[erlang-questions] comma-less lists and tuples

Vlad Dumitrescu <>
Thu Sep 21 12:38:09 CEST 2006


On 9/21/06, Ulf Wiger (TN/EAB) <> wrote:
> Vlad Dumitrescu wrote:
> > How could the Erlang compiler help me write better SQL
> > statements? Yes, if I write quasi-SQL, I get some syntax
> > checking, but I still can write stupid things like
> >     {select, {where, {x, '=', 3}}, foo, {from, [table]}}
> > which is a correct Erlang term, but not correct quasi-SQL.
> Well, that would be the task of a domain-specific parser,
> or a parse_transform.

Yes, of course. This is what I was trying to say too, but didn't
manage to express my self as clearly.

> Departing from Erlang syntax is tricky in a parse transform,
> since the erlang tokenizer and parser will get hold of it
> before your parse transform.

This might get a solution, "Quite Soon (tm)"-ish.

> A MSc student did write an SQL parser converting SQL
> to Mnemosyne queries. This worked quite well. Going
> from a QLC query to SQL should be doable, and - assuming
> I'm right - raises the argument that Erlang already
> _has_ quite a powerful syntax for database queries.
> So why invent a new one?

Very good point. But this wouldn't make the discussion obsolete
because there might be other DSLs that one might want to use besides
sql.

best regards,
Vlad



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