Received: from sog-mx-2.v43.ch3.sourceforge.com ([172.29.43.192] helo=mx.sourceforge.net) by sfs-ml-4.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1Rgg7A-0005Si-Qh for bitcoin-development@lists.sourceforge.net; Fri, 30 Dec 2011 17:19:32 +0000 X-ACL-Warn: Received: from erdos.theorem.ca ([72.2.4.176] helo=theorem.ca) by sog-mx-2.v43.ch3.sourceforge.com with smtp (Exim 4.76) id 1Rgg77-0000VK-RG for bitcoin-development@lists.sourceforge.net; Fri, 30 Dec 2011 17:19:32 +0000 Received: (qmail 10333 invoked by uid 603); 30 Dec 2011 17:19:24 -0000 Received: from localhost (sendmail-bs@127.0.0.1) by localhost with SMTP; 30 Dec 2011 17:19:24 -0000 Date: Fri, 30 Dec 2011 12:19:24 -0500 (EST) From: roconnor@theorem.ca To: Chris Double In-Reply-To: Message-ID: References: <1325148259.14431.140661016987461@webmail.messagingengine.com> User-Agent: Alpine 2.00 (LRH 1167 2008-08-23) MIME-Version: 1.0 Content-Type: MULTIPART/MIXED; BOUNDARY="38318084-1849012031-1325265564=:9419" X-Spam-Score: -1.5 (-) X-Spam-Report: Spam Filtering performed by mx.sourceforge.net. See http://spamassassin.org/tag/ for more details. -1.3 RP_MATCHES_RCVD Envelope sender domain matches handover relay domain -0.2 AWL AWL: From: address is in the auto white-list X-Headers-End: 1Rgg77-0000VK-RG Cc: bitcoin-development@lists.sourceforge.net Subject: Re: [Bitcoin-development] Alternative to OP_EVAL X-BeenThere: bitcoin-development@lists.sourceforge.net X-Mailman-Version: 2.1.9 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 30 Dec 2011 17:19:32 -0000 This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. --38318084-1849012031-1325265564=:9419 Content-Type: TEXT/PLAIN; charset=iso-8859-1; format=flowed Content-Transfer-Encoding: 8BIT On Sat, 31 Dec 2011, Chris Double wrote: > On Fri, Dec 30, 2011 at 5:42 AM, 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 ``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.'' --38318084-1849012031-1325265564=:9419--