wtanksley@bigfoot.com — 2000-06-19 23:25:15

From: stevan apter [mailto:apter@...]

>fellow concatenators:
>in joy:
> joy>5 3 -
> 2
>but as i've implemented the primitives in conk:
> k>5 3 -
> -2
>i prefer the conk interpretation, since [3 -] is then the program which
>subtracts the item on the top of the stack from 3, which seems
>more natural than the program which subtracts 3 from the top of the
>stack.

Could you clarify this preference? I don't find either one particularly
natural (or unnatural).

The only reason I can see to impose one order over the other is tradition:
both infix ordering and prefix ordering. In infix, "5 3 -" easily morphs
into "5 - 3" simply by moving the operator, and the same rule applies to all
the appropriate operators. The same mapping holds true for Lisp and Scheme
in prefix, so Forth isn't the only language or notation to follow this
guideline.

>this wasn't intentional, except insofar as i want the conk primitives
>to be mapped by one rule to the k primitives. if i reverse
>the arguments
>of -, then i would have to do that everywhere, and the resulting set of
>primitives is extremely cumbersome.

That's actually a good reason to do it your way. I'm not sure that it's
strong enough (it wouldn't be for me; I like the traditional way), but I
have no personal objections either way.

-Billy

stevan apter — 2000-06-20 12:16:04

----- Original Message -----
From: <wtanksley@...>
To: <concatenative@egroups.com>
Sent: Monday, June 19, 2000 7:25 PM
Subject: RE: [stack] the order of arguments

> From: stevan apter [mailto:apter@...]
>
> >fellow concatenators:
> >in joy:
> > joy>5 3 -
> > 2
> >but as i've implemented the primitives in conk:
> > k>5 3 -
> > -2
> >i prefer the conk interpretation, since [3 -] is then the program which
> >subtracts the item on the top of the stack from 3, which seems
> >more natural than the program which subtracts 3 from the top of the
> >stack.
>
> Could you clarify this preference? I don't find either one particularly
> natural (or unnatural).

i suppose it's an artifact of adjusting to

-3 / negate 3
3- / the function 3-x

in (applicative) k. (my philosophy teacher david lewis used to recommend
rigorously replacing the term 'intuition' everywhere with 'opinion'.)

>
> The only reason I can see to impose one order over the other is tradition:
> both infix ordering and prefix ordering. In infix, "5 3 -" easily morphs
> into "5 - 3" simply by moving the operator, and the same rule applies to all
> the appropriate operators. The same mapping holds true for Lisp and Scheme
> in prefix, so Forth isn't the only language or notation to follow this
> guideline.
>
> >this wasn't intentional, except insofar as i want the conk primitives
> >to be mapped by one rule to the k primitives. if i reverse
> >the arguments
> >of -, then i would have to do that everywhere, and the resulting set of
> >primitives is extremely cumbersome.

well, perhaps it isn't as awkward as i thought. i'll follow tradition.

>
> That's actually a good reason to do it your way. I'm not sure that it's
> strong enough (it wouldn't be for me; I like the traditional way), but I
> have no personal objections either way.

now if only i could remember which is the top of the stack in
stack-notation! the hardest part of implementing joy is putting
the list-reversals in the right place!

>
> -Billy
>
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wtanksley@bigfoot.com — 2000-06-20 17:24:33

From: stevan apter [mailto:apter@...]

>From: <wtanksley@...>

>in (applicative) k. (my philosophy teacher david lewis used
>to recommend
>rigorously replacing the term 'intuition' everywhere with 'opinion'.)

I like that -- it's a good way to put it. I also disbelieve in
'intuitiveness'. I like 'affordance', where a new concept can be made
learnable by deliberately inserting parts of an already-known old concept
(like Forth preserving infix ordering, or conk preserving k ordering, or
icons having subtitles).

>now if only i could remember which is the top of the stack in
>stack-notation! the hardest part of implementing joy is putting
>the list-reversals in the right place!

sa@dfa.com — 2000-06-20 19:00:51

>now if only i could remember which is the top of the stack in
>stack-notation! the hardest part of implementing joy is putting
>the list-reversals in the right place!

Would it help to keep in mind that if a stack notation could be executed,
with each item pushing one thing onto the stack, the last item would be on
top of the stack?

So, in ( x y z -- n ), when you're reading it (at least until you can
remember without effort), you'd think "okay, push x, then y, then z -- z is
on top."

my confusion is the result of shifting between
the representation and the represented. my stack
is a list, and its top is the first item, which
is "naturally" on the left.

but i think i've finally internalized the distinction.
thanks!

-Billy

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wtanksley@bigfoot.com — 2000-06-25 00:30:50

From: sa@... [mailto:sa@...]

> my confusion is the result of shifting between
> the representation and the represented. my stack
> is a list, and its top is the first item, which
> is "naturally" on the left.

That makes a lot of sense -- I had a similar problem as well, even though
I've been using Forth for a long time now. (My problem was not recognising
how to use a list to do these things, duh. :-)

-Billy