[Haskell-cafe] Troubles with HStringTemplate (compilation/runtime errors)

[Ilya Seleznev]

Yes! Importing GenericStandard() solved the problem! Thank you very much!
And big thanks for the HStringTemplate itself - awesome library!

On Sun, Jun 21, 2015 at 8:22 PM, S. Clover <s.clover at gmail.com> wrote:

> You probably also need to import Text.StringTemplate.GenericStandard to
> bring the instance for Data into scope. It was originally exported
> seperately to be compatible with either syb or syb-with-class. But
> syb-with-class is no longer supported because it did not come into
> widespread use. GenericStandard should probably be exported by default
> these days, especially since orphan instances are more frowned upon than
> when the package was written.
>
> -S
>
>
> On June 21, 2015 at 7:35:14 AM, Ilya Seleznev (itsuart at gmail.com) wrote:
> > Hello Haskellers,
> >
> > I hope I chose proper mailing list, if not I apologize. And thanks for
> > reading this!
> >
> > I run into a problem with HStringTemplate (
> > http://hackage.haskell.org/package/HStringTemplate) that I have never
> seen
> > before.
> > Code, similar to
> >
> > {-# LANGUAGE OverloadedStrings, DeriveDataTypeable, NoImplicitPrelude #-}
> > module Main where
> > import Data.Data
> > import qualified Data.Text as T
> > import qualified Text.StringTemplate as Template
> >
> > renderTextTemplate :: (Template.ToSElem a) => T.Text -> a -> IO T.Text
> > renderTextTemplate name input = do
> > templatesGroup <- Template.directoryGroup "templates"
> > case Template.getStringTemplate (T.unpack name) templatesGroup of
> > Nothing -> return $ "Internal Error: template '" `mappend` name
> > `mappend` "' can not be rendered"
> > Just template -> return $ Template.render (Template.setAttribute "it"
> > input (template:: Template.StringTemplate T.Text))
> >
> > data Foo = Foo {value:: T.Text} deriving (Data, Typeable)
> >
> > main :: IO ()
> > main = do
> > content <- renderTextTemplate "test" $ Foo {value = "oh hi there!"}
> > putStrLn content
> >
> > with a simple template like this:
> > Just a test $it.value$!
> >
> > started to cause complaints from GHC (7.8.2 and 7.8.4 on Linux x86_64):
> > No instance for (Template.ToSElem Foo)
> >
> > Problem is - it didn't do that before. What even more confusing, older
> > project[0] uses same approach, compiles (same machine, same compiler) and
> > works just fine!
> > I've exhausted all means to fix the problem that I could think off:
> > - Adding 'instance Template.ToSElem Foo' allows code to compile but it
> > doesn't work and prints message in console like this:
> > Main.hs:30:10-29: No instance nor default method for class operation
> > Text.StringTemplate.Classes.toSElem
> > - Tried to use same version of HStringTemplate deps (syb was different)
> > - All kinds of desperate messing around (exporting records from modules,
> > changing field names...)
> > - Updated ghc from 7.8.2 to 7.8.4
> > - Googled error messages
> > to no avail.
> >
> > I hope almighty All would give me some ideas/directions because I have
> none
> > left.
> >
> > [0] Function:
> >
> https://github.com/itsuart/fdc_archivist/blob/master/src/HttpUtils.hs#L59
> > Data:
> >
> https://github.com/itsuart/fdc_archivist/blob/master/src/ViewModels/HomeViewModel.hs
> > Usage:
> >
> https://github.com/itsuart/fdc_archivist/blob/master/src/HomeViewFeature.hs#L59
> > --
> > With best regards,
> > Ilya Seleznev
> > _______________________________________________
> > Haskell-Cafe mailing list
> > Haskell-Cafe at haskell.org
> > http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe
> >
>
>


-- 
With best regards,
Ilya Seleznev
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