[Haskell-beginners] special polymorphic default of typeclass depending on other typeclasses?

[Jean Lopes]

It appear more like Show, you can add a  constraint to the generic instance

instance Show a => Foo a where
    bar x = show x




Em 29 de jun de 2017 2:16 PM, "Silent Leaf" <silent.leaf0 at gmail.com>
escreveu:

hi,

say i have the following typeclass:

class Foo a where
  bar :: a  -> String

looks a lot like the Read typeclass, right? (at least i think it should?)
well say it's a different meaning (in other terms i can't or do not want to
use Read, but i'd like to implement a default version of bar for those
instances that also implement Read. is there a way to do so?

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