v17.0.0

Breaking changes:

• Remove the ability to quote paths in URLs

  After a deprecation period, quoted path components are no longer supported in
  URLs. For example, this is no longer valid:

  https://example.com/"foo bar"

  Instead, you will now need to percent-encode path components:

  https://example.com/foo%20bar

  For more details, see: Deprecation of quoted paths in URLs

• Remove Optional/build and Optional/fold

  After a deprecation period, Optional/build and Optional/fold are no longer
  built-ins and can be implemented in terms of other language constructs.

  Specifically, Optional/build can be replaced with Prelude.Optional.build,
  which is defined as:

  λ(a : Type) →
  λ ( build
    : ∀(optional : Type) → ∀(some : a → optional) → ∀(none : optional) → optional
    ) →
    build (Optional a) (λ(x : a) → Some x) (None a)

  ... and Optional/fold can be replaced with Prelude.Optional.fold, which is
  defined as:

  λ(a : Type) →
  λ(o : Optional a) →
  λ(optional : Type) →
  λ(some : a → optional) →
  λ(none : optional) →
    merge { None = none, Some = some } o

  For more details, see: Deprecation of Optional/fold and Optional/build

New features:

• Allow quoted labels to be empty

  You can now define records with blank labels, so long as you escape them with
  backticks, like this:

  { `` = 1 }

• Fixes and improvements to the Prelude:

  • Add Prelude/List/unpackOptional
  • Fix List/zip
  • Prelude: Reduce cache size of JSON rendering code

Other changes:

• Fixes and improvements to the standard:

  • Not all ABNF parsers like empty rules
  • Ensure keyword rule only matches keywords
  • Remove Unicode character from dhall.abnf

• Fixes and improvements to the standard test suite:

  • Test that we typecheck let annotations
  • Add keyword record fields failure tests