[Haskell-cafe] Haddock: Documentation of instances with
un-documentable type arguments
Ivan Lazar Miljenovic
ivan.miljenovic at gmail.com
Sat Sep 4 06:03:00 EDT 2010
On 4 September 2010 19:01, Alexander McPhail
<haskell.vivian.mcphail at gmail.com> wrote:
> Hi
>
> Is there a similar ticket for GHC to not export instances in the case that
> other instances are explicitly specified?
>
> module Foo (
> Foo(Monad)
> )
>
> instance Monad Foo where ...
> instance MonadState (Foo Bar) where ...
>
> i.e. the monad instance gets exported but the MonadState one does not? This
> helps in maintaining opacity with respect to the package user. I may not
> want the user to be able to call 'get' and 'put' when using my custom monad.
No: instances are implicitly imported and exported (if the class and
the type are visible, then so are any possible instances).
--
Ivan Lazar Miljenovic
Ivan.Miljenovic at gmail.com
IvanMiljenovic.wordpress.com
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