Re: [stack] function/object ambiguity + quotation alternative

On Feb 26, 2009, at 1:06 PM, Stevan Apter wrote:

> i see the problem.  in XY, [X]first != [X]i.
> i moves the top of the stack to the head of the queue, whence it  
> executes,
> immediately.
> first replaces the top of the stack with the first element of the  
> top of
> the stack.

Your assessment that the problem is '[X]first != [X]i' is incorrect.

Currently in XY, this is true:

    [dup] first i  ==  [dup] i

The problem is that this means I can prove that 'first' is the  
identity function.

If we change XY such that '[dup] first == [dup] i', I can take this:

    [dup] first i  ==  [dup] i

And substitute '[dup] i' for '[dup] first':

    [dup] i i  ==  [dup] i

And hence I can prove 'i i == i', and then from there prove that 'i'  
is the identity function.

The only way to solve this problem is to have '[dup] first i' cause an  
error. 'i' must be correctly restricted to performing "dequotation" as  
in Joy, Factor, Cat, etc.

- John