n nt -- n' flag ) drop 1+ true ;] r> traverse-wordlist ; 
> Now do that in C++, and you need to access an outer local for that.

That would be a pretty unnatural interface for traverse-wordlist in C++,
but I see what you mean.  It effectively uses the stack as a shared
global.  I guess that's ok in this setting.  In C++ traverse-wordlist
would probably return an iterator and you'd loop over it or use std::count.

> Forth is not a locals-centric language, it's a stack-centric
> language...  Without the stack, quotations would be much less useful.

Locals are optional but I'd hope quotations are even more optional?

> The problem with nested functions is not only that they are more 
> difficult to implement, it's also that they can't outlive their parent's 
> stack frame lifetime, and quotations which do are part of the use cases.

I wonder how often quotations will leave stuff on the stack for use by
the next iteration of something.  I'm used to using a HOF like "fold" or
"reduce" for that, though it would seem weird in Forth.

If you don't need any mutable global state (like the stack) then you can
pass parameters into the lambda, which can survive the parent returning.

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Thread

CfV: Quotations anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-08-10 16:52 +0000
  Re: CfV: Quotations Matthias Trute <matthias.trute@gmail.com> - 2016-08-10 11:19 -0700
  Re: CfV: Quotations Paul Rubin <no.email@nospam.invalid> - 2016-08-10 11:55 -0700
    Re: CfV: Quotations Bernd Paysan <bernd.paysan@gmx.de> - 2016-08-14 20:52 +0000
      Re: CfV: Quotations hughaguilar96@gmail.com - 2016-08-14 14:42 -0700
        Re: CfV: Quotations Julian Fondren <julian.fondren@gmail.com> - 2016-08-14 16:43 -0700
      Re: CfV: Quotations Paul Rubin <no.email@nospam.invalid> - 2016-08-15 22:16 -0700
        Re: CfV: Quotations anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-08-16 07:13 +0000
          Re: CfV: Quotations Paul Rubin <no.email@nospam.invalid> - 2016-08-18 15:30 -0700
            Re: CfV: Quotations anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-08-19 15:32 +0000
          Re: CfV: Quotations Bernd Paysan <bernd.paysan@gmx.de> - 2016-08-20 20:46 +0000
            Re: CfV: Quotations anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-08-21 09:32 +0000
              Re: CfV: Quotations hughaguilar96@gmail.com - 2016-08-21 11:06 -0700
                Re: CfV: Quotations anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-08-24 17:02 +0000
              Re: CfV: Quotations Bernd Paysan <bernd.paysan@gmx.de> - 2016-08-21 22:52 +0000
                Re: CfV: Quotations anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-08-22 13:54 +0000
                Re: CfV: Quotations Bernd Paysan <bernd.paysan@gmx.de> - 2016-08-22 23:19 +0000
                Re: CfV: Quotations anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-08-24 15:54 +0000
                Re: CfV: Quotations Bernd Paysan <bernd@net2o.de> - 2016-08-28 00:43 +0000
                Re: CfV: Quotations anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-08-28 09:53 +0000
                Re: CfV: Quotations Andrew Haley <andrew29@littlepinkcloud.invalid> - 2016-08-28 08:32 -0500
                Re: CfV: Quotations anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-08-28 14:38 +0000
  Re: CfV: Quotations mhx@iae.nl - 2016-08-10 12:02 -0700
  Re: CfV: Quotations Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2016-08-11 17:25 +0100
  Re: CfV: Quotations Julian Fondren <julian.fondren@gmail.com> - 2016-08-11 12:48 -0700
  Re: CfV: Quotations minforth@arcor.de - 2016-08-16 03:31 -0700
  Re: CfV: Quotations Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2016-08-31 15:15 +0100
    Re: CfV: Quotations anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-08-31 15:26 +0000
      Re: CfV: Quotations Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2016-09-02 22:33 +0100
        Re: CfV: Quotations anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-09-03 06:47 +0000

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