[Haskell-cafe] Type checking the content of a string

[Corentin Dupont]

Finally, I solved the problem using typeOf instead of interpret:

cr :: QuasiQuoter
cr = QuasiQuoter { quoteExp = quoteRuleFunc}

quoteRuleFunc :: String -> Q TH.Exp
quoteRuleFunc s = do
   res <- runIO $ runInterpreter $ do
      setImports ["Prelude", "Language.Nomyx.Expression"]
      typeOf s
   case res of
      Right "RuleFunc" -> [| s |]
      Right _ -> fail $ "Rule doesn't typecheck"
      Left e -> fail $ show e

I don't know really why, but now it's working very well!

On Sat, Feb 23, 2013 at 7:56 PM, Daniel Gorín <jcpetruzza at gmail.com> wrote:

> Hi Corentin,
>
> I've never used TH, but from what I understand, trying to combine hint and
> TH would be redundant (even if it worked): whatever String you can evaluate
> using hint, you can evaluate it directly in TH. Is this not the case?
>
>  Cheers,
> Daniel
>
> On Feb 23, 2013, at 6:53 PM, Corentin Dupont wrote:
>
> > Hi Daniel,
> > Did you already tried to use Hint in a QuasiQuote? This would come handy
> to check at compile time the validity of some strings...
> > However I have the error hereunder.
> > The duplicate symbol found in the object file is in fact the first
> symbol in this file. So I guess GHCi tries to load it twice...
> > Best,
> > Corentin
> >
> >
> > On Sat, Feb 23, 2013 at 12:03 AM, Corentin Dupont <
> corentin.dupont at gmail.com> wrote:
> > I'm trying to load my interpreter in the Q monad:
> >
> > cr :: QuasiQuoter
> > cr = QuasiQuoter { quoteExp = quoteRuleFunc}
> >
> > quoteRuleFunc :: String -> Q TH.Exp
> > quoteRuleFunc s = do
> >    res <- runIO $ runInterpreter $ do
> >       setImports ["Prelude", "Language.Nomyx.Rule",
> "Language.Nomyx.Expression", "Language.Nomyx.Test",
> >                "Language.Nomyx.Examples", "GHC.Base", "Data.Maybe"]
> >       interpret s (as :: RuleFunc)
> >    case res of
> >       Right _ -> [| s |]
> >       Left e -> fail $ show e
> >
> >
> >  However, I always obtain an error during compilation:
> >
> > ...
> > Loading package XXX ... linking ... done.
> >
> >
> > GHCi runtime linker: fatal error: I found a duplicate definition for
> symbol
> >    __stginit_ghczm7zi4zi1_DsMeta
> > whilst processing object file
> >    /usr/lib/ghc/ghc-7.4.1/libHSghc-7.4.1.a
> > This could be caused by:
> >    * Loading two different object files which export the same symbol
> >    * Specifying the same object file twice on the GHCi command line
> >    * An incorrect `package.conf' entry, causing some object to be
> >      loaded twice.
> > GHCi cannot safely continue in this situation.  Exiting now.  Sorry.
> >
> >
> > I vaguely understand that the interpreted modules are conflicting with
> the compiled ones...
> >
> >
> >
> > On Fri, Feb 22, 2013 at 11:51 PM, Corentin Dupont <
> corentin.dupont at gmail.com> wrote:
> > Great! That seems very powerful. So you can do what you want during
> compilation, readin files, send data over the network?
> > Other question, in my example how can I halt the compilation if a test
> program is wrong?
> >
> >
> > On Fri, Feb 22, 2013 at 8:30 PM, Francesco Mazzoli <f at mazzo.li> wrote:
> > At Fri, 22 Feb 2013 19:43:51 +0100,
> > Corentin Dupont wrote:
> > > Hi Adam,
> > > that looks interresting. I'm totally new to TH and QuasiQuotes, though.
> > > Can I run IO in a QuasiQuoter? I can run my own interpreter.
> >
> > Yes, you can:
> > <
> http://hackage.haskell.org/packages/archive/template-haskell/2.8.0.0/doc/html/Language-Haskell-TH.html#v:runIO
> >.
> >
> > Francesco
> >
> >
> >
>
>
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