% versus $

[Waldek Hebisch]

For many years internally Spad compiler and interpreter renamed
'%' to '$' and internally used '$'. I have now commited a patch
that disables this renaming so that '%' from source is internally
represented by itself, without renaming. This should slightly
simplify structure of Spad compiler and interpreter, but main
gain should be in debugging: Lisp data structures should be
more similar to Spad source, so easier to interpret.

There is also related cost: patch touches a lot of places in
interp subdirectory and potentially may introduce bugs.

--
Waldek Hebisch

[Ralf Hemmecke]

On 22.04.23 22:02, Waldek Hebisch wrote:
> For many years internally Spad compiler and interpreter renamed
> '%' to '$' and internally used '$'. I have now commited a patch
> that disables this renaming so that '%' from source is internally
> represented by itself, without renaming.

Wonderful! Thank you.

Ralf

[Grégory Vanuxem]

Thanks for the information. 

Good I think. Thanks again. 

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[Tim Daly]

Historically this change was introduced because of the Aldor compiler.

There was a clash of the use of the symbols. I had to rewrite code to

get Scratchpad (Axiom) and Asharp (Aldor) to work together.

[Waldek Hebisch]

On Sat, Apr 22, 2023 at 09:00:23PM -0700, Tim Daly wrote:
> Historically this change was introduced because of the Aldor compiler.

Well, this was desirable change to Spad language. Aldor was a new
start, so it was easier to make change in Aldor first. But
it was good change for Spad.

> There was a clash of the use of the symbols. I had to rewrite code to
> get Scratchpad (Axiom) and Asharp (Aldor) to work together.

Yes. Around 1990 using symbol renaming was right thing to do, otherwise
change would require too much effort. But we want to move forward...

>
> On Saturday, April 22, 2023 at 3:19:32 PM UTC-4 Waldek Hebisch wrote:
>
> > For many years internally Spad compiler and interpreter renamed
> > '%' to '$' and internally used '$'. I have now commited a patch
> > that disables this renaming so that '%' from source is internally
> > represented by itself, without renaming. This should slightly
> > simplify structure of Spad compiler and interpreter, but main
> > gain should be in debugging: Lisp data structures should be
> > more similar to Spad source, so easier to interpret.
> >
> > There is also related cost: patch touches a lot of places in
> > interp subdirectory and potentially may introduce bugs.
> >
> > --
> > Waldek Hebisch
> >
>

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--
Waldek Hebisch

[Tim Daly]

Reasonable people can disagree, even about history.

I believe it was a mistake to implement the Aldor compiler in C.

Implementing a new compiler inside Scratchpad would have cleaned

up the Spad language, the Spad compiler, and made the

interpreter/compiler semantic difference disappear. It would

also have been a much smaller effort as most of the machinery

already existed.

Dick Jenks thought the same thing but Stephen argued that we

could re-implement the algebra in the C version (which was

eventually my PhD task). Is there any Aldor algebra in the

build process?

I taught a compiler course at Vassar and used some examples

from Aldor. It is a very pretty piece of software written by brilliant

programmers. However, there are more people that "speak boot"

than "speak Aldor" and that is already a vanishingly small number.

> it was good change for Spad.

The huge effort would have been better spent developing more algebra

or, as I argued then and now, developing specification/proof technology

inside Scratchpad. Reasonable people disagree with me :-)

The point is moot. Aldor exists.