Re: Imperative Query Languages

On Wed, 5 Jul 2017 at 14:36 Peter Geoghegan pg(at)bowt(dot)ie
<http://mailto:pg(at)bowt(dot)ie> wrote:

However, the OP seemed to be describing something that maps imperative
> code to a declarative SQL query or something equivalent, which isn't
> quite the same thing. The declarative nature of SQL feels restrictive
> or at least unfamiliar to many programmers.
>
Yes, that is what I am describing.

SQL is great and I am fully on board with the idea. Everywhere I go, I
promote the greatness of SQL, of the relational model, and of Postgres. I
didn’t write in so much to challenge SQL or pitch navigational databases,
as to ask about examples of “pseudo-imperative” languages.

Fortress is the most noteworthy of these; but anyone who’s seen Haskell’s do
notation realizes there is some promise in the idea: the imperative
structure makes some programs much clearer, even in a pure functional
language.

IMV, what the OP describes wouldn't work well because it would
> superficially *appear* to not be restrictive in the way that some
> people dislike, but actually would be just as restrictive. The only
> way you could write it is by imagining what the SQL it produced looks
> like.

It’s not so much that SQL is restrictive, as that it is confusing in parts.
It is the same with regards to Haskell without do notation — the chained
lambdas boggle the mind. Another — very similar — idea is futures as an
approach to getting around callbacks — they create the appearance of a
linear sequence of execution, when some parts might be parallel; but this
turns out to be a benefit overall. Yet another is using while read x in
shell pipelines — an imperative structure, yet used to model stream
processing.

But this is perhaps neither here nor there: it seems there are no such
languages, no logic languages disguised as imperative languages. There are
only a very few functional languages disguised as imperative languages.
It’s an idea that has interested me for many a year — for the reasons that
Peter cites — and not having seen any language wholly organized in this
way, I thought I’d write to ask you all if you had seen any.

Kind Regards,

Jason
​