Currently quasiquoting is limited to patterns and expressions, are there any problems in extending it to declarations? we already have [d| ... |] and toplevel splices afterall.
_______________________________________________ template-haskell mailing list template-haskell <at> haskell.org http://www.haskell.org/mailman/listinfo/template-haskell
I think there is no difficulty in principle.
In the HsExpr you’ll see the constructors
HsSpliceE
HsQuasiQuoteE
The former is run by the type checker; thelatter by the renamer.
To fulfil your hope, we’d need to add a new constructor to HsDecls.SpliceDecl. At the moment it just has
SpliceDecl
and we’d add
QuasiQuoteDecl
After that I think the rest would follow. If someone feels like taking it up, I’d be glad to help. For a start, make a Trac feature request and dump this thread into it.
Meanwhile, I gather you are using quasi-quotes. I’m interested to know about applications: what are you using it for?
Simon
From: template-haskell-bounces <at> haskell.org
[mailto:template-haskell-bounces <at> haskell.org] On Behalf Of Andrea
Vezzosi
Sent: 01 December 2008 08:15
To: template-haskell <at> haskell.org
Subject: [Template-haskell] QuasiQuoting for declarations
Currently quasiquoting is limited to patterns and expressions, are there any problems in extending it to declarations? we already have [d| ... |] and toplevel splices afterall.
_______________________________________________ template-haskell mailing list template-haskell <at> haskell.org http://www.haskell.org/mailman/listinfo/template-haskell
Simon Peyton-Jones wrote:
> Meanwhile, I gather you are using quasi-quotes. I’m interested
> to know about applications: what are you using it for?
(I assume this was a general query, hence my reply...)
I'm using it in testing... I have written an an interpreter for a (C-like) language, and quasi-quotation
makes the tests for the interpreter read very nicely -- I express a short program in the 'native' language
syntax (within a quasi-quotation), and then a few lines of Haskell defining the expected behavior of the
program. Without quasiquotation, I'd either have to store the 'native' programs in separate files or
build them up as strings (which means, in either case, I could get the syntax wrong and not know it until I run
the tests. And the tests are harder to read). It was close to zero work to create the quasi-quoter, since I
already had the parser handy. (I did have to enhance it to handle antiquotation, which I needed to make the
tests easier to write).
I've visions of using the same technique for expressing tests (queries and expected replies) in the native
syntax of a particular server I'm involved in developing, but have not done so yet.
Rob
On Tue, Dec 2, 2008 at 4:31 PM, Robert Greayer <robgreayer <at> yahoo.com> wrote: > Simon Peyton-Jones wrote: > >> Meanwhile, I gather you are using quasi-quotes. I'm interested >> to know about applications: what are you using it for? > > (I assume this was a general query, hence my reply...) > > I'm using it in testing... I have written an an interpreter for a (C-like) language, and quasi-quotation makes the tests for the interpreter read very nicely -- I express a short program in the 'native' language syntax (within a quasi-quotation), and then a few lines of Haskell defining the expected behavior of the program. Without quasiquotation, I'd either have to store the 'native' programs in separate files or build them up as strings (which means, in either case, I could get the syntax wrong and not know it until I run the tests. And the tests are harder to read). It was close to zero work to create the quasi-quoter, since I already had the parser handy. (I did have to enhance it to handle antiquotation, which I needed to make the tests easier to write). > > I've visions of using the same technique for expressing tests (queries and expected replies) in the native syntax of a particular server I'm involved in developing, but have not done so yet. > > Rob > > > > > _______________________________________________ > template-haskell mailing list > template-haskell <at> haskell.org > http://www.haskell.org/mailman/listinfo/template-haskell > I'm using quasiquoting to generate statically-sized vectors and matrices. The vectors and matrices are abstract datatypes, so quasiquoting gives a method for statically-checked construction, and also potentially allows more efficient construction than, say, converting to and from lists. Reiner
RSS Feed