[Haskell-cafe] The applicative instances for Either?
R.Paterson at city.ac.uk
Sat Sep 17 12:21:55 CEST 2011
Ketil Malde writes:
> I have a program that makes use of the applicative instance for Either
> String. I used to define these instances locally, but at some point,
> they became part of Control.Applicative. I have limited the
> dependencies to 'base >= 4', but apparently, some version 4s of base
> include this instance, some do not, and it causes problems for people
> trying to compile the program.
> Is there any information, or otherwise accessible source specifying
> exactly when this was changed, so that I can have more precise
base is released with GHC, so the info is in the release notes for a
major GHC release (library interfaces aren't allowed to change in
* Version number 126.96.36.199 (was 188.8.131.52)
* There are now Applicative, Monad and MonadFix instances for Either.
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