plusto operator definition missing?

[chris hermansen]

Good day, Jose & list;

On Sun, Jul 13, 2025 at 1:24 PM Jose E. Marchesi <jemarch@gnu.org> wrote:

>
> > Hello all,
> >
> > I was going through Lindsey a couple of days ago and noticed the plusto
> > operator definition on p. 244.  Here is what it says:
> >
> > operator priority mode of a  mode of b  mode of result  meaning
> > plusto       1      string  ref string    ref string   b := a + b
> > +=:                  char   ref string    ref string
> >
> > (I hope that shows up ok in peoples' email; I did it in fixed width text)
> >
> > I have a version of the procedure "whole" that I use with GNU Algol 68
> that
> > has the line
> >
> > digit_string := digit_char + digit_string
> >
> > in it, and I thought I'd try +=: instead, as in:
> >
> > digit_string +=: digit_char
> >
> > However, ga68 complains:
> >
> > testl.a68:277:50: error: CHAR cannot be coerced to REF STRING in this
> > context
> >   277 |                                 digit_string +=: digit_char;
> >
> > I am supposing that this is due to not having the second version of the
> > operator defined - the one that works with a char on the right hand side.
> >
> > Am I missing something?  Thanks in advance.
>
> I think you mean:
>
>     digit_char +=: digit_string;
>
> Which works as expected.
>

So I tried this, but I think it does not work as expected.

Again, referring to Lindsey p. 244

a +=: b

is supposed to be equivalent to

b := a + b

That is, the point of plusto is to prepend rather than append.

But it seems like GNU Algol 68 is generating

b := b + a

Perhaps I've missed something?

-- 
Chris Hermansen · clhermansen "at" gmail "dot" com

C'est ma façon de parler.
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