Sampo Syreeni wrote:
I think I agree with that but this doesn't mean I'm inclined that way.
Rather, I think it is still the case that nobody has even specified a
minimal language for a 'Codd machine', because even such a magnificent
effort as Tutorial D goes far beyond what is necessary. In the case of
Tutorial D, I'm pretty sure that this is because of the 'procedural'
perspective and also because D&D pay homage to physical traditions
involving concurrency and device techniques and an implied seamless
progression away from sql. I don't say their motivation is wrong for
them, but personally I could care less about the SQL legacy nor all the
mis-specified db's out there, many of them built on ambiguous requirements.


For example, Date, and I presume Darwen, holds to the meaning of the
Information Principle as being that all information is recorded in
D&D-style relvars. But as stated, there is no reason I can see why
relvars must be reference-able in a language, the environment could make
them implicit. From a purist's point-of-view, aspects such as
transactions are also meaningless, it would be enough to have a
single-threaded process for writing, this process could be supplied with
the results of all queries that determine what is to be written. There
is no 'need' to start a transaction.


It is easy enough to implement write-once variables, instead of
'relvars', let me call them 'wovars'. Eg., R might be 'understood' as a
relational value available to be referenced by a minimal language's
equations. R' might be understood to be a replacement for R, R'' a
replacement for R' and so forth, as the LISP people might say, 'lots of
silly idiotic apostrophes', but this has tremendous upshot for
pedestrians like me, such as no assignment so no need for 'multiple
assignment', no problems of sequence.


I often think that had today's physical speeds and memory capacities
been available forty years ago, nobody would have thought twice about
avoiding double reads. The SQLITE virtual machine offers a very viable
platform for doing this. A proof-of-concept wouldn't be very hard to
produce even in javascript/ecmascript and not much harder in faster but
ironically less portable C. Firefox provides some graphical support for
all this. I doubt if the author of SQLITE had something other in mind
than SQL for a user language and it does seem that certain parts of his
vm are tailored towards SQL but I don't think they'd be too troublesome.
Such a language would be pretty much a direct implementation of D&D's
A-algebra or very close to it, perhaps with slightly different
fundamental ops.


I've thought more than once about trying this because I think it is
easily within the reach of a solo developer, eg., less than 15,000 lines
total, given the right starting environment, assuming pretty dedicated
habits and discipline. Not sure I have those anymore, too many other
hobbies.


As for your orientation, personally I think it's more important to first
see a true Codd machine, after all the host languages I've suggested are
more or less capable of what you want.

paul c wrote:
I meant to say I'm not inclined to do anything about it.

paul c wrote:
Sorry for the sloppiness, should have added that I think as desireable
for possible convenience as many people think support for inheritance
is, I don't think it's absolutely necessary, I believe D&D don't
consider it mandatory either.

Really, all I'm saying is that things become pretty simple once one
becomes willing to delete extraneous historical requirements.