Standard prelude version Hans van Vliet

[chris hermansen]

Belatedly, thanks for sending this link

https://www.dickgrune.com/CS/Algol68/TransputHansVanVliet

I feel like I could start plugging away at it.  Almost...

The various "PseudoNN" modes need some thought; or at least, the first
dozen or so that I've examined.  As I understand it, van Vliet's idea here
is to leave flexibility to the implementor in the definition of e.g. mode
BOOK that suits her/his operating system target.

Is that the general idea?

I find the concept of "mode BOOK" to be a bit fuzzy within the framework
established by Unix / Linux / (even) Windows.  As I understand it, a BOOK
refers to the semantic structure of data contained within a FILE.  This
kind of reminds me of IBM mainframe days (daze?) when we used to put data
structures (or at least 80 column records, blocked) into files and read
them back out, thus FILE corresponding to a stream of bytes and BOOK
corresponding to the data (or record, at least) structure itself.

Am I fully lost here?

Also I get completely nervous every time I see the whole ℵ0 thing which
deeply infects transput.  I feel like the spirit of Georg Cantor is looking
over my shoulder.  For example, from RR § 25.3.1.1

MODE ℵ0 BOOK =
    STRUCT (FLEXTEXT text,
        POS lpos ¢ logical end of book ¢,
        STRING idf ¢ identification ¢,
        BOOL putting ¢ TRUE if the book may be written to ¢,
        INT users ¢ the number of times the book is opened ¢);

So the RR 25.1.3 states, in Step 2:

If, in some form, as possibly made in the step above, ℵ0 occurs followed by
an INDICATOR (a field-selector) I, then that occurrence of ℵ0 is deleted
and each INDICATOR (field-selector) akin {151 .1.3.2.k} to I contained in
any form is replaced by a copy of one same INDICATOR (field-selector) which
does not occur elsewhere in the program and Step 2 is taken again.

Maybe the authors of the revised report felt Georg giving them the stink
eye as well, since they replaced the ℵ0 with the dash-question-mark symbol;
but as far as I can tell, ultimately it's not the symbol that's giving me
the heebiejeebies here, it's what do do about it.

That is, I don't understand - at all - the significance of ℵ0 in the
definition of the BOOK mode above.

For instance, "ℵ0 occurs followed by an INDICATOR (a field-selector)" - how
closely is "followed"?  "FLEXTEXT text" follows ℵ0 (eventually); does that
count?  Or does the intervening "STRUCT" "OPEN-SYMBOL" preclude the
deletion of ℵ0 in this case?

Put another way, does

MODE BOOK =
    STRUCT (FLEXTEXT text,
        POS lpos ¢ logical end of book ¢,
        STRING idf ¢ identification ¢,
        BOOL putting ¢ TRUE if the book may be written to ¢,
        INT users ¢ the number of times the book is opened ¢);

ie without the ℵ0, have the same semantic import?

Moving on to a concrete question, Jose, do you see sppp dealing with these
ℵ0 things?  Or will we need some other pre-processor to accomplish what is
needed?  Or can we move to the super-language instead?

I hope the readers of this list 1) understand my questions and 2) can
enlighten me as I would love to contribute to this project.

Thanks in advance for patience and enlightenment.


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

C'est ma façon de parler.
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