Solutions to Typeclassopedia Ex. 3.3.1?

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David Banas

27 Sep 2015 27 Sep '15

10:33 a.m.

Would anyone care to share their solution to exercise 3.3.1 in Typeclassopedia? Thanks, -db

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Sumit Sahrawat, Maths & Computing, IIT (BHU)

27 Sep 27 Sep

10:52 a.m.

The holy source :) https://hackage.haskell.org/package/base-4.8.1.0/docs/src/GHC.Base.html#line... https://hackage.haskell.org/package/base-4.8.1.0/docs/src/Data.Either.html#l... On 27 September 2015 at 20:03, David Banas wrote:

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Would anyone care to share their solution to exercise 3.3.1 in *Typeclassopedia*?

Thanks, -db

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-- Regards Sumit Sahrawat

Francesco Ariis

11:11 a.m.

On Sun, Sep 27, 2015 at 08:22:55PM +0530, Sumit Sahrawat, Maths & Computing, IIT (BHU) wrote:

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The holy source :)

https://hackage.haskell.org/package/base-4.8.1.0/docs/src/GHC.Base.html#line...

https://hackage.haskell.org/package/base-4.8.1.0/docs/src/Data.Either.html#l...

instance Functor (Either a) where fmap _ (Left x) = Left x fmap f (Right y) = Right (f y) `fmap id = id` and `fmap (f . g) = fmap f . fmap g` seem to hold here, no?