Re: Bitcoin scripting language extensions, collaboration requested

Jorge Timón <[email protected]> Wed, 5 Mar 2014 11:21:13 -0800
Newsgroups	gmane.comp.lang.concatenative
Message-ID	<CAC1+kJNFw-C8xqWt92SuWsLeq0aR2rnUsQGdPG9fZwBWsyKkNg@mail.gmail.com>
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First, I want to thank you all for helping us on this.

On 2/5/14, John Nowak <[email protected]> wrote:
> The ability to easily calculate resource bounds is precisely due to the
> restriction to first-order, recursion-free, allocation-free code: You
> can just go through the call tree statically and calculate the maximum
> height of the stack. The same thing would be possible even if it offered
> no support for proof.

This sounds very good.
I don't think we need dynamic allocation, you should be able to do
anything just using the stack.
Recursion seems intuitively dangerous for attacks like loop bombs.

On the bytecode vs readable language discussion, although there's no
reason why someone couldn't use a more powerful language that gets
compiled to the base scripting, probably most contracts will be
written by hand. So although readability is not the first priority, it
would certainly be something nice to have.

One thing I'm not sure it's being considered related to requirement d
(merkle tree structure) is the ability for a script to select concrete
parts from another script (we generically call these "extrospection
operations" which may refer to other scripts and other merkle tree
structures in the system like the unspent transaction outputs set
UTXO).
I'm sorry this probably sounds too abstract, probably we should start
with some simpler examples first after Mark writes the set of basic
crypto primitives.
To get a sense of what's now possible, you can read this:

https://en.bitcoin.it/wiki/Script

Well, most operands are actually currently disabled, but still there
are some simple allowed transactions at the end.
This is probably interesting to read as well (although some of them
aren't actually currently allowed either):

https://en.bitcoin.it/wiki/Contracts

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      <p>First, I want to thank you all for helping us on this.<br>
<br>
On 2/5/14, John Nowak &lt;[email protected]&gt; wrote:<br>
&gt; The ability to easily calculate resource bounds is precisely due to the<br>
&gt; restriction to first-order, recursion-free, allocation-free code: You<br>
&gt; can just go through the call tree statically and calculate the maximum<br>
&gt; height of the stack. The same thing would be possible even if it offered<br>
&gt; no support for proof.<br>
<br>
This sounds very good.<br>
I don&#39;t think we need dynamic allocation, you should be able to do<br>
anything just using the stack.<br>
Recursion seems intuitively dangerous for attacks like loop bombs.<br>
<br>
On the bytecode vs readable language discussion, although there&#39;s no<br>
reason why someone couldn&#39;t use a more powerful language that gets<br>
compiled to the base scripting, probably most contracts will be<br>
written by hand. So although readability is not the first priority, it<br>
would certainly be something nice to have.<br>
<br>
One thing I&#39;m not sure it&#39;s being considered related to requirement d<br>
(merkle tree structure) is the ability for a script to select concrete<br>
parts from another script (we generically call these &quot;extrospection<br>
operations&quot; which may refer to other scripts and other merkle tree<br>
structures in the system like the unspent transaction outputs set<br>
UTXO).<br>
I&#39;m sorry this probably sounds too abstract, probably we should start<br>
with some simpler examples first after Mark writes the set of basic<br>
crypto primitives.<br>
To get a sense of what&#39;s now possible, you can read this:<br>
<br>
https://en.bitcoin.it/wiki/Script<br>
<br>
Well, most operands are actually currently disabled, but still there<br>
are some simple allowed transactions at the end.<br>
This is probably interesting to read as well (although some of them<br>
aren&#39;t actually currently allowed either):<br>
<br>
https://en.bitcoin.it/wiki/Contracts<br>
</p>

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