Amulet 0.4.2.0 "<!-- Squid: fill in this joke -->"

Changes since last release:

• Check for orphan instances, closing a soundness hole #191
• “Quick Look” impredicative polymorphism, #203

The new thing: QL Impredicativity

"Quick Look" impredicativity extends Amulet's support for first-class polymorphism. Like any implementation of this, it's dubiously useful, but does still allow writing some pretty neat snippets, such as constructing a list of identity functions:

let ids : list (forall 'a. 'a -> 'a) =
  let empty : list (forall 'a. 'a -> 'a) = []
  (fun x -> x) :: empty

You can get this release here or through the usual means.