Re: Does Codd's view of a relational database differ from that ofDate&Darwin?[M.Gittens]
From: VC <boston103_at_hotmail.com>
Date: Mon, 20 Jun 2005 22:11:32 -0400
Message-ID: <J9GdnQcemqCl6irfRVn-iA_at_comcast.com>
> For all intents and purposes the 'print' word is just a keyword in
> DAPLEX and could be easily replaced with something like the 'return' in
> XQuery.
> From the way I used it you might have guessed that I meant pure ML. The
> print statement is only there to say that you return a concatenation of
> values and that you can do in pure ML.
> I don't have to spoon feed you everything, do I? :-)
Date: Mon, 20 Jun 2005 22:11:32 -0400
Message-ID: <J9GdnQcemqCl6irfRVn-iA_at_comcast.com>
"Jan Hidders" <jan.hidders_at_REMOVETHIS.pandora.be> wrote in message
news:6AHte.125958$a67.7010345_at_phobos.telenet-ops.be...
> vc wrote:
>> Jan Hidders wrote:
[...]
>>>> for each s in employee print(getName(s), getAge(s), >>>> getName(getBuilding(getDepartment(s)))) >>> >>> What's imperative about this? Where are the assignments? Where are >>> the while loops? >> >> Why, the 'print' word of course as I wrote earlier. >
> For all intents and purposes the 'print' word is just a keyword in
> DAPLEX and could be easily replaced with something like the 'return' in
> XQuery.
That is correct. However, in XQuery, the 'return' is just a 'print' (or an assignment) in disguise. This 'return' thingy, among others, is what makes XQuery 'impure'. Just think about what would be a definition for a function called 'return' in a pure FL ? What kind of mapping would it describe ?
> >>>> ... which might make one to assume a mental navigational model >>>> for the entire language, rather than declarative/functional >>>> ['functional' as in functional programming] one. >>> >>> If your above example would be written in ML it would look roughly >>> the same. >> >> I am sure you know that ML is *not* a pure FL and the fragment in >> question would be imperative there too thanks to 'print' or whatever >> ML uses. >
> From the way I used it you might have guessed that I meant pure ML. The
> print statement is only there to say that you return a concatenation of
> values and that you can do in pure ML.
> >>> Defining views might be, but it's not clear to me how deep that >>> problem is. What exactly would a "view" be in this context anyway? >> >> You tell me ;) >
> I don't have to spoon feed you everything, do I? :-)
Why not, just for a change ;)
vc
>
> -- Jan Hidders
Received on Tue Jun 21 2005 - 04:11:32 CEST