wiki:QuantifiedContexts

Quantified contexts

This wiki page summarises the state of play on the idea of allowing quantification in class contexts. For example

data Rose f a = Branch a (f (Rose f a))

instance (Eq a, forall b. (Eq b) => Eq (f b))
       => Eq (Rose f a)
  where ...

The new bit is the forall in the context of the instance declaration.

Here are some resources

  • #2893, a ticket about the idea

Status

Use Keyword = QuantifiedContexts to ensure that a ticket ends up on these lists.

Open Tickets:

#2893
Implement "Quantified contexts" proposal
#8516
Add (->) representation and the Invariant class to GHC.Generics
#9123
Need for higher kinded roles
#13153
Several Traversable instances have an extra fmap
#14070
Allow ‘unsafe’ deriving strategy, deriving code with ‘unsafeCoerce’
#14317
Solve Coercible constraints over type constructors

Closed Tickets: No results

Last modified 4 months ago Last modified on Aug 1, 2017 3:53:31 PM