From: silas poulson <silas8642@hotmail.co.uk>
To: Will Senn <will.senn@gmail.com>
Cc: COFF <coff@minnie.tuhs.org>
Subject: Re: [COFF] Tail-recursion was Re: [TUHS] Lorinda Cherry
Date: Wed, 23 Feb 2022 00:53:04 +0000 [thread overview]
Message-ID: <A2DEB13F-C738-4EC5-A7C4-F54B5B8E9BD0@hotmail.co.uk> (raw)
In-Reply-To: <52dac66b-3f10-fc5f-9325-a8f4f9bdcc99@gmail.com>
Yes! That’s such as fun presentation!
For those who want the fast version, skip to 6:00 mark.
Silas
> On 23 Feb 2022, at 00:48, Will Senn <will.senn@gmail.com> wrote:
>
> My all time favorite presentation on tail-recursion:
>
> https://www.youtube.com/watch?v=-PX0BV9hGZY
>
>
> On 2/22/22 4:39 AM, Ralph Corderoy wrote:
>> Hi Otto,
>>
>>> MacOS uses the GNU implementation which has a long standing issue with
>>> deep recursion. It even cannot handle the tail recursive calls used
>>> here and will run out of its stack.
>> When learning dc and seeing it relied on tail calls, the first thing
>> I did was check it did tail-call elimination, and it did. That was
>> GNU dc.
>>
>> Trying just now, I see no growth in memory usage despite heavy CPU load
>> shown by TIME increasing.
>>
>> $ dc
>> !ps u `pidof dc`
>> USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
>> ralph 11489 0.0 0.0 2332 1484 pts/1 S+ 10:33 0:00 dc
>> [lmx]smlmx
>> ^C
>> Interrupt!
>> !ps u `pidof dc`
>> USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
>> ralph 11489 75.5 0.0 2332 1488 pts/1 S+ 10:33 0:46 dc
>>
>> The memory used remained at that level during the macro execution too,
>> watched from outside.
>>
>> Do you have more detail on what GNU dc can't handle? dc without
>> tail-call elimination is a bit crippled.
>>
>
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next prev parent reply other threads:[~2022-02-24 0:18 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CAKH6PiVi+JoxDG7ACMG5G+qnTkxTMsohGx6Wq3UNVkogO4N0Vg@mail.gmail.com>
[not found] ` <CAKr6gn2pJROQNr3M+JGU1vs3bRRh3SrTS5N-8w+vWP2oApwmsw@mail.gmail.com>
[not found] ` <alpine.BSF.2.21.9999.2202161122500.45073@aneurin.horsfall.org>
[not found] ` <202202160754.21G7sbUa011318@freefriends.org>
[not found] ` <1nKFRN-4IZ-00@marmaro.de>
[not found] ` <8735kig8vb.fsf@vuxu.org>
[not found] ` <m27d9tw9fx.fsf@thuvia.hamartun.priv.no>
[not found] ` <alpine.BSF.2.21.9999.2202180810480.45073@aneurin.horsfall.org>
[not found] ` <4E3028A1-EC08-424A-B814-CC2AEEEAEC7B@iitbombay.org>
[not found] ` <Yg9Z7Y8RK2+GQeDI@clue.drijf.net>
[not found] ` <20220222103948.1B0482206F@orac.inputplus.co.uk>
2022-02-23 0:48 ` Will Senn
2022-02-23 0:53 ` silas poulson [this message]
2022-02-23 1:45 ` Charles H. Sauer (he/him)
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