Re: Java and Python have just discovered "record" type finally after 40 years.

[Ben Bacarisse <ben.usenet@bsb.me.uk>]

"Jeffrey R.Carter" <spam.jrcarter.not@spam.acm.org.not> writes:

> On 2023-05-14 17:14, Ben Bacarisse wrote:
>> I never saw a LISP S-expressions defined that way.  Did this list really
>> no have a "dotted pair" as the basic structure with lists being simply a
>> special case?
>
> The book I learned from (/Let's Talk LISP/ by Laurent Siklóssy, 1976)
> introduces dotted pairs in chapter 10.7.1 (out of 12 chapters) on page 145
> (out of 213, excluding appendices and index). Chapter 10 deals with the
> internal representation of data in LISP. The implication is that they were
> not considered part of the normal use of the language.

Do you still have it?  Does is discuss association lists?  I'd call them
a normal part of LISP and it would be odd to force the associations to
be lists rather than pairs.  Does Siklóssy imply that an ASSOC list is a
list of lists of length 2, or does he not discuss them until the very
end?

> S-expressions, on the other hand, are introduced in chapter 1.1 on page
> 2. The book also presents the grammar
>
> S-expression ::= atom | list
> list ::= '(' inside ')'
> inside ::= empty | S-expression | S-expression inside
> empty ::=

That's an interesting way to simplify things for the leaner though I
would not have chosen to use a term that already had another meaning by
1976.  The author could have used something like L-expression and
avoided any future confusion.

-- 
Ben.