[Haskell-cafe] Re: Nano-Languages

Vladimir Zlatanov vlado at dikini.net
Thu Dec 10 13:04:34 EST 2009

I'll try to paraphrase you, to see if I understand you correctly.

The  composition splice . quote can have one 'hard' error source.
Grammatically incorrect quote. I think that will be caught by the type
checker. Of a bigger concern are logical errors, introduced by buggy
macros. But it is template haskell, so the same rules and tools apply.

What I suggest is replacing the $x of template haskell, with S.x,
where S is a module imported for syntax. What I'm not sure is how to
deal with matching$(...). I'm not sure that the parenthesis can be
avoided in all cases.

On Thu, Dec 10, 2009 at 4:59 PM, John D. Earle <JohnDEarle at cox.net> wrote:
> Vladimir, I do not mind becoming more familiar with the internals, but as
> you pointed out that Template Haskell may provided much of the needed
> functionality. I tend to doubt that it will provide all the needed
> functionality, however. The new syntax created by the syntax macros will
> either reinterpret a preexisting production in the language or will create a
> new one which may be based on a preexisting production, a variant. In the
> latter case, the compiler will have a knee jerk reaction. It will feel that
> the structure is grammatically illegal! This knee jerk would need to be
> intercepted and assigned an interpretation. We would then need to calm the
> compiler down and say its ok.
> --------------------------------------------------
> From: "Vladimir Zlatanov" <vlado at dikini.net>
> Sent: 10 Thursday December 2009 0854
> To: "Haskell Cafe" <haskell-cafe at haskell.org>
> Subject: Re: [Haskell-cafe] Re: Nano-Languages
>>> If one were to think of this as a project, the initial project goal might
>>> be
>>> a proof of concept, that such an undertaking though non-trivial may be
>>> worth
>>> while.
>> for me it is currently quite tough, since I don't know the internals at
>> all
>>> It would be desirable to act on the abstract syntax trees that result
>>> from
>>> the compiler parsing the source code and not the source code itself.
>> Template Haskell does that - it provides quotations, quasi-quotations
>> and splicing, along with other utilities.
>> I would guess that a simple design would be to add an import_syntax
>> clause, similar to import, but importing only declarations with type
>> ...-> Q ... and splicing automatically their appearances.
>> This is a back of the envelope design, and I haven't considered any
>> potential side-effects, but sounds like a reasonable approach
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