Changelog for dhall-1.26.0

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 are no longer valid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

1.25.0

Supports version 9.0.0 of the standard
- See: https://github.com/dhall-lang/dhall-lang/releases/tag/v9.0.0
BREAKING CHANGE: Remove support for old-style List-like Optional literals
- List-like Optional Literals (i.e. [ 1 ] : Optional Natural) are no longer valid
- See: https://github.com/dhall-lang/dhall-haskell/pull/1002
BREAKING CHANGE: Add support for semi-semantic caching
- This change significantly improves the performance of imports
- This change also automatically caches imports without an integrity check
- This changes several types in Dhall.Import to support this new feature
- See: https://github.com/dhall-lang/dhall-haskell/pull/1113
BREAKING CHANGE: Implement new Unicode braced escape sequence
- Escape sequences encoding surrogate pairs are no longer valid
- Instead, characters previously encoded as surrogate pairs can instead be encoded as a braced sequence
- For example: "\uD834\uDD1E" must now be written as "\u{1D11E}"
- See: https://github.com/dhall-lang/dhall-haskell/pull/987
- See: https://github.com/dhall-lang/dhall-haskell/pull/1104
BREAKING CHANGE: Make the type of extract richer:
- Dhall.extract can now return a detailed error instead of just a Maybe
- This is a breaking chnage because the type of extract changed
- See: https://github.com/dhall-lang/dhall-haskell/pull/1011
BREAKING CHANGE: Add support for importing expressions as Location
- This is a breaking change because a new Location constructor was added to ImportMode
- See: https://github.com/dhall-lang/dhall-haskell/pull/1019
BREAKING CHANGE: Switch Var to use an Int
- This is a performance improvement, but also a breaking change since the Integer in the Var constructor was changed to an Int
- See: https://github.com/dhall-lang/dhall-haskell/pull/1044
BREAKING CHANGE: Add new toMap keyword
- This is a breaking change to the API because a new ToMap constructor was added to the Expr type
- This is also a technically breaking change to the language because toMap is now a reserved keyword, although most code should be unaffected in practice
- See: https://github.com/dhall-lang/dhall-haskell/pull/1041
BREAKING CHANGE: Sort the fields of a record projection during normalization
- This is a technically breaking change to the language because any expressions with an uninterpreted record projection will have a different semantic integrity check. However, most could should be unaffected in practice
- See: https://github.com/dhall-lang/dhall-haskell/pull/1111
BUG FIX: Fix substitution into record projection by type
- An expression like this one was being incorrectly rejected: let e = { a = 10, b = "Text" } let s = { a : Natural } in e.(s), which this change fixes
- See: https://github.com/dhall-lang/dhall-haskell/pull/1012
BUG FIX: Reject record projection when there is a field type mismatch
- Record projection by type was previously not checking the expected field types, which this change fixes
- See: https://github.com/dhall-lang/dhall-haskell/pull/1027
BUG FIX: Fix linting of unused let bindings
- Certain let bindings were not correctly detected as unused, which this change fixes
- See: https://github.com/dhall-lang/dhall-haskell/pull/1001
BUG FIX: Fix --file option
- The --file option from the previous release did not work, due to not computing relative paths correctly, which this change fixes
- See: https://github.com/dhall-lang/dhall-haskell/pull/1004
BUG FIX: Minor fix to dhall diff
- dhall diff was incorrectly displaying spurious differences for identical lists that were function arguments, which this change fixes
- See: https://github.com/dhall-lang/dhall-haskell/pull/1006
BUG FIX: Allow Sort as type annotation
- This should have been implemented in the previous release as part of supporting version 8.0.0 of the standard, but was missed
- See: https://github.com/dhall-lang/dhall-haskell/pull/1024
BUG FIX: Dhall.Map: Reflect original key ordering in Ord instance
- Dhall.Map now considers key order when comparing Maps, which it should have done before, but didn't
- See: https://github.com/dhall-lang/dhall-haskell/pull/1050
BUG FIX: Consistently format multi-line strings
- The formatter now formats naked multi-line strings the same as nested multi-line strings
- Specifically, naked multi-line strings can now be formatted on a single (just like nested multi-line strings)
- See: https://github.com/dhall-lang/dhall-haskell/pull/1056
BUG FIX: Make isNormalized consistent with normalize
- See: https://github.com/dhall-lang/dhall-haskell/pull/1115
BUG FIX: Make normalizeWithM consistent with normalize
- See: https://github.com/dhall-lang/dhall-haskell/pull/1126
BUG FIX: Fix import alternatives to recover from type errors
- See: https://github.com/dhall-lang/dhall-haskell/pull/1152
Feature: Semi-semantic caching
- The Haskell implementation now implicitly caches all local imports, not just imports frozen by integrity checks, so that you don't have to freeze them when doing local development
- These cached imports are still correctly invalidated if they or any of their dependencies change
- This new implicit cache is stored underneath ~/.cache/dhall-haskell by default
- See: https://github.com/dhall-lang/dhall-haskell/pull/1154
Feature: New dhall text subcommand
- This new subcommand supersedes the old dhall-to-text executable
Feature: Add instance Lift (Expr s a)
- See: https://github.com/dhall-lang/dhall-haskell/pull/1119
Fixes and improvements to error messages:
- See: https://github.com/dhall-lang/dhall-haskell/pull/1030
- See: https://github.com/dhall-lang/dhall-haskell/pull/1137
Fixes and improvements to tests:
- See: https://github.com/dhall-lang/dhall-haskell/pull/1155
- See: https://github.com/dhall-lang/dhall-haskell/pull/1159
Performance improvements
- See: https://github.com/dhall-lang/dhall-haskell/pull/1036
- See: https://github.com/dhall-lang/dhall-haskell/pull/1051
- See: https://github.com/dhall-lang/dhall-haskell/pull/1048
- See: https://github.com/dhall-lang/dhall-haskell/pull/1057
- See: https://github.com/dhall-lang/dhall-haskell/pull/1065
- See: https://github.com/dhall-lang/dhall-haskell/pull/1066
- See: https://github.com/dhall-lang/dhall-haskell/pull/1085

1.24.0

Supports version 8.0.0 of the standard
- See: https://github.com/dhall-lang/dhall-lang/releases/tag/v8.0.0
BREAKING CHANGE: Allow tabs and blank lines in multi-line strings
- Blank lines are now ignored for the purpose of dedenting multiline strings
- Lines with leading tabs (or mixed tabs and spaces) are now dedented, too, so long as they all share the same prefix
- This is technically a breaking change, but unlikely to affect programs in practice, especially if they were formatted with dhall format. This change mainly affects programs that were not indented correctly.
- See the changelog for standard version 8.0.0 for more details
BREAKING CHANGE: Simplify bare interpolations
- Expressions like λ(x : Text) → "${x}" now simplify to λ(x : Text) → x
- This is a technically breaking change because it changes how these sorts of expressions are serialized. This does not affect semantic integrity checks and the new simplified expressions are extensionally equivalent to their older counterpart expressions.
- See the changelog for standard version 8.0.0 for more details
BREAKING CHANGE: Encode integrity check as multihash
- Semantic integrity checks are now encoded using the multihash spec
- This is a technically breaking change that does not perturb the hash for user-facing semantic integrity checks. This only affects how expressions with unresolved imports are serialized, but semantic integrity checks are only computed for fully-resolved imports.
- See the changelog for standard version 8.0.0 for more details
BUG FIX: Fix type-checker to reject invalid record type annotations
- e.g. { x = 1 } : { x : Text } was not properly rejected by the type checker
- See: https://github.com/dhall-lang/dhall-haskell/pull/965
BUG FIX: Custom header forwarding fixed
- Forwarding custom headers could previously fail in various ways, such as:
  - Cyclic imports leading to endless network requests
  - Resolving a non-existent import for the custom headers
  - Resolving an existing but incorrect import for the custom headers
- This change fixes that by forwarding custom headers by value instead of by reference
- See: https://github.com/dhall-lang/dhall-haskell/pull/967
BUG FIX: Fix GHCJS support
- Natural/fold was broken in version 1.22, which this change fixes
- Specifically, it would hang for Natural numbers greater than 1
- See: https://github.com/dhall-lang/dhall-haskell/pull/985
BUG FIX: dhall diff no longer double-prints key-value separators
- See: https://github.com/dhall-lang/dhall-haskell/pull/952
Feature: Record projection by expression
- You can now project out a subset of record fields by the expected type
- let t = { x : Natural } let p = { x = 1, y = 2 } in p.(t) = { x = 1 }
- See the changelog for standard version 8.0.0 for more details
Feature: Inline headers
- You no longer need to specify custom headers in a separate import. You can now specify them inline within the same file.
- e.g.: https://example.com/x using [ { header = "Foo", value = "Bar" } ]
- See the changelog for standard version 8.0.0 for more details
Feature: Allow Sort as a type annotation
- An expression such as Kind → Kind : Sort will now type-check
- Sort is still disallowed outside of a type annotation
- See the changelog for standard version 8.0.0 for more details
Feature: Allow self-describe-cbor when decoding
- Dhall expressions serialized as CBOR can be tagged to describe themselves as CBOR without affecting decoding
- See the changelog for standard version 8.0.0 for more details
Feature: New --file option for dhall commands
- In other words, instead of dhall <<< './some/file you can now use dhall --file some/file
- See: https://github.com/dhall-lang/dhall-haskell/pull/949
Feature: New --cache flag for dhall freeze command
- This automates the idiom used by the Prelude to optimistically cache imports but gracefully degrade if the semantic integrity check fails
- See: https://github.com/dhall-lang/dhall-haskell/pull/980
Feature: Add :clear command to dhall repl
- This deletes previous bindings from the history so that they can be garbage collected
- See: https://github.com/dhall-lang/dhall-haskell/pull/966
Feature: New chunkExprs Traversal added to Dhall.Core
- See: https://github.com/dhall-lang/dhall-haskell/pull/954
Feature: New Dhall.Optics module
- This re-exports some convenient @lens@ utilities used internally for packages trying to avoid a @lens@ dependency
- See: https://github.com/dhall-lang/dhall-haskell/pull/986
More GHC 8.8 support
- See: https://github.com/dhall-lang/dhall-haskell/pull/961

1.23.0

BREAKING CHANGE: Fix marshaling union literals
- 1.22.0 introduced two separate bugs in marshaling union literals between Dhall and Haskell, which this release fixes:
  - Dhall enums did not correctly map onto Haskell enums
  - New-style union literals (i.e. < A : T >.A x) were not correctly supported
- See: https://github.com/dhall-lang/dhall-haskell/pull/918
- See: https://github.com/dhall-lang/dhall-haskell/pull/927
- See: https://github.com/dhall-lang/dhall-haskell/pull/936
BUG FIX: Fix α-normalization
- Version 1.22.0 introduced a new faster evaluation algorithm, but the new algorithm introduced two α-normalization regression, which this release fixes
- The primary effect of this bug was that semantic integrity checks would fail for expressions that contain an if/then/else` expression in their normal form
- See: https://github.com/dhall-lang/dhall-haskell/pull/931
- See: https://github.com/dhall-lang/dhall-haskell/pull/938
BUG FIX: Fix merging of sort-level record types
- The language standard requires that { a : Kind } ⩓ { b : Kind } is valid, which this change fixes
- See: https://github.com/dhall-lang/dhall-haskell/pull/891
BUG FIX: dhall freeze respects the --ascii flag
- See: https://github.com/dhall-lang/dhall-haskell/pull/934
BUG FIX: Don't autocomplete fields for record types
- This prevents the REPL from expanding { x : T }.<TAB> to { x : T }.x
- See: https://github.com/dhall-lang/dhall-haskell/pull/937
Support MonadFail-related changes in GHC 8.8
- See: https://github.com/dhall-lang/dhall-haskell/pull/912
Add cross flag to simplify cross-compilation
- This allows the dhall package to be built without using TemplateHaskell
- See: https://github.com/dhall-lang/dhall-haskell/pull/928
Increase lines of context for error messages
- Error messages now provide at least 20 lines of context instead of 3 before truncating large expressions
- See: https://github.com/dhall-lang/dhall-haskell/pull/916
Add line numbers to error messages
- The bottom of every Dhall type error includes the original source code, which now has line numbers on the left margin
- See: https://github.com/dhall-lang/dhall-haskell/pull/919
Expand lower bounds on megaparsec/transformers-compat dependencies
- This is to support dhall on Debian Sid
- See: https://github.com/dhall-lang/dhall-haskell/pull/939

1.22.0

Supports version 7.0.0 of the standard
- See: https://github.com/dhall-lang/dhall-lang/releases/tag/v7.0.0
BREAKING CHANGE: Add support for empty alternatives
- The Union type now has an optional (Maybe) type for each alternative
- See the changelog for standard version 7.0.0 for more details
- See: https://github.com/dhall-lang/dhall-haskell/pull/863
BREAKING CHANGE: Remove support for URL fragments
- The URL type no longer has a field for a URL fragment since the language no longer supports fragments
- See the changelog for standard version 7.0.0 for more details
- See: https://github.com/dhall-lang/dhall-haskell/pull/851
BREAKING CHANGE: Remove deprecated Path type synonym
- See: https://github.com/dhall-lang/dhall-haskell/pull/858
BUG FIX: Correctly parse identifiers beginning with http
- i.e. httpPort was supposed to be a valid identifier name and now is
- See: https://github.com/dhall-lang/dhall-haskell/pull/870
BUG FIX: Fix dhall encode bug
- dhall encode bug was generating binary expressions that were valid (i.e. they would decode correctly) but were non-standard (i.e. hashing them would not match the hash you would normally get from a semantic integrity check)
- Semantic integrity checks were not affected by this bug since they used a slightly different code path that generated the correct binary input to the hash. Only the dhall decode subcommand was affected
- See: https://github.com/dhall-lang/dhall-haskell/pull/859
BUG FIX: Fix for Dhall.UnionType
- This fixes some expressions that would previously fail to marshal into Haskell, specifically those were the marshalling logic was built using the UnionType utilities
- See: https://github.com/dhall-lang/dhall-haskell/pull/857
Feature: New --alpha flag to α-normalize command-line output
- See: https://github.com/dhall-lang/dhall-haskell/pull/855
Performance improvements
- The normalizer is now much faster
- See: https://github.com/dhall-lang/dhall-haskell/pull/876

1.21.0

Supports version 6.0.0 of the language standard
- See: https://github.com/dhall-lang/dhall-lang/releases/tag/v6.0.0
BREAKING CHANGE: Remove the constructors keyword
- ... as standardized in version 6.0.0 of the language standard
- The deprecation cycle is over, so the keyword is no longer supported
- For more details, see: https://github.com/dhall-lang/dhall-lang/wiki/Migration%3A-Deprecation-of-constructors-keyword
- See: https://github.com/dhall-lang/dhall-haskell/pull/829
BREAKING CHANGE: CBOR-encode only special Doubles as half-floats
- ... as standardized in version 6.0.0 of the language standard
- CBOR Doubles except Infinity/-Infinity/NaN/0.0 are now encoded in at least 32 bits
- See: https://github.com/dhall-lang/dhall-haskell/pull/822
BREAKING CHANGE: Sort record and union fields when CBOR-encoding
- Fields and alternatives are now sorted when serialized
- This does not affect semantic integrity checks, which already sorted these fields/alternatives before hashing expressions
- This does affect the serialization of expressions that have not been normalized (e.g. uninterpreted expressions transmitted over the wire)
- See: https://github.com/dhall-lang/dhall-haskell/pull/835
BUG FIX: Fix non-exhaustive pattern match in dhall lint
- This fixes: Irrefutable pattern failed for pattern Let (l' :| ls') d'
- This bug would cause dhall lint to fail on some nested let/in expressions
- See: https://github.com/dhall-lang/dhall-haskell/pull/780
- See: https://github.com/dhall-lang/dhall-haskell/pull/784
BUG FIX: Don't fail if $HOME environment variable is unset
- The interpreter was incorrectly throwing an exception if HOME was unset
- The standard requires that implementations should handle the HOME environment variable being missing
- See: https://github.com/dhall-lang/dhall-haskell/pull/789
Feature: Remove version tag from semantic integrity check
- ... as standardized in version 6.0.0 of the language standard
- This is not a breaking change because this change also includes backwards-compatible support for semantic integrity checks produced by older versions of the interpreter
Feature: Support Unicode path components
- ... as standardized in version 6.0.0 of the language standard
- You can now use Unicode in path components if they are quoted
- i.e. ./families/"禺.dhall" is now legal
Feature: Add Text/show built-in
- ... as standardized in version 6.0.0 of the language standard
- You can now convert a Text literal to its equivalent Dhall source code (which is itself a Text literal)
- This comes in handy when using Dhall code to generate JSON or Dhall code
- See: https://github.com/dhall-lang/dhall-haskell/pull/811
Feature: Add --immediate-dependencies/--transitive-dependencies flags for dhall resolve
- You can now retrieve all of your immediate or transitive dependencies as a textual list
- This simplifies integration with other command-line tools (such as file watchers)
- See: https://github.com/dhall-lang/dhall-haskell/pull/795
- See: https://github.com/dhall-lang/dhall-haskell/pull/803
Feature: dhall freeze now only freezes remote imports by default
- dhall freeze used to freeze all imports (including local imports and environment variables)
- Now dhall freeze only freezes remote imports by default, which is what most users want
- You can install freeze all imports using the --all flag
- See: https://github.com/dhall-lang/dhall-haskell/pull/808
Feature: :save and :load REPL state
- :save with no arguments now saves the REPL state to a .dhall-repl-N file
- The file format is a list of dhall repl commands
- You can use :load to load the saved state back into the REPL
- See: https://github.com/dhall-lang/dhall-haskell/pull/807
Feature: Add :hash command to dhall repl
- This lets you conveniently hash expressions within the dhall repl
- See: https://github.com/dhall-lang/dhall-haskell/pull/806
Feature: Add --check flag to dhall format
- Use this to check if the input is already formatted
- Useful for continuous integration when you want to ensure that all code under version control remains formatted
- See: https://github.com/dhall-lang/dhall-haskell/pull/810
Feature: Add UnionInputType builder for InputTypes
- This is the union analog of RecordInputType, letting you build a record explicitly instead of deriving the instance using GHC generics
- See: https://github.com/dhall-lang/dhall-haskell/pull/775
Feature: Add :set/:unset commands to dhall repl
- You can use these commands to set or unset command-line options
- Currently only setting/unsetting --explain is supported
Standards-compliance fixes:
- See: https://github.com/dhall-lang/dhall-haskell/pull/779
- See: https://github.com/dhall-lang/dhall-haskell/pull/804
- See: https://github.com/dhall-lang/dhall-haskell/pull/833
Documentation fixes:
- See: https://github.com/dhall-lang/dhall-haskell/pull/792
- See: https://github.com/dhall-lang/dhall-haskell/pull/825
Test fixes:
- See: https://github.com/dhall-lang/dhall-haskell/pull/782
- See: https://github.com/dhall-lang/dhall-haskell/pull/836
Improved error messages:
- See: https://github.com/dhall-lang/dhall-haskell/pull/812
- See: https://github.com/dhall-lang/dhall-haskell/pull/815
- See: https://github.com/dhall-lang/dhall-haskell/pull/824
Formatting fixes:
- See: https://github.com/dhall-lang/dhall-haskell/pull/831
REPL fixes:
- See: https://github.com/dhall-lang/dhall-haskell/pull/837

1.20.1

BUG FIX: Fix binary encoding to use correct standard version
- This fixes computed hashes to correctly match standard version 5.0.0
- This is not marked as a breaking change since it is a bug fix. The 1.20.0 release will be blacklisted on Hackage and users should upgrade from 1.19.* directly to 1.20.1
- See: https://github.com/dhall-lang/dhall-haskell/pull/771

1.20.0

Supports version 5.0.0 of the language standard
- See: https://github.com/dhall-lang/dhall-lang/releases/tag/v5.0.0
BREAKING CHANGE TO THE LANGUAGE: Implement standardized support for multi-line literals
- This updates the multi-line support to match the standard
- This is a breaking change because empty lines within the multi-line literal now require leading whitespace whereas previously they did not
- This is also a breaking change because now a newline is required after the opening '' quotes whereas previously it was not required
- If you use dhall format then your multi-line literals already have the necessary leading whitespace
BREAKING CHANGE TO THE LANGUAGE: constructors x = x
- Now the constructors keyword behaves like an identity function, since constructors can already be accessed as fields off the original union type.
- This is a breaking change since any record of terms that contains a constructors field will now be a forbidden mixed record of types and terms.
- This is also a breaking change if you annotated the type of what used to be a constructors record.
- dhall lint will now remove the obsolete constructors keyword for you
- See: https://github.com/dhall-lang/dhall-haskell/pull/693
- See: https://github.com/dhall-lang/dhall-haskell/pull/701
BREAKING CHANGE TO THE API: Restore Parent constructor for Local type
- This more closely matches the standard and also enables dhall format to produce a leading ../ for imports instead of ./../
- See: https://github.com/dhall-lang/dhall-haskell/pull/718
BUG FIX: Fix type-checking bug for unions
- The first fix was that the inferred type was wrong for unions where alternatives were types or kinds
- The second fix was that unions that mixed terms/types/kinds were not properly rejected
- See: https://github.com/dhall-lang/dhall-haskell/pull/763
BUG FIX: Change how dhall repl handles prior definitions
- This changes the REPL to handle previous bindings as if they were defined using a large let expression instead of adding them to the context
- This fixes some type-checking false negatives
- See: https://github.com/dhall-lang/dhall-haskell/pull/729
Feature: Autocomplete for dhall repl
- You can now auto-complete record fields, union constructors, and identifiers that are in scope
- See: https://github.com/dhall-lang/dhall-haskell/pull/727
Feature: GHCJS support
- dhall can now be built using GHCJS, although some features are still not supported for GHCJS, such as:
  - Semantic integrity checks
  - Custom HTTP headers
- Also, HTTP imports only work for URLs that support CORS
- See: https://github.com/dhall-lang/dhall-haskell/pull/739
Feature: Add support for records of records of types
- You can now nest records of types
- See: https://github.com/dhall-lang/dhall-haskell/pull/700
Feature: Add :quit command for dhall repl
- See: https://github.com/dhall-lang/dhall-haskell/pull/719
Feature: Add --json flag for dhall {encode,decode}
- You can now produce/consume CBOR expressions via JSON instead of binary
- See: https://github.com/dhall-lang/dhall-haskell/pull/717
Feature: Add decoding logic for as Text
- You can now preserve the as Text qualifier on imports when serializing them
- See: https://github.com/dhall-lang/dhall-haskell/pull/712
Prenormalize substituted expressions
- This is a performance improvement that reduces the time and memory consumption when normalizing expressions
- See: https://github.com/dhall-lang/dhall-haskell/pull/765

1.19.1

BUG FIX: Fix serious dhall lint bug
- dhall lint would sometimes remove let expressions that were still in use
- See: https://github.com/dhall-lang/dhall-haskell/pull/703
BUG FIX: Fix import caching efficiency bug
- Some imports were being wastefully fetched multiple times
- See: https://github.com/dhall-lang/dhall-haskell/pull/702
Feature: Generate dot graph to visualize import graph
- Use the dhall resolve --dot command
- See: https://github.com/dhall-lang/dhall-haskell/pull/698
- See: https://github.com/dhall-lang/dhall-haskell/pull/713
Improve HTTP error messages
- See: https://github.com/dhall-lang/dhall-haskell/pull/710

1.19.0

Supports version 4.0.0 of the language standard
- See: https://github.com/dhall-lang/dhall-lang/releases/tag/v4.0.0
BREAKING CHANGE TO THE LANGUAGE AND API: Prevent Hurkens' paradox
- This fixes a type-checking soundness bug which permitted infinite loops
- This is a breaking change because infinite loops are no longer possible
- This is also a breaking change because a record of types is now treated as a kind instead of a type
- See: https://github.com/dhall-lang/dhall-haskell/pull/680
BREAKING CHANGE TO THE LANGUAGE AND API: Doubles are now double-precision floating point numbers
- This restricts the range of Doubles to IEEE 754 double-precision floating point
- This also implies that you can no longer convert Scientific values to Dhall expressions (i.e. no Inject instance for Scientific)
- See: https://github.com/dhall-lang/dhall-haskell/pull/667
BREAKING CHANGE TO THE API: Preserve field order for record projection
- The API uses a new Dhall.Set.Set type instead of Data.Set.Set
- See: https://github.com/dhall-lang/dhall-haskell/pull/670
BREAKING CHANGE TO THE API: Add support for multi-let expressions
- This changes the Let constructor to now support storing multiple bindings per let expression
- See: https://github.com/dhall-lang/dhall-haskell/pull/675
Access constructors as if they were fields of the union type
- In other words: < Left : Bool | Right : Natural >.Left
- See: https://github.com/dhall-lang/dhall-haskell/pull/657
Support GHC 8.6
- See: https://github.com/dhall-lang/dhall-haskell/pull/669
Add support for quoted path components
- i.e. /"foo"/bar/"baz qux" or https://example.com/foo/"bar?baz"?qux
- See: https://github.com/dhall-lang/dhall-haskell/pull/690
Fix parsing of //\\ operator
- See: https://github.com/dhall-lang/dhall-haskell/commit/9d0fd42d95ab69fa64da4afd8b60d69aca8e65a6
Preserve Unicode characters when formatting code
- See: https://github.com/dhall-lang/dhall-haskell/pull/679
Allow identifier names to begin with Some
- See: https://github.com/dhall-lang/dhall-haskell/pull/658
Add subExpressions Traversal
- See: https://github.com/dhall-lang/dhall-haskell/pull/660
Add normalizeWithM for monadic normalization
- See: https://github.com/dhall-lang/dhall-haskell/pull/371
Custom normalizers now take precedence over default normalization logic
- This allows one to override the implementation of built-in operators
- See: https://github.com/dhall-lang/dhall-haskell/pull/684

1.18.0

Supports version 3.0.0 of the language standard:
- See: https://github.com/dhall-lang/dhall-lang/releases/tag/v3.0.0
BREAKING CHANGE TO THE LANGUAGE AND API: New Some/None constructors for Optional values
- Example: [ Some 1, None Natural ]
- This is a breaking change to the language because Some and None are now reserved keywords
- This is a breaking change to the API because Some and None are new constructors for the Expr type
BREAKING CHANGE TO THE LANGUAGE AND API: Support for kind polymorphism
- This adds a new Sort constant above Kind in the hierarchy
- i.e. Type : Kind : Sort
- This is a breaking change to the language because Sort is now a reserved keyword
- This is a breaking change to the API because Sort is a new constructor for the Expr type
BREAKING CHANGE TO THE API: New Dhall.Map module
- This replaces InsOrdHashMap in the API
- The primary motivation is to improve performance and to remove the dependency on insert-ordered-containers
BREAKING CHANGE TO THE API: Use standard version instead of protocol version
- The binary protocol is now versioned alongside the standard
- The ProtocolVersion type is renamed to StandardVersion and the
- --protocol-version option is renamed to --standard-version
- See: https://github.com/dhall-lang/dhall-haskell/pull/634
BUG FIX: Fix import chaining for custom header imports
- See: https://github.com/dhall-lang/dhall-haskell/pull/618
BUG FIX: Fix import chaining for imports protected by semantic integrity checks
- See: https://github.com/dhall-lang/dhall-haskell/pull/584
BUG FIX: Record literals and types produced by ∧/⫽/⩓ are now sorted
- This ensures that β-normalization is idempotent
- See: https://github.com/dhall-lang/dhall-haskell/pull/572
BUG FIX: dhall freeze now correctly handles the starting file being located outside the current working directory
- See: https://github.com/dhall-lang/dhall-haskell/commit/a22aa79d1957be9ecf166ea066e2a9a5b309e1ae
BUG FIX: Fix parsing of IPv4-mapped IPv6 addresses
- See: https://github.com/dhall-lang/dhall-haskell/pull/632
FEATURE: New --ascii flag for ASCII output
- See: https://github.com/dhall-lang/dhall-haskell/pull/570
FEATURE: New dhall encode and dhall decode subcommands
- These allow you to transform Dhall source code to and from its binary representation
- See: https://github.com/dhall-lang/dhall-haskell/pull/588
LARGE parsing performance improvements
- Parsing is about 10x-100x faster on most code
- See: https://github.com/dhall-lang/dhall-haskell/pull/591
- See: https://github.com/dhall-lang/dhall-haskell/pull/592
- See: https://github.com/dhall-lang/dhall-haskell/pull/597
- See: https://github.com/dhall-lang/dhall-haskell/pull/601
- See: https://github.com/dhall-lang/dhall-haskell/pull/602
- See: https://github.com/dhall-lang/dhall-haskell/pull/604
- See: https://github.com/dhall-lang/dhall-haskell/pull/606
Type-checking performance improvements:
- See: https://github.com/dhall-lang/dhall-haskell/pull/566
Normalization performance improvements:
- See: https://github.com/dhall-lang/dhall-haskell/pull/610
dhall freeze now caches the imports as it freezes them
- See: https://github.com/dhall-lang/dhall-haskell/pull/587
dhall freeze now refreezes imports with invalid semantic integrity checks
- See: https://github.com/dhall-lang/dhall-haskell/pull/637
dhall freeze now adds a trailing newline
- See: https://github.com/dhall-lang/dhall-haskell/pull/629
Build against megaparsec-7.0.*
- See: https://github.com/dhall-lang/dhall-haskell/pull/565
Support GHC 8.6
- See: https://github.com/dhall-lang/dhall-haskell/pull/599
- See: https://github.com/dhall-lang/dhall-haskell/pull/623
Support GHC all the way back to 7.10.3
- See: https://github.com/dhall-lang/dhall-haskell/pull/595
- See: https://github.com/dhall-lang/dhall-haskell/pull/621
Improvements to error messages:
- See: https://github.com/dhall-lang/dhall-haskell/pull/563
- See: https://github.com/dhall-lang/dhall-haskell/pull/576
- See: https://github.com/dhall-lang/dhall-haskell/pull/583
- See: https://github.com/dhall-lang/dhall-haskell/pull/589

1.17.0

This release corresponds to version 2.0.0 of the language standard
BREAKING CHANGE TO THE LANGUAGE AND API: Binary serialization support
- This is a breaking change to the hash for all semantic integrity checks
- The hash used by the semantic integrity check is now based on the binary representation instead of a text representation of the expression
- You can pin the new hashes by supplying the --protocol-version 1.0 option on the command line until you need support for newer language features
- This also includes a breaking change to ImportType in the API
BREAKING CHANGE TO THE LANGUAGE: Disallow combining records of terms and types
- This is mainly for consistency and to improve type errors that would have otherwise happened further downstream
- This should not affect the vast majority of code
- See: https://github.com/dhall-lang/dhall-haskell/pull/538
BUG FIX: Semantic integrity checks now work for imported expression using the constructors keyword
- See: https://github.com/dhall-lang/dhall-haskell/pull/554
BUG FIX: Fix α-normalization of expressions with bound variables named _
- See: https://github.com/dhall-lang/dhall-haskell/pull/524
BUG FIX: Fix isNormalized to match normalize
- See: https://github.com/dhall-lang/dhall-haskell/pull/522
BUG FIX: dhall lint now correctly handles nested let expressions
- See: https://github.com/dhall-lang/dhall-haskell/pull/555
FEATURE: Imports protected by a semantic integrity check are now cached
- See: https://github.com/dhall-lang/dhall-haskell/pull/533
The default dhall command no longer outputs the type to stderr
- You can add back the type as a type annotation using the --annotate switch
- See: https://github.com/dhall-lang/dhall-haskell/pull/544
New utilities for building InputTypes
- See: https://github.com/dhall-lang/dhall-haskell/pull/530
Improve parsing performance for long variable names
- See: https://github.com/dhall-lang/dhall-haskell/pull/526
More succinct type diffs for function types
- See: https://github.com/dhall-lang/dhall-haskell/pull/540
Identifier names can now begin with keywords
- i.e. ifChanged and lettuce are now legal identifiers
- See: https://github.com/dhall-lang/dhall-haskell/pull/551

1.16.1

Fix test failure due to missing test data file

1.16.0

BREAKING CHANGE: Consolidate input family of functions
- These now take a record of options
- This also _stack field of the Status type from [Import] to NonEmpty Import
Permit $ in quoted variable names
- See: https://github.com/dhall-lang/dhall-haskell/pull/510

1.15.1

Fix infinite loop when formatting expressions containing ?
- See: https://github.com/dhall-lang/dhall-haskell/pull/491

1.15.0

BREAKING CHANGE TO THE API: Support alternative imports using new ? operator
- This adds a new constructor which affects exhaustive pattern matches
- See: https://github.com/dhall-lang/dhall-haskell/pull/473
BREAKING CHANGE TO THE API: Add Integer/toDouble built-in function
- This adds a new constructor which affects exhaustive pattern matches
- See: https://github.com/dhall-lang/dhall-haskell/pull/434
BREAKING CHANGE TO THE API: Use strict Text instead of lazy Text
- See: https://github.com/dhall-lang/dhall-haskell/pull/455
BREAKING CHANGE TO THE API: Remove Buildable in favor of Pretty
- See: https://github.com/dhall-lang/dhall-haskell/pull/459
BREAKING CHANGE TO THE API: Removed the Parent constructor from FilePrefix
- Instead, use Here with a ".." prefix.
- See: https://github.com/dhall-lang/dhall-haskell/pull/407
BUG FIX: Disallow duplicate fields in records
- See: https://github.com/dhall-lang/dhall-haskell/pull/430
BUG FIX: Fix stripping of leading whitespace in multi-line strings
- See: https://github.com/dhall-lang/dhall-haskell/pull/469
BUG FIX: Fix formatting field access of an import
- See: https://github.com/dhall-lang/dhall-haskell/pull/471
Add dhall freeze command
- See: https://github.com/dhall-lang/dhall-haskell/pull/486
Add dhall diff command
- See: https://github.com/dhall-lang/dhall-haskell/pull/442
Add dhall lint command
- See: https://github.com/dhall-lang/dhall-haskell/pull/484
Change dhall-repl/dhall-hash/dhall-format to dhall subcommands
- i.e. dhall repl/dhall hash/dhall format
- See: https://github.com/dhall-lang/dhall-haskell/pull/435
- See: https://github.com/dhall-lang/dhall-haskell/pull/452
Add with-http cabal flag to disable support for remote imports
- See: https://github.com/dhall-lang/dhall-haskell/pull/482
Added inputFrom and inputFromWith
- These allow naming the file that the expression is coming from for better error messages
- See: https://github.com/dhall-lang/dhall-haskell/pull/464
Performance improvements
- See: https://github.com/dhall-lang/dhall-haskell/pull/420
Tutorial recommends GitHub for Prelude instead of IPFS
- See: https://github.com/dhall-lang/dhall-haskell/pull/479
Pretty-print expressions in type errors
- See: https://github.com/dhall-lang/dhall-haskell/pull/429
Formatting improvements
- See: https://github.com/dhall-lang/dhall-haskell/pull/398
- See: https://github.com/dhall-lang/dhall-haskell/pull/458
Diff improvements

1.14.0

BREAKING CHANGE TO THE LANGUAGE: Switch grammar of Natural and Integer
- Natural number literals are now unsigned and Integer literals always require a sign
- This is a VERY disruptive change to most Dhall code in the wild but was unanimously agreed upon here: https://github.com/dhall-lang/dhall-lang/issues/138
- See also: https://github.com/dhall-lang/dhall-haskell/pull/381
BREAKING CHANGE TO THE LANGUAGE: Drop support for importing directories
- Importing dir/ used to resolve to dir/@, which is no longer supported
- See: https://github.com/dhall-lang/dhall-haskell/pull/384
BREAKING CHANGE TO THE LANGUAGE: Change to the grammar for imports
- File path components can no longer contain # or ? characters
- URL imports must now contain at least one path component
- URL path components must match the grammar for file path components
- See: https://github.com/dhall-lang/dhall-haskell/pull/390
BREAKING CHANGE TO THE API: Rename Path{,Mode,Hashed,Type} to Import{,Mode,Hashed,Type}
- In practice this change is not breaking for the most common use cases since this also provides a Path type synonym for backwards compatibility
- See: https://github.com/dhall-lang/dhall-haskell/pull/376
BUG FIX: Fix α-equivalence bug when type-checking merge
- merge expressions would sometimes reject valid code due to a type-checking bug
- See: https://github.com/dhall-lang/dhall-haskell/pull/394
Improve import caching
- See: https://github.com/dhall-lang/dhall-haskell/pull/388
- See: https://github.com/dhall-lang/dhall-haskell/pull/392
Increase upper bound on tasty
- See: https://github.com/dhall-lang/dhall-haskell/pull/382
Fix lower bound on insert-ordered-containers
- See: https://github.com/dhall-lang/dhall-haskell/pull/377

1.13.1

Increase upper bound on ansi-terminal and megaparsec

1.13.0

BUG FIX: Fix semantic integrity hashing support
- Both parsing and pretty-printing semantic hashes were broken since version 1.11.0
- See: https://github.com/dhall-lang/dhall-haskell/pull/345
BUG FIX: Allow leading whitespace in interpolated expresssions
- See: https://github.com/dhall-lang/dhall-haskell/pull/369
BUG FIX: Fix deriving (Interpret) for sum types
- The types of alternatives were not correctly included in the corresponding Dhall type
- See: https://github.com/dhall-lang/dhall-haskell/pull/348
BREAKING CHANGE TO LANGUAGE: Records cannot store both types and terms
- Records can also not store type-level functions (like List)
  - Records might be allowed to store type-level functions again in the future
- This fixes a potential soundness bug
- The primarily practical consequence of this change is that if you are hosting a "package" then you will need to split terms and types from your package into different records for your users to import
- This also implies removing the ./Monoid type-level function from the ./Prelude/package.dhall record
- See: https://github.com/dhall-lang/dhall-haskell/pull/335
BREAKING CHANGE TO THE API: Replace trifecta with megaparsec
- This change the API to use the Parser type from megaparsec
- This also slightly changes the type of exprFromText
- If you program using the type classes provided by the parsers library then this is not a breaking change as that interface is preserved
- See: https://github.com/dhall-lang/dhall-haskell/pull/268
BREAKING CHANGE TO THE API: New ⩓ operator for merging record types
- Example: { foo : Text } ⩓ { bar : Bool } = { foo : Text, bar : Bool }
- This is breaking because it adds a new constructor to the Expr type
- See: https://github.com/dhall-lang/dhall-haskell/pull/342
BREAKING CHANGE TO THE API: New support for projecting a subset of fields
- Example: { x = 1, y = 2, z = 3 }.{ x, y } = { x = 1, y = 2 }
- This is breaking because it adds a new constructor to the Expr type
- See: https://github.com/dhall-lang/dhall-haskell/pull/350
API+UX feature: New support for pretty-printing diffs of Dhall expressions
- Error messages also use this feature to simplify large type mismatches
- There is also a new Dhall.Diff module
- See: https://github.com/dhall-lang/dhall-haskell/pull/336
Add version, resolve, type, and normalize sub-commands to interpreter
- See: https://github.com/dhall-lang/dhall-haskell/pull/352
Support GHC 7.10.3
- See: https://github.com/dhall-lang/dhall-haskell/pull/340
:type command in dhall-repl now only displays the type
- Before it would also display the original expression
- See: https://github.com/dhall-lang/dhall-haskell/pull/344
Trim dependency tree

1.12.0

Additional changes to support GHC 8.4
- See: https://github.com/dhall-lang/dhall-haskell/pull/331
BREAKING CHANGE TO API: Replace dependency on text-format with formatting
- This replace the Data.Text.Buildable.Buildable instances with Formatting.Buildable.Buildable instances, which is why this is a breaking change
- text-format is no longer maintained and blocking GHC 8.4 support
- See: https://github.com/dhall-lang/dhall-haskell/pull/330

1.11.1

Support GHC 8.4
- See: https://github.com/dhall-lang/dhall-haskell/pull/321
Fix α-normalization bug
- Note that this is not a type-checking bug. This only affects users who were directly using the alphaNormalize function from the Haskell API because let expressions were not correctly α-normalized
- See: https://github.com/dhall-lang/dhall-haskell/pull/319
Slight tweak to syntax highlighting
- See: https://github.com/dhall-lang/dhall-haskell/pull/324
Increase upper bound on ansi-terminal and exceptions
- See: https://github.com/dhall-lang/dhall-haskell/pull/322
- See: https://github.com/dhall-lang/dhall-haskell/pull/325

1.11.0

BREAKING CHANGE TO THE API: Fix {Natural,Optional,List}/build semantics to match standard
- This is a breaking change because the OptionalLit and ListLit constructors changed their representations to efficiently support the standard semantics
- ListLit now stores a Data.Sequence.Seq instead of a Data.Vector.Vector
- OptionalLit now stores a Maybe instead of a Data.Vector.Vector
- See: https://github.com/dhall-lang/dhall-haskell/pull/300
BREAKING CHANGE TO THE COMMAND LINE: dhall executable always formats output
- Previously you had to opt into formatting using --pretty
- Now formatting is obligatory and the --pretty flag is gone
- See: https://github.com/dhall-lang/dhall-haskell/pull/303
Feature: New :save command for dhall-repl
- Now you can save an expression to a file: ./yourFile = someExpression
- See: https://github.com/dhall-lang/dhall-haskell/pull/309
Improvement: Add new simplifications to match standard
- See: https://github.com/dhall-lang/dhall-haskell/pull/312
- See: https://github.com/dhall-lang/dhall-haskell/pull/316
Improvement: Fix equivalence check to match standard
- Practically this means that more corner cases of the language correctly type-check than before
Improvement: New --plain flag to disable syntax highlighting
- See: https://github.com/dhall-lang/dhall-haskell/pull/310
Improvement: Prelude now provides an umbrella package.dhall import
- This is primarily for convenience
- See: https://github.com/dhall-lang/dhall-haskell/pull/298
Improvement: Context is now normalized
- See: https://github.com/dhall-lang/dhall-haskell/pull/302
Replace cryptohash dependency with cryptonite
- See: https://github.com/dhall-lang/dhall-haskell/commit/5d2012927a062ec8bdf2bbaba77150344f38db77
Increase upper bound on exceptions
- See: https://github.com/dhall-lang/dhall-haskell/pull/306
Fix type error in tutorial
- See: https://github.com/dhall-lang/dhall-haskell/commit/5a9126b2f684d3236fc1e8e20e206cfaf47d97db

1.10.0

Feature: Records/unions can now have fields/alternatives that are types
- i.e. { foo = Text, bar = List } is legal now
- See: https://github.com/dhall-lang/dhall-haskell/pull/273
Feature: New dhall-repl for interactively evaluating Dhall expressions
- See: https://github.com/dhall-lang/dhall-haskell/pull/266
Feature: Syntax highlighting
- See: https://github.com/dhall-lang/dhall-haskell/pull/260
Feature: BREAKING CHANGE TO THE API: dhall-format preserves field order
- This changes the syntax tree to use an InsOrdHashMap instead of a Map
BREAKING CHANGE TO THE API: Use Haskell's Scientific type
- This is fixes the interpreter to correct handle really large/small numbers
- This also allows marshaling into Haskell's Scientific type
- See: https://github.com/dhall-lang/dhall-haskell/pull/256
BREAKING CHANGE TO THE API: Remove system-filepath/system-fileio dependencies
- Now the library uses Prelude.FilePath
- See: https://github.com/dhall-lang/dhall-haskell/pull/248
Feature: Labels can now begin with reserved names
- i.e. List/map is now a legal label
- See: https://github.com/dhall-lang/dhall-haskell/pull/255
Fix: Rendered labels are now correctly escaped if they are numbers
- See: https://github.com/dhall-lang/dhall-haskell/pull/252
Add the instance Interpret String.
- See: https://github.com/dhall-lang/dhall-haskell/pull/247
Fix: Custom contexts passed to typeWith are now checked
- This prevents a custom context from triggering an infinite loop
- See: https://github.com/dhall-lang/dhall-haskell/pull/259

1.9.1

dhall-format now emits single-quoted strings for multi-line strings
- See: https://github.com/dhall-lang/dhall-haskell/pull/237
Improved error messages for list elements with the wrong type
- See: https://github.com/dhall-lang/dhall-haskell/pull/236
Change lens dependency to lens-family-core
- See: https://github.com/dhall-lang/dhall-haskell/pull/238

1.9.0

Feature: BREAKING CHANGE TO LANGUAGE AND API: Add constructors keyword
- This new keyword generates constructors from a union type
  - See the updated Haskell tutorial for more details
- This means that constructors is now a reserved keyword
- This adds a new Constructors constructor to the Expr type
- See: https://github.com/dhall-lang/dhall-haskell/pull/199
Feature: BREAKING CHANGE TO THE API: dhall-format preserves interpolation
- This changes the TextLit constructor to represent an interpolated Text literal
- See: https://github.com/dhall-lang/dhall-haskell/pull/220
Feature: You can now define type synonyms using let
- See: https://github.com/dhall-lang/dhall-haskell/pull/202
Feature: Extend valid set of quoted labels
- See: https://github.com/dhall-lang/dhall-lang/pull/65
- See: https://github.com/dhall-lang/dhall-lang/pull/77
Performance: Improve startup time when importing files, but not URLs
- See: https://github.com/dhall-lang/dhall-haskell/pull/194
Security: localhost/127.0.0.1 imports no longer count as local imports
- Specifically: they cannot import environment variables or files
- See: https://github.com/dhall-lang/dhall-haskell/pull/197
Security: Fix potential type-checking bug
- See: https://github.com/dhall-lang/dhall-haskell/pull/198
Fix: BREAKING CHANGE TO API: Improve localization of error messages
- This required fixing the type of normalize/shift/subst to preserve the first type parameter of Expr (i.e. they no longer delete Note constructors)
- A new denote function was added for the explicit purpose of deleting Note constructors
- See: https://github.com/dhall-lang/dhall-haskell/pull/218
Expose MissingEnvironmentVariable exception type
- See: https://github.com/dhall-lang/dhall-haskell/pull/196
Add genericAuto
- See: https://github.com/dhall-lang/dhall-haskell/pull/195
Add inputWith
- See: https://github.com/dhall-lang/dhall-haskell/pull/222
AddloadWithContext
- See: https://github.com/dhall-lang/dhall-haskell/pull/215
Add pair/unit/string/list
- See: https://github.com/dhall-lang/dhall-haskell/pull/227

1.8.2

Add typeWithA for type-checking custom Embedded values
Fix dhall{,-*} executables to ignore ambient locale and use UTF8
Increase upper bound on tasty dependency

1.8.1

dhall executable can now format output using --pretty
Improved Unicode suppport on Windows

1.8.0

BREAKING CHANGE TO LANGUAGE: Add support for import integrity checks
- In practice, the likelihood of this breaking code in the wild is astronomically low
- This would only break code of the form sha256:aaa...aaa (i.e. a variabled named sha256 with a type annotation for a type with a name 64 characters long drawn from the first 6 characters of the alphabet)
BUG FIX: Fix parsing of single quotes in single-quoted strings
BUG FIX: Fix superfluous parentheses introduced by dhall-format
New dhall-hash executable
- This goes hand-in-hand with the added support for integrity checks since the executable lets you compute the current hash of an import

1.7.0

BREAKING CHANGE TO LANGUAGE: Update parser to match standardized grammar
- Trailing commas and bars no longer supported for union and record literals
- Paths no longer permit commas
- URL grammar is now RFC-compliant
- Environment variables can now be quoted to support full range of POSIX-compliant names
- Text literals support full set of JSON escape sequences (such as \u2192)
BREAKING CHANGE TO LANGUAGE: Single quoted strings strip leading newlines
BUG FIX: Fixed type-checking infinite loops due to non-type-checked variables in context
BUG FIX: Fixed type-checking bug due to missing context when type-checking certain expressions
BUG FIX: Fixed type-checking bug due to off-by-one errors in name shadowing logic
New dhall-format executable to automatically format code
Performance optimizations to Natural/fold and List/fold
Improved parsing performance (over 3x faster)
Union literals can now specify the set value anywhere in the literal
- i.e. < A : Integer | B = False | C : Text >
New Inject instance for ()
Several tutorial fixes and improvements

1.6.0

BREAKING CHANGE TO THE API: Drop support for GHC 7.*
BREAKING CHANGE TO THE API: Add support for customizing Dhall import
- This is a breaking change because this changes the type of loadWith
BREAKING CHANGE TO THE API: Add field to UnboundVariable error containing
BUG FIX: Fix parsing single quotes in string literals the name of the unbound variable
Add List/concatMap to the Prelude
You can now derive Inject and Interpret for types with unlabeled fields
Add new instances for Interpret:
- []
- (,)
Add new instance for Inject
- [], Data.Set.Set, Data.Sequence.Seq
- (,)
- Int, Word8, Word16, Word32, Word64
Add Eq instance for Src

1.5.1

Increase upper bound on vector and optparse-generic

1.5.0

BREAKING CHANGE: Add list concatenation operator: (#)
- This is a breaking change because it adds a new constructor to the Expr type which breaks exhaustive pattern matches
BREAKING CHANGE: Add Interpret support for lazy Text
- This is a breaking change because it renames text to strictText
Add Interpret instance for decoding (a limited subset of) Dhall functions
Dhall no longer requires Template Haskell to compile
- This helps with cross-compilation
Add rawInput utility for decoding a Haskell value from the Expr type
Add loadWith/normalizeWith utilities for normalizing/importing modules with a custom context
Export Type constructor

1.4.2

Fix missing Prelude files in package archive uploaded to Hackage

1.4.1

Fix missing tests/Tutorial.hs module in package archive uploaded to Hackage

1.4.0

BREAKING CHANGE TO THE LANGUAGE AND API: You can now supply custom headers for URL imports with the new using keyword
- This is a breaking change to the language because this adds a new reserved using keyword
- This is a breaking change to the API because this adds a new field to the URL constructor to store optional custom headers
BUG FIX: : is no longer a disallowed path character
- This was breaking URL imports with a port
BUG FIX: If you import a home-anchored path (i.e. ~/foo) and that imports a relative path (like ./bar), then the canonical path of the relative import should be home-anchored (i.e. ~/bar). However, there was a bug that made lose the home anchor (i.e. ./foo/bar), which this release fixes likely fail due to no longer being home-anchored (i.e. `./foob
Add support for string interpolation
merge no longer requires a type annotation if you are merging at least one alternative
Expanded Prelude
- ./Prelude/Optional/all
- ./Prelude/Optional/any
- ./Prelude/Optional/filter
- ./Prelude/Optional/length
- ./Prelude/Optional/null
- ./Prelude/Text/concatMap
- ./Prelude/Text/concatMapSep
- ./Prelude/Text/concatSep
Rearrange detailed error messages to put summary information at the bottom of the message

1.3.0

BREAKING CHANGE TO THE API: Add support for new primitives, specifically:
- (//) - Right-biased and shallow record merge
- Optional/build (now a built-in in order to support build/fold fusion)
- Natural/show
- Integer/show
- Double/show
- Natural/toInteger
- These all add new constructors to the Expr type, which would break exhaustive pattern matches
BREAKING CHANGE TO THE LANGUAGE: Imported paths and URLs no longer support the characters: "()[]{}<>:"
- This reduces the number of cases where you have to add a space after imports
- Note that this does not exclude the : in the URL scheme (i.e. http://)
Increase connection timeout for imports
Variable names now allow the - character for all but the first character
You can now escape identifiers with backticks
- This lets you name identifiers so that they don't conflict with reserved key words
- This is most useful when converting Dhall to other file formats (like JSON) where you might need to emit a field that conflicts with one of Dhall's reserved keywords
New --version flag for the dhall executable

1.2.0

BREAKING CHANGE: Add support for customizing derived Interpret instances
- This is a breaking change to the Dhall library API since this changes the signature of the Interpret class by replacing the auto method with a more general autoWith method. This autoWith now takes an InterpretOptions argument that lets you customize derived field and constuctor names
- In practice user programs that use the common path will be unaffected by this change
- This is not a breaking change to the Dhall language
BREAKING CHANGE: Type annotations now bind more tightly than lambda abstraction
- This is a breaking change to the Dhall language. An expression like this:
```
λ(x : A) → y : B
```
  ... used to parenthesized implicitly as:
```
(λ(x : A) → y) : T
```
  ... but is now parenthesized implicitly as:
```
λ(x : A) → (y : T)
```
  This is now consistent with Haskell's precedence and also consistent with the precedence of List and Optional type annotations
- This change affects programs with an expression like this:
```
-- Assuming that `y : B`
λ(x : A) → y : A → B
```
  The above program would type-check before this change but not type-check after this change. You would you need to fix the above program by either changing the type signature to annotate just the type of y like this:
```
λ(x : A) → y : B
```
  ... or by adding explicit parentheses like this:
```
(λ(x : A) → y) : A → B
```
- This is not a breaking change to the Dhall library API
BREAKING CHANGE: Add support for importing a path's contents as raw Text by adding as Text after the import
- This is a breaking change to the Dhall language
- This is technically a breaking change, but is extremely unlikely to affect you program. This only changes the behavior of old programs that had an expression of the form:
```
/some/imported/function as Text
```
  ... where /some/imported/function is an imported function being applied to two arguments, the first of which is a bound variable named as and the second of which is the type Text
- This is not a breaking change to the Dhall library API
BREAKING CHANGE: Add support for importing environment variables using env:VAR syntax
- This is a breaking change to the Dhall library API since it adds a new Path constructor
- This also technically a breaking change to the Dhall language but extremely unlikely to affect your program. This only changes the behavior of old programs that had an expression of the form:
```
env:VAR
```
  ... where env was the name of a bound variable and :VAR was a type annotation without spaces around the type annotation operator
  
  After this change the program would be interpreted as an import of the contents for the environment variable named VAR
BREAKING CHANGE: Support importing paths relative to home directory using ~/some/path syntax
- This is a breaking change to the Dhall library API since it adds a new field to the File constructor indicating whether or not the imported path is relative to the home directory
- This is not a breaking change to the Dhall language and the new syntax does not override any old syntax
Permit trailing commas and bars in record/union syntax
Improve location information for parsing errors

1.1.0

BREAKING CHANGE: Non-empty lists no longer require a type annotation
- This is a breaking change to the Haskell library, not the Dhall language
- This change does not break existing Dhall programs
- The Expr type was modified in a non-backwards-compatible way
Add new exprA parser
Add new InvalidType exception if input fails on an invalid Type
Improve documentation and tutorial

1.0.2

Add support for Nix-style "double single-quote" multi-line string literals
Add isNormalized
Improve documentation and tutorial
Build against wider range of http-client versions

1.0.1

Initial release

1.0.0

Accidental premature upload to Hackage. This release was blacklisted