[Haskell-cafe] On to applicative

[michael rice]

Thanks, Brandon.

Michael

--- On Sat, 8/28/10, Brandon S Allbery KF8NH <allbery at ece.cmu.edu> wrote:

From: Brandon S Allbery KF8NH <allbery at ece.cmu.edu>
Subject: Re: [Haskell-cafe] On to applicative
To: "michael rice" <nowgate at yahoo.com>
Cc: haskell-cafe at haskell.org
Date: Saturday, August 28, 2010, 10:43 PM

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On 8/28/10 22:15 , michael rice wrote:
> Prelude> fmap (*2) l
> 
> <interactive>:1:0:
>     No instance for (Functor (Either Integer))
>       arising from a use of `fmap' at <interactive>:1:0-10
>     Possible fix:
>       add an instance declaration for (Functor (Either Integer))
>     In the expression: fmap (* 2) l
>     In the definition of `it': it = fmap (* 2) l
> Prelude>

Huh.  I understood it to be defined in the Prelude, but didn't check.

Looks like it's now in Control.Monad.Instances (a relatively new module).
Confusing....

- -- 
brandon s. allbery     [linux,solaris,freebsd,perl]      allbery at kf8nh.com
system administrator  [openafs,heimdal,too many hats]  allbery at ece.cmu.edu
electrical and computer engineering, carnegie mellon university      KF8NH
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