v0.15.12

New features:

• Move the closed record update optimization (#4489 by @rhendric)

  For consumers of CoreFn like alternate backends, the optimization of
  replacing a closed record update with an object literal has now been moved to
  the point of desugaring CoreFn into JS. The ObjectUpdate expression
  constructor now contains a Maybe field holding a list of record labels to
  be copied as-is, for backends that want to perform this optimization also.

• Allow instances that require Fail to be empty (#4490 by @rhendric)

  A class instance declaration that has Prim.TypeError.Fail as a constraint
  will never be used. In light of this, such instances are now allowed to have
  empty bodies even if the class has members.

  (Such instances are still allowed to declare all of their members, and it is
  still an error to specify some but not all members.)

Bugfixes:

• Stop emitting warnings for wildcards in Visible Type Applications (#4492 by @JordanMartinez)

  Previously, the below usage of a wildcard (i.e. _) would
  incorrectly cause the compiler to emit a warning.

  f :: forall @a. a -> a
  f = identity
  
  x :: { x :: Int }
  x = f @{ x :: _ } { x: 42 }

• Infer types using VTA inside a record (#4501 by @JordanMartinez)

  Previously, use would fail to compile
  because the v type variable would not be inferred
  to String. Now the below code compiles:

  reflect :: forall @t v . Reflectable t v => v
  reflect = reflectType (Proxy @t)
  
  use :: String
  use = show { asdf: reflect @"asdf" }

Internal:

• Use gh for release artifacts (#4493 by @rhendric, #4509 by @JordanMartinez)

• Stop triggering CI on non-code-related changes (e.g. Readme) (#4502 by @JordanMartinez)