dhall-1.26.0

• Supports version 10.0.0 of the standard
• BREAKING CHANGE TO THE LANGUAGE: Remove old union literal syntax
  • Union literals of the form < x = e | ... > are no longer valid
  • For more details, see: Migration: Deprecation of old union literal syntax
  • Also see the changelog for standard version 10.0.0 for more details
• BREAKING CHANGE TO THE API: Change X to be a type synonym for Data.Void
  • This is a breaking change if you were previously pattern matching on the
    X constructor. You can replace that with the use of Data.Void.absurd
• BREAKING CHANGE TO THE API: Treat multi-lets as syntactic sugar
  • This is a breaking change because the Let constructor now only stores
    one Binding instead of a NonEmpty list of Bindings
• PERFORMANCE REGRESSION & TECHNICALLY BREAKING CHANGE TO THE LANGUAGE: Dependent types
  • You can now write functions from terms to types
  • There is also now language support for tests of the form
    assert : x === y
  • This deteriorates the performance of large multi-let expressions
    (See: #1306)
  • Splitting large multi-let expressions into smaller files may mitigate
    the problem as a work-around for now
  • Follow #1129
    for work to fix this performance regression
  • This is also a technically breaking change because assert is now a
    reserved keyword
  • See the changelog for standard version 10.0.0 for more details
• TECHNICALLY BREAKING CHANGE TO THE LANGUAGE: Add Natural/subtract built-in
  • The language now supports machine subtraction, which can be used to
    support several other high-performance operations (like Natural
    comparisons)
  • This is a technically breaking change if you used Natural/subtract as an
    identifier in your code
  • See the changelog for standard version 10.0.0 for more details
• TECHNICALLY BREAKING CHANGE TO THE LANGUAGE: More simplifications for field selection
  • Now the interpreter will more intelligently simplify certain field
    projections
  • For example: λ(x : { a : Bool, b : Bool }) → (x ⫽ { c = 0 }).{ a, c }.c
    will now simplify to λ(x : { a : Bool, b : Bool }) → 0
  • This is a technically breaking change because you will need to update
    integrity checks that protect code simplified in this way
  • See the changelog for standard version 10.0.0 for more details
• TECHNICALLY BREAKING CHANGE TO THE LANGUAGE: Simplify ⫽ when its arguments are equivalent
  • This is a technically breaking change for the same reason: this will
    perturb semantic integrity checks for affected code
  • See the changelog for standard version 10.0.0 for more details
• NEW FEATURE: Restore support for records containing both types and terms
  • In other words { foo = 1, bar = Bool } is now valid again
  • This means that you now can export a single package containing both types
    and terms
  • See the changelog for standard version 10.0.0 for more details
• dhall format now preserves let comments
  • dhall format will now preserve comments in the following locations of
    a let binding:
  • let {- HERE -} x {- HERE -} : {- HERE -} Bool = {- HERE -} True in x
  • This support handles both single-line and multi-line comments and also
    takes care of correctly indenting/dedenting them
  • Note that comments before the let keyword are still not preserved
    (unless it is the beginning of the file)
• Add API support for marshalling recursive types
  • You can now marshal recursive types from Dhall into Haskell using the
    newly-added utilities
  • See also: #1298
• New :help command for dhall repl
• New --no-cache flag
  • You can now disable use of the cache with this flag
  • This comes in handy if you want to disable α-normalization for imports
    protected by a semantic integrity check
• Bug fixes
  • Fix isNormalized for field selections
  • Simplify Natural/subtract when its arguments are equivalent
  • Fix NaN to be judgmentally equivalent to itself
  • Fix Inject instance for lists
  • Fix typechecking of toMap
• Performance optimizations
  • Optimize a few Set instances
  • Remove some redundant sorting during normalization
• Improvements to error messages
  • Improve error reporting for failed remote imports
  • Improve HTTP errors
• Improvements to formatting
  • Indent function arguments when formatting
  • Prefer unquoted URLs
  • Strip leading whitespace
• Improvements to diffs
  • Fix diffs for lists
  • Improve diff for non-empty lists
  • Small fixes to dhall diff
• Improvements to documentation
  • Fix documentation for UnionInputType
  • Document support for caching protected imports
• Improvements to command-line interface
  • Improve description of dhall lint
  • Change dhall type to resolve imports