[Haskell-beginners] applicativeParsec.hs in Real World Haskell not compiling any more
k.bleijenberg at inter.nl.net
Thu Oct 25 10:46:39 CEST 2012
Hum, the current version is 7.6.1, you should consider installing that,
7.0.4 is already rather oldish.
I don't know what the latest version is for Windows. I'll give it a try.
> unchanged version doesn't compile any more. I get warning:
> Illegal instance declaration for `Applicative (GenParser s a)'
> (All instance types must be of the form (T t1 ... tn)
> where T is not a synonym.
> Use -XTypeSynonymInstances if you want to disable this.)
> In the instance declaration for `Applicative (GenParser s a)'
> Illegal instance declaration for `Alternative ....(same advice as
That's unfortunate, it should better have reported the below immediately.
But it's hard to make the compiler always give the best error message, so
sometimes it gives a not-best.
> Then I added the OverlappingInstances directive. Same error and no
> I wonder, is this the new GHC version? And what can I do about it?
It's a new parsec version, that now provides Applicative and Alternative
Just remove (delete or comment out) the instance declarations from your
--- end original message
Removing ApplicationParsec.hs from the project and adding a few new
references (Control.Applicative....) did the trick.
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