On 2016-09-30 07:25 PM, David Feuer wrote:
I've been playing around with the idea of writing Haskell 2010 type classes for finite sequences and non-empty sequences, somewhat similar to Michael Snoyman's Sequence class in mono-traversable. These are naturally based on Monoid1 and Semigroup1, which I think belong in base.
If the proposal is to add these directly to base, I'm against it. New classes should first be released in a regular package, and only moved to base once they prove useful.
class Semigroup1 f where (<<>>) :: f a -> f a -> f a class Semigroup1 f => Monoid1 f where mempty1 :: f a
Then I can write
class (Monoid1 t, Traversable t) => Sequence t where singleton :: a -> t a -- and other less-critical methods
class (Semigroup1 t, Traversable1 t) => NESequence where singleton1 :: a -> t a -- etc.