[Haskell-beginners] No instance for Show arising from a use in “main” level
T. Andrea Moruno Rodriguez
tatiana.moruno at gmail.com
Wed Aug 24 00:44:04 UTC 2016
Thanks I resolved my problem. The explanation is here:
2016-08-23 20:23 GMT-04:00 Imants Cekusins <imantc at gmail.com>:
> Hello Tatiana,
> these signatures do not look good:
> main :: (Show (IO J2s)) => IO()
> test :: (Show (IO J2s)) => String -> IO()
> testParser :: (Show (IO J2s)) => IO()
> constraints are used to specify type variables. IO J2s looks like * (a
> fixed type).
> what errors do you see without these constraints?
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