On 12/10/2011 09:38, Iustin Pop wrote: > On Fri, Dec 09, 2011 at 10:30:18PM +0100, L Corbijn wrote: >> The major set of problems for using template haskell is that it >> doesn't have the correct features, or better said it tries to solve >> another problem. Template haskell generates code into an existing >> module, while for this problem there is no module yet to generate it >> into. Of course I could generate those modules and let template >> haskell make the FFI imports, but then the problem remains how to >> generate those modules. So template haskell seems (as I see it) to >> solve the problem of writing almost the same code twice by generating >> it from some parameters coded in some source file. Another problem is >> that the export and import lists of the modules need to be generated >> too and this seems not an option for TH. > > On Fri, Dec 09, 2011 at 04:27:31PM -0600, Antoine Latter wrote: >> For my case, template haskell can't create modules, and template >> haskell solves a different problem - I've not interested in creating >> Haskell declarations from Haskell declarations - I'm interested in >> creating Haskell modules from an external, formal, specification. In >> a sense I'm compiling to Haskell. > > This answer is for both the above quotes. While TH is not perfect (and > sometimes tedious/difficult to write in), it's not restricted to simply > generate code based on some parameters in an existing Haskell file. > > It cannot generate modules, true, but other than that you could have a > module simply like this: > > module Foo where > > import … > > $(myBuilder) > > Where myBuilder doesn't take any parameters, just reads some external > (XML, text file, whatever) and build the code from scratch. > > I might misunderstand the problem, but I think that you _could_ use TH > for "compiling" to Haskell, as long as you have a Haskell parser for the > external/formal spec. > > regards, > iustin
There are the haskell-src-exts-qq and haskell-src-meta packages on hackage that will get you partway to generating source code for a Haskell module. Full support for Haskell quasiquotation would require a modified version of haskell-src-exts (to properly handle antiquotation). The problem with TH is that it runs when the module is compiled. Reading a spec in from a file within a TH quote is possible, but it would be much nicer to be able to write a code generator, which a full Haskell quasiquoter would allow. Maybe someone is interested in a side-project? :) Geoff _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
