From: David Vallner <david@...>
Date: 2006-12-06T07:58:56+09:00
Subject: Re: Lisp comprehensions => SQL

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Victor "Zverok" Shepelev wrote:
> Hi all.
>=20
> Random idea, just for fun - using "list comprehensions" for SQL queries=

> generation.
>=20

I think it has been done verbatim, can't recall the library. Search the
archives?

> Also MS's LINQ and ruby's Mongoose DB seems to do something like this.
>=20

MS's LINQ does the opposite, allowing SQL-ish constructs to express list
comprehensions on steroids. Well, basically; I have my doubts about the
more relational features like joins on object collections performing any
well (no concept of the dataset, no analysis thereof to do query
planning, probably no indexing either) or making actual sense whatsoever
(why join when you can just use direct references?). From a design point
of view, I'd prefer preintegrating data into a clean domain model
instead of bridging over with the band-aid that is generalised data
structure query. It's boilerplate, more effort, and less "whoa, cool",
but you get a high level of consistency in the core business logic if
you take care of the data format impedance mismatch up front instead of
putting over a bandaid later. (No "What paradigm am I coding THIS line
in again?" issues.) The field of data modelling seems way too varied to
me for one query language / paradigm to work universally without kludges
appearing around the edges.

(For the obvious impaired: I just don't like LINQ. By far the ugliest
and most out of place addition to C#3.0.)

> But the realization of above seems to be interesting task (for RubyQuiz=
, may
> be?)
>=20

Well, to work with blocks, you'd need to involve ParseTree or something
like that, unless you're willing to offload some of the logic back to
the interpreter (gruesomely laggy). That might be a little out of scope
for a RubyQuiz. Then again, having seen some of the more golfy /
braintwisting solutions to some problems, maybe not :)

David Vallner


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