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From: Luke Durback <luke.durback@gmail.com>
Date: Wed, 9 Dec 2015 20:35:17 -0500
Message-ID: <CAEj3M+wYicoACcpG5YUU6vF8vg98XCcJWmgBiyrJj-xHHxrhig@mail.gmail.com>
To: bitcoin-dev@lists.linuxfoundation.org
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Subject: [bitcoin-dev] Standard BIP Draft: Turing Pseudo-Completeness
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Hello Bitcoin-Dev,

I hope this isn't out of line, but I joined the mailing list to try to
start a discussion on adding opcodes to make Script Turing Pseudo-Complete
as Wright suggested is possible.

---

In line with Wright's suggestion, I propose adding a return stack alongside
the, already existing, control stack.

The principle opcodes (excluding conditional versions of call and
return_from) needed are

OP_DEFINITION_START FunctionName:  The code that follows is the definition
of a new function to be named TransactionSenderAddress.FunctionName.  If
this function name is already taken, the transaction is marked invalid.
Within the transaction, the function can be called simply as FunctionName.

OP_DEFINITION_END:  This ends a function definition

OP_FUNCTION_NAME FunctionName:  Gives the current transaction the name
FunctionName (this is necessary to build recursive functions)

---

OP_CALL Namespace.FunctionName Value TransactionFee:  This marks the
transaction as valid.  It also pushes the current execution location onto
the return stack, debits the calling transaction by the TransactionFee and
Value, and creates a new transaction specified by Namespace.FunctionName
with both stacks continued from before (this may be dangerous, but I see no
way around it) with the specified value.

OP_RETURN_FROM_CALL_AND_CONTINUE:  This pops the top value off the return
stack and continues from the specified location with both stacks in tact.

---

It would also be useful if a transaction can create another transaction
arbitrarily, so to prepare for that, I additionally propose

OP_NAMESPACE:  Pushes the current namespace onto the control stack

This, combined with the ability to make new transactions arbitrarily would
allow a function to pay its creator.


I understand that this isn't all that is needed, but I think it's a start.
I hope this proposal has met you all well,

Luke Durback

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<div dir=3D"ltr"><div>Hello Bitcoin-Dev,<br></div><div><br></div><div>I hop=
e this isn&#39;t out of line, but I joined the mailing list to try to start=
 a discussion on adding opcodes to make Script Turing Pseudo-Complete as Wr=
ight suggested is possible.</div><div><br></div><div>---</div><div><br></di=
v><div>In line with Wright&#39;s suggestion, I propose adding a return stac=
k alongside the, already existing, control stack.</div><div><br></div><div>=
The principle opcodes (excluding conditional versions of call and return_fr=
om) needed are</div><div><br></div><div>OP_DEFINITION_START FunctionName: =
=C2=A0The code that follows is the definition of a new function to be named=
 TransactionSenderAddress.FunctionName.=C2=A0 If this function name is alre=
ady taken, the transaction is marked invalid.=C2=A0 Within the transaction,=
 the function can be called simply as FunctionName.</div><div><br></div><di=
v>OP_DEFINITION_END: =C2=A0This ends a function definition</div><div><div><=
br></div><div>OP_FUNCTION_NAME FunctionName: =C2=A0Gives the current transa=
ction the name FunctionName (this is necessary to build recursive functions=
)</div></div><div><br></div><div>---</div><div><br></div><div>OP_CALL Names=
pace.FunctionName Value TransactionFee: =C2=A0This marks the transaction as=
 valid.=C2=A0 It also pushes the current execution location onto the return=
 stack, debits the calling transaction by the TransactionFee and Value, and=
 creates a new transaction specified by Namespace.FunctionName with both st=
acks continued from before (this may be dangerous, but I see no way around =
it) with the specified value.</div><div><br></div><div>OP_RETURN_FROM_CALL_=
AND_CONTINUE: =C2=A0This pops the top value off the return stack and contin=
ues from the specified location with both stacks in tact.</div><div><br></d=
iv><div>---<br></div><div><br></div><div>It would also be useful if a trans=
action can create another transaction arbitrarily, so to prepare for that, =
I additionally propose</div><div><br></div><div>OP_NAMESPACE: =C2=A0Pushes =
the current namespace onto the control stack<br><br>This, combined with the=
 ability to make new transactions arbitrarily would allow a function to pay=
 its creator.</div><div><br></div><div><br></div><div><br></div><div>I unde=
rstand that this isn&#39;t all that is needed, but I think it&#39;s a start=
.=C2=A0 I hope this proposal has met you all well,</div><div><br></div><div=
>Luke Durback</div></div>

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