[Haskell-cafe] Store type-class polymorphic values generically

[Christopher Done]

On 4 October 2013 10:56, Heinrich Apfelmus <apfelmus at quantentunnel.de> wrote:
> In particular, the  Locker  stores arbitrary values like  Dynamic , except
> that values are extracted and removed with the help of a  Key . This gets
> rid of the  Typeable  constraint.

lock :: Key a -> a -> Locker

I can't pass anything with class constraints to that.