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From: roconnor@theorem.ca
To: Chris Double <chris.double@double.co.nz>
Cc: bitcoin-development@lists.sourceforge.net
Subject: Re: [Bitcoin-development] Alternative to OP_EVAL
Date: Fri, 30 Dec 2011 12:19:24 -0500 (EST)	[thread overview]
Message-ID: <alpine.LRH.2.00.1112301214380.9419@theorem.ca> (raw)
In-Reply-To: <CALn1vHHjY6Qq0zEUcWaNzm_eP_JekjrK26zMXfcrfPSydwSKig@mail.gmail.com>

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On Sat, 31 Dec 2011, Chris Double wrote:

> On Fri, Dec 30, 2011 at 5:42 AM,  <roconnor@theorem.ca> wrote:
>> Basically OP_DUP lets you duplicate the code on the stack and that is the
>> key to looping.  I'm pretty sure from here we get get Turing completeness.
>> Using the stack operations I expect you can implement the SK-calculus
>> given an OP_EVAL that allows arbitrary depth.
>>
>> OP_EVAL adds dangerously expressive power to the scripting language.
>
> If you look at the archives of the concatenative programming mailing
> list [1] you'll see lots of examples of people creating stack
> languages with minimal operations that exploit similar functionality
> to reduce the required built in operations. The discussion on the list
> is mostly about stack based languages where programs can be pushed on
> the stack and executed (eg. Joy [2]/Factor/Some Forths).
>
> I don't think the scripting engine in bitcoin has the ability to
> concatenate, append or otherwise manipulate scripts on the stack to be
> eval'd though does it?

It will limited ability manipulate scripts on the stack through the use of 
arithmetic and hashing operations, and if OP_CAT, OP_SUBSTR and friends 
are ever restored, it will have even more abilities.

-- 
Russell O'Connor                                      <http://r6.ca/>
``All talk about `theft,''' the general counsel of the American Graphophone
Company wrote, ``is the merest claptrap, for there exists no property in
ideas musical, literary or artistic, except as defined by statute.''

  reply	other threads:[~2011-12-30 17:19 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-12-29  6:55 [Bitcoin-development] Alternative to OP_EVAL roconnor
2011-12-29  8:44 ` theymos
2011-12-29 16:42   ` roconnor
2011-12-30 12:01     ` Chris Double
2011-12-30 17:19       ` roconnor [this message]
2012-01-02 15:14         ` Stefan Thomas
2012-01-02 15:59           ` Gavin Andresen
2012-01-02 16:42             ` roconnor
2012-01-02 17:10             ` Stefan Thomas
2011-12-31  9:54     ` Joel Joonatan Kaartinen
2011-12-31 17:28       ` Zell Faze
2011-12-29 16:23 ` Gavin Andresen
2011-12-29 17:01   ` roconnor
2011-12-29 17:06     ` Luke-Jr
2011-12-29 18:00     ` Gavin Andresen
2011-12-29 19:54       ` Stefan Thomas
2011-12-29 19:08 ` Pieter Wuille
2011-12-29 21:00   ` Pieter Wuille
2011-12-29 21:31   ` Alan Reiner

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