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# Morel release history and change log

For a full list of releases, see
<a href="https://github.com/hydromatic/morel/releases">GitHub</a>.

<!--
## <a href="https://github.com/hydromatic/morel/releases/tag/morel-0.x.0">0.x.0</a> / xxxx-xx-xx

Release 0.x.0 ...

Contributors:

### Features

### Bug-fixes and internal improvements

### Build and tests

### Component upgrades

### Site and documentation

* [[MOREL-xxx](https://github.com/hydromatic/morel/issues/xxx)]
  Release 0.x.0
-->

## <a href="https://github.com/hydromatic/morel/releases/tag/morel-0.6.0">0.6.0</a> / 2024-05-02

Release 0.6.0 generalizes queries with
[universal and existential quantification](https://github.com/hydromatic/morel/issues/241)
(`forall` and `exists`) and adds a keyword for logical implication (`implies`).
The new `with` keyword allows
[functional update of record values](https://github.com/hydromatic/morel/issues/249).

Usability of the shell is improved by
[tabular mode](https://github.com/hydromatic/morel/issues/259),
and
[`showAll`](https://github.com/hydromatic/morel/issues/260)
and
[`clearEnv`](https://github.com/hydromatic/morel/issues/251)
functions.

In preparation for
[operator overloading](https://github.com/hydromatic/morel/issues/237)
we have
[tuned the performance of the unifier](https://github.com/hydromatic/morel/issues/246)
that powers Morel's type-inference.

Contributors:
Julian Hyde

### Features

* [[MOREL-259](https://github.com/hydromatic/morel/issues/259)]
  Tabular mode
* [[MOREL-249](https://github.com/hydromatic/morel/issues/249)]
  Add `with` operator (functional update notation for record values)
* [[MOREL-260](https://github.com/hydromatic/morel/issues/260)]
  Add function `Sys.showAll ()`
* [[MOREL-251](https://github.com/hydromatic/morel/issues/251)]
  Add function `Sys.clearEnv ()`
* [[MOREL-246](https://github.com/hydromatic/morel/issues/246)]
  Tune unifier
* [[MOREL-241](https://github.com/hydromatic/morel/issues/241)]
  Universal and existential quantification (`forall` and `exists`) and
  implication (`implies`)

### Bug-fixes and internal improvements

* [[MOREL-253](https://github.com/hydromatic/morel/issues/253)]
  Scalar `yield` after singleton record `yield` throws
  "Conversion to core did not preserve type"
* [[MOREL-258](https://github.com/hydromatic/morel/issues/258)]
  `skip` and `take` in query with unbounded variable give error
* Add method `PairList.viewOf(Map)`
* Allow `Sys` to be evaluated and printed in the shell
* Refactor `NameGenerator`
* [[MOREL-252](https://github.com/hydromatic/morel/issues/252)]
  When unparsing Morel, try to generate qualified identifiers less often
* Refactor: Define built-in datatypes in an enum
* Refactor: Omit declarations from type-unification
* In `PairList`, add a static `copyOf` method, and enable `set` and `remove`
  methods
* The `toString` methods of `RelList` and `Binding` should not print the
  contents of tables
* [[MOREL-250](https://github.com/hydromatic/morel/issues/250)]
  Inliner generates invalid plan if dead code occurs in a nested `let`
* [[MOREL-248](https://github.com/hydromatic/morel/issues/248)]
  Optimize method `Static.transformEager` for `List` and `Collection` arguments
* [[MOREL-247](https://github.com/hydromatic/morel/issues/247)]
  Cannot translate an expression that contains type annotations
* In `class Static`, add methods `last`, `skipLast`

### Build and tests

* Reduce CI timeout
* Checkstyle should require that braces around blocks in `case:` are at the
  start of the line
* [[MOREL-245](https://github.com/hydromatic/morel/issues/245)]
  Enable google-java-format

### Component upgrades

* Bump calcite from 1.38 to 1.39
* Bump checkstyle from 10.21.4 to 10.23.1
* Bump guava from 33.4.0-jre to 33.4.5-jre,
  and raise minimum from 21.0 to 23.1-jre
* Bump guava from 33.4.5-jre to 33.4.8-jre
* Bump jdk from 21 to 24;
  we still support all Java versions JDK 8 and higher
* Bump junit-jupiter from 5.12.0 to 5.12.2
* Bump maven from 3.8.4 to 3.9.9
* Bump maven-surefire-plugin from 3.5.2 to 3.5.3

### Site and documentation

* [[MOREL-261](https://github.com/hydromatic/morel/issues/261)]
  Release 0.6.0
* [Document query expressions](docs/query.md)
* In release notes, use the '0.x.0' format for releases

## <a href="https://github.com/hydromatic/morel/releases/tag/morel-0.5.0">0.5.0</a> / 2025-03-04

Release 0.5.0 extends the syntax of the `from` expression
([`distinct`](https://github.com/hydromatic/morel/issues/231),
[`into` and `through`](https://github.com/hydromatic/morel/issues/231) keywords,
[comma-separated scans](https://github.com/hydromatic/morel/issues/216),
and [unbounded variables](https://github.com/hydromatic/morel/issues/202)).
Morel now allows
[`fn` to have multiple branches, like `case`](https://github.com/hydromatic/morel/issues/230).
We have improved code generation for a singleton `case` expression,
and implemented the
[`Int` structure](https://github.com/hydromatic/morel/issues/228) as defined by the
[Standard ML Basis Library](https://smlfamily.github.io/Basis/integer.html#Int:STR:SPEC).

Contributors:
Julian Hyde

### Features

* [[MOREL-231](https://github.com/hydromatic/morel/issues/231)]
  Add `distinct` keyword as shorthand for `group` with all fields and no
  aggregate functions
* [[MOREL-230](https://github.com/hydromatic/morel/issues/230)]
  Allow lambda (`fn`) to have multiple branches, similar to `case`
* [[MOREL-228](https://github.com/hydromatic/morel/issues/228)]
  `Int` structure
* [[MOREL-171](https://github.com/hydromatic/morel/issues/171)]
  Add `into` and `through` clauses to `from` expression
* Add function `Interactive.useSilently`
* [[MOREL-216](https://github.com/hydromatic/morel/issues/216)]
  Allow comma-separated scans in `join`, and `on` in the `from` clause
* [[MOREL-202](https://github.com/hydromatic/morel/issues/202)]
  Allow unbounded variables (`from` and `join` without `in`), and remove
  `suchthat` keyword
* Inline singleton `case`
* [[MOREL-213](https://github.com/hydromatic/morel/issues/213)]
  Require that a non-terminal `yield` step is a record expression

### Bug-fixes and internal improvements

* Number type variables left-to-right
* Improve formatting of function types
* Validate field references
* Add `Core.Tuple.forEach`
* Add `Static.find` and `PairList.firstMatch`
* Add `RecordType.mutableMap`
* Make `file.smli` test less flaky

### Build and tests

* Add Australia, cakes tests from
  [MiniZinc tutorial](https://docs.minizinc.dev/en/stable/modelling.html)
* Enable tests for
  [[MOREL-43](https://github.com/hydromatic/morel/issues/43)]

### Component upgrades

* Bump calcite from 1.36 to 1.38
* Bump build-helper-maven-plugin from 3.5.0 to 3.6.0
* Bump checkstyle from 10.12.7 to 10.21.4
* Bump guava from 33.0.0-jre to 33.4.0-jre
* Bump hamcrest from 2.2 to 3.0
* Bump hsqldb from 2.7.2 to 2.7.4
* Bump junit.jupiter from 5.10.1 to 5.12.0
* Bump maven-checkstyle-plugin from 3.3.1 to 3.6.0
* Bump maven-compiler-plugin from 3.12.1 to 3.14.0
* Bump maven-enforcer-plugin from 3.4.1 to 3.5.0
* Bump maven-javadoc-plugin from 3.6.3 to 3.11.2
* Bump maven-project-info-reports-plugin from 3.5.0 to 3.9.0
* Bump maven-surefire-plugin from 3.2.3 to 3.5.2
* Bump versions-maven-plugin from 2.16.2 to 2.18.0

### Site and documentation

* Copy-edit documentation
* Add javadoc badge to README
* [[MOREL-243](https://github.com/hydromatic/morel/issues/243)]
  Release 0.5.0

## <a href="https://github.com/hydromatic/morel/releases/tag/morel-0.4.0">0.4.0</a> / 2024-01-04

Release 0.4.0 extends `from` syntax, adding
<a href="https://github.com/hydromatic/morel/issues/129">`suchthat`</a>,
<a href="https://github.com/hydromatic/morel/issues/204">`take` and `skip`</a>
clauses; allows identifiers to be
<a href="https://github.com/hydromatic/morel/issues/71">quoted using backticks</a>;
improves pretty-printing of
<a href="https://github.com/hydromatic/morel/issues/206">tuples</a> and
<a href="https://github.com/hydromatic/morel/issues/210">long lines</a>.

Contributors:
Julian Hyde,
Rette66

### Features

* [[MOREL-204](https://github.com/hydromatic/morel/issues/204)]
  Add `take` and `skip` relational operators
* [[MOREL-209](https://github.com/hydromatic/morel/issues/209)]
  File reader, and progressive types
* [[MOREL-210](https://github.com/hydromatic/morel/issues/210)]
  Fold long types when printing
* Rename `Option.flatten` to `Option.join`
* [[MOREL-71](https://github.com/hydromatic/morel/issues/71)]
  Allow identifiers to be quoted using backticks
* [[MOREL-206](https://github.com/hydromatic/morel/issues/206)]
  Indent tuples when printing
* [[MOREL-129](https://github.com/hydromatic/morel/issues/129)]
  Define relations via constrained iterations, and introduce a `suchthat`
  keyword to use them

### Bug-fixes and internal improvements

* Add `directory` property to `Session`
* Add type parameter to `Core.Literal.unwrap()` method
* [[MOREL-208](https://github.com/hydromatic/morel/issues/208)]
  `FromBuilder` should remove trivial `yield` step between two scan steps
* [[MOREL-205](https://github.com/hydromatic/morel/issues/205)]
  Pattern that uses nested type-constructors should not be considered
  redundant
* Add utility methods `Static.transform` and `transformEager`
* [[MOREL-203](https://github.com/hydromatic/morel/issues/203)]
  Cannot deduce type for `from b in [SOME true, NONE]`
* Refactor: In `Unifier.Variable`, store ordinal rather than computing it
* Refactor: Rename `Ord.forEach` to `forEachIndexed`
* In `CoreBuilder`, add `tuple(TypeSystem, Exp...)`, a more convenient
  `apply`
* Simplify `EnvShuttle`, `EnvVisitor` by adding `push` method
* Add `interface PairList` and `interface ImmutablePairList`
* Add method `Static.nextPowerOfTwo`
* [[MOREL-201](https://github.com/hydromatic/morel/issues/201)]
  `Real.signBit` gives different result on JDK 19/ARM

### Build and tests

* Run `script.sml` in tests
* [[MOREL-207](https://github.com/hydromatic/morel/issues/207)]
  Detect and fix flaky tests
* Disallow static star import
* [[MOREL-200](https://github.com/hydromatic/morel/issues/200)]
  In the test suite, run arbitrary "lint" checks on code
* [[MOREL-198](https://github.com/hydromatic/morel/issues/198)]
  Idempotent mode for test scripts
* Add a test for various closure and recursion scenarios
* Allow CI runs to be triggered manually, and monthly

### Component upgrades

* Bump build-helper-maven-plugin from 3.3.0 to 3.5.0
* Bump calcite from 1.32.0 to 1.36.0
* Bump checkstyle from 10.3.4 to 10.12.7
* Bump guava from 31.1-jre to 33.0.0-jre;
  increase minimum guava version from 19.0 to 21.0
* Bump hsqldb from 2.7.0 to 2.7.2
* Bump javacc from 7.0.12 to 7.0.13
* Bump jdk to 21; minimum jdk is still 8
* Bump jline from 3.21.0 to 3.25.0
* Bump junit-jupiter from 5.9.1 to 5.10.1
* Bump maven-checkstyle-plugin from 3.2.0 to 3.3.1
* Bump maven-compiler-plugin from 3.10.1 to 3.12.1
* Bump maven-enforcer-plugin from 3.1.0 to 3.4.1
* Bump maven-javadoc-plugin from 3.4.1 to 3.6.3
* Bump maven-project-info-reports-plugin from 3.4.1 to 3.5.0
* Bump maven-release-plugin from 2.4.2 to 3.0.1
* Bump maven-scm-provider-gitexe from 1.9.1 to 2.0.1
* Bump maven-site-plugin from 3.12.1 to 4.0.0-M13
* Bump maven-source-plugin from 3.2.1 to 3.3.0
* Bump maven-surefire-plugin from 2.22.2 to 3.2.3
* Bump slfj from 2.0.3 to 2.1.0-alpha1
* Add versions-maven-plugin version 2.16.2
* [[MOREL-199](https://github.com/hydromatic/morel/issues/199)]
  Support JDK 19 and 20

### Site and documentation

* [[MOREL-211](https://github.com/hydromatic/morel/issues/211)]
  Release 0.4.0
* Add Maven Central badge to `README.md`

## <a href="https://github.com/hydromatic/morel/releases/tag/morel-0.3.0">0.3.0</a> / 2022-10-02

Release 0.3.0 extends `from` syntax, adding an
<a href="https://github.com/hydromatic/morel/issues/20">`order` clause</a>,
allowing multiple
<a href="https://github.com/hydromatic/morel/issues/52">`yield`</a>,
<a href="https://github.com/hydromatic/morel/issues/21">`group` and `where`</a>
steps in any order,
<a href="https://github.com/hydromatic/morel/issues/11">variable `=` value</a>,
<a href="https://github.com/hydromatic/morel/issues/31">patterns in `in`</a>.
The compiler now detects
<a href="https://github.com/hydromatic/morel/issues/55">redundant and exhaustive matches</a>,
and supports
<a href="https://github.com/hydromatic/morel/issues/54">views and inlining</a>.
We add the
<a href="https://github.com/hydromatic/morel/issues/86">use</a> function
and standard structures
<a href="https://github.com/hydromatic/morel/issues/88">Math</a> and
<a href="https://github.com/hydromatic/morel/issues/102">Real</a>
to the standard library.
Integration with
<a href="https://github.com/hydromatic/morel/issues/40">Apache Calcite</a>
allows us to translate whole programs to relational algebra.

Contributors:
Gabriel Tejeda,
Gavin Ray,
Julian Hyde,
Sergey Nuyanzin

### Features

* [[MOREL-165](https://github.com/hydromatic/morel/issues/165)]
  Improve message when type resolution cannot deduce full record type
* [[MOREL-159](https://github.com/hydromatic/morel/issues/159)]
  `from` should not have a singleton record type unless it ends with a
  singleton record `yield`
* [[MOREL-147](https://github.com/hydromatic/morel/issues/147)]
  Allow Calcite schemas to contain sub-schemas
* [[MOREL-138](https://github.com/hydromatic/morel/issues/138)]
  Type annotations in patterns, function declarations and expressions
* [[MOREL-55](https://github.com/hydromatic/morel/issues/55)]
  Analyze match coverage, detecting redundant and exhaustive matches
* Satisfiability prover
* [[MOREL-118](https://github.com/hydromatic/morel/issues/118)]
  Report positions in error messages and exceptions
* [[MOREL-105](https://github.com/hydromatic/morel/issues/105)]
  Allow identifiers to contain prime characters (`'`)
* [[MOREL-70](https://github.com/hydromatic/morel/issues/70)]
  Polymorphic datatype
* [[MOREL-104](https://github.com/hydromatic/morel/issues/104)]
  Make functions top-level
* [[MOREL-103](https://github.com/hydromatic/morel/issues/103)]
  Layered patterns (`as`), and composite `val`
* [[MOREL-102](https://github.com/hydromatic/morel/issues/102)]
  `Real` structure
* Allow quick eager evaluation for functions/operators with more than one
  argument
* [[MOREL-96](https://github.com/hydromatic/morel/issues/96)]
  Print control
* [[MOREL-100](https://github.com/hydromatic/morel/issues/100)]
  Allow double-quote and backslash in string and char literals
* [[MOREL-88](https://github.com/hydromatic/morel/issues/88)]
  `Math` structure
* Floating point: `posInf`, `negInf`, `NaN`, and negative zero
* [[MOREL-94](https://github.com/hydromatic/morel/issues/94)]
  Wordle solver
* [[MOREL-95](https://github.com/hydromatic/morel/issues/95)]
  Mutually recursive functions
* Add `Relational.iterate`, which allows "recursive queries" such as
  transitive closure
* [[MOREL-69](https://github.com/hydromatic/morel/issues/69)]
  Add `compute` clause, for monoid comprehensions
* [[MOREL-86](https://github.com/hydromatic/morel/issues/86)]
  Add `use` function, to read and execute source from a file
* [[MOREL-72](https://github.com/hydromatic/morel/issues/72)]
  Join
* [[MOREL-11](https://github.com/hydromatic/morel/issues/11)]
  In `from` clause, allow 'variable = value'
* [[MOREL-62](https://github.com/hydromatic/morel/issues/62)]
  Add function `Relational.only`, which allows scalar sub-queries
* [[MOREL-65](https://github.com/hydromatic/morel/issues/65)]
  In the shell (REPL), use prompt '`-`' and continuation '`=`'
* [[MOREL-51](https://github.com/hydromatic/morel/issues/51)]
  Add `Relational.exists` function, and push it down to Calcite
* Add `morel.lang`, Morel language definition for the Linux 'highlight'
  command
* [[MOREL-60](https://github.com/hydromatic/morel/issues/60)]
  Push `elem`, `notelem` and `not ... elem` down to Calcite (as SQL `IN`
  and `NOT IN`)
* [[MOREL-52](https://github.com/hydromatic/morel/issues/52)]
  Allow multiple `yield` steps in `from`
* [[MOREL-45](https://github.com/hydromatic/morel/issues/45)]
  Translate `List.filter` as if user had written `where`;
  and `List.map` to `yield`
* [[MOREL-57](https://github.com/hydromatic/morel/issues/57)]
  `group` with empty key should emit one row
* [[MOREL-54](https://github.com/hydromatic/morel/issues/54)]
  Views (parameterized functions that return a relation) and inlining
* [[MOREL-53](https://github.com/hydromatic/morel/issues/53)]
  Optimize core language by inlining expressions
* [[MOREL-42](https://github.com/hydromatic/morel/issues/42)]
  Add a `morel` Calcite UDF, to allow hybrid plans with a mixture of relational
  and non-relational
* [[MOREL-40](https://github.com/hydromatic/morel/issues/40)]
  Translate to full Calcite algebra
* [[MOREL-46](https://github.com/hydromatic/morel/issues/46)]
  Core language
* [[MOREL-48](https://github.com/hydromatic/morel/issues/48)]
  Deduce types when a function is applied to a record selector
* [[MOREL-44](https://github.com/hydromatic/morel/issues/44)]
  Session variables
* [[MOREL-41](https://github.com/hydromatic/morel/issues/41)]
  Add `Sys.plan ()` function, to display plans from the shell
* [[MOREL-39](https://github.com/hydromatic/morel/issues/39)]
  Implement built-in `vector` and `order` data types
* [[MOREL-38](https://github.com/hydromatic/morel/issues/38)]
  Implement built-in `option` datatype and supporting functions
* [[MOREL-37](https://github.com/hydromatic/morel/issues/37)]
  Raise exceptions in built-in functions
* [[MOREL-25](https://github.com/hydromatic/morel/issues/25)]
  Add `o` (function composition) and `@` (list concatenation) operators
* [[MOREL-36](https://github.com/hydromatic/morel/issues/36)]
  In record pattern, make labels optional, and disallow `...` anywhere but end
* [[MOREL-34](https://github.com/hydromatic/morel/issues/34)]
  Functions in relations
* [[MOREL-27](https://github.com/hydromatic/morel/issues/27)]
  Create objects for built-in structures `List` and `String`, and allow
  `structure.name` references
* [[MOREL-33](https://github.com/hydromatic/morel/issues/33)]
  Add `elem`, `notelem` operators
* [[MOREL-30](https://github.com/hydromatic/morel/issues/30)]
  Add `union`, `intersect`, `except` operators
* [[MOREL-31](https://github.com/hydromatic/morel/issues/31)]
  In `from` expression, allow `in` to assign to pattern
* [[MOREL-29](https://github.com/hydromatic/morel/issues/29)]
  Overload `+` operator to allow both `int` and `real` arguments
* [[MOREL-24](https://github.com/hydromatic/morel/issues/24)]
  Use `=` rather than `as` for assigning column aliases in `group` and `compute`
* [[MOREL-23](https://github.com/hydromatic/morel/issues/23)]
  Default arguments for aggregate functions
* [[MOREL-17](https://github.com/hydromatic/morel/issues/17)]
  Allow `from` clause that defines 0 sources
* [[MOREL-20](https://github.com/hydromatic/morel/issues/20)]
  Add `order` clause
* In `compute` clause of `group`, apply `of` expression to each row
* [[MOREL-21](https://github.com/hydromatic/morel/issues/21)]
  In `from`, allow multiple `group` and `where` clauses in any order, optionally
  followed by `yield`

### Bug-fixes and internal improvements

* [[MOREL-179](https://github.com/hydromatic/morel/issues/179)]
  In compilation environment, use name + ordinal as the key, not just name, to
  accommodate variable copies caused by inlining
* Refactor: Move list methods into `Static`
* In `CoreBuilder`, add methods for frequently used operations: `equals`,
  `lessThan`, `only` etc.
* Allocate `bool` literals (`true` and `false`) once in `CoreBuilder`
* Keywords should be lower case
* [[MOREL-101](https://github.com/hydromatic/morel/issues/101)]
  Join variables are out of order in the rows sent to an aggregate function
* [[MOREL-99](https://github.com/hydromatic/morel/issues/99)]
  Script parser hangs if it encounters invalid syntax, and ignores comments at
  ends of files
* Refactor: `Array` to `List`, `List` to `Consumer`
* Refactor: move `Shell` state into new `interface Config`
* Tuning
* Rename `Option.join` to `flatten` (to make way for the `join` keyword)
* [[MOREL-73](https://github.com/hydromatic/morel/issues/73)]
  Keywords must be lower case
* [[MOREL-64](https://github.com/hydromatic/morel/issues/64)]
  `order` after `yield` gives 'unbound variable' error
* [[MOREL-67](https://github.com/hydromatic/morel/issues/67)]
  In `compute` clause, the key value should be available but is null
* During inlining, use '_' as delimiter for qualified variable names
* [[MOREL-59](https://github.com/hydromatic/morel/issues/59)]
  Converting an empty list to relational algebra throws
* Add `Core.Yield` step, and obsolete `Core.yieldExp`
* Rationalize order of Java 'import' statements
* Always inline atomic variables
* Add method `Static.shorterThan(Iterable, int)`
* [[MOREL-49](https://github.com/hydromatic/morel/issues/49)]
  Function argument `()` should have type `unit`, not 0-tuple
* [[MOREL-50](https://github.com/hydromatic/morel/issues/50)]
  Type resolver does not resolve all fields of record types
* Improve field names, e.g. rename `Exp e` to `Exp exp`
* Remove overrides of `toString()` method in `Environment` and `EvalEnv`
* Factor `Converter` out of `CalciteForeignValue`
* Refactor: rename `let` fields
* Add `enum Prop`, for strongly-typed properties
* [[MOREL-13](https://github.com/hydromatic/morel/issues/13)]
  Garbage-collect obscured variables
* AST that contains a call to `op +` is unparsed incorrectly
* Refactor `DataSet`
* `TypeVisitor` should visit parameter types inside `DataType`
* [[MOREL-35](https://github.com/hydromatic/morel/issues/35)]
  Record pattern in `from` mixes up fields if not in alphabetical order
* Deduce type of polymorphic field in tuple or record
* Add tracing to `Unifier`
* Move `class TypeResolver.TypeMap` to top-level
* Correct order of numeric labels in records, and allow 0 as a label
* A record with a field named "1" is a record, not a tuple
* During validation, replace `From.sources` if rewrites occur
* [[MOREL-28](https://github.com/hydromatic/morel/issues/28)]
  The `sum` aggregate function only works on `int` values
* [[MOREL-26](https://github.com/hydromatic/morel/issues/26)]
  Cannot parse `()` as pattern
* Morel shell should work even if Apache Maven is not installed
* [[MOREL-19](https://github.com/hydromatic/morel/issues/19)]
  `AssertionError: unknown FUN_DECL`
* [[MOREL-22](https://github.com/hydromatic/morel/issues/22)]
  Character literal should unparse as `#"a"`, not `"a"`

### Build and tests

* Bump `slf4j-api` from 2.0.2 to 2.0.3
* Bump `hsqldb` from 2.5.1 to 2.7.0
* Add `hsqldb-version` parameter to CI
* Add `interface Tracer`, so that tests can check for several events during the
  lifecycle
* Bump `git-commit-id-plugin` from 2.1.9 to 4.9.10
* Bump `checkstyle` from 7.8.2 to 10.3.4,
  `maven-checkstyle-plugin` from 3.0.0 to 3.1.2,
  `maven-source-plugin` from 2.2.1 to 3.2.1,
  `maven-compiler-plugin` from 2.3.2 to 3.10.1,
  `build-helper-maven-plugin` from 1.9 to 3.3.0
* Bump `calcite-core` from 1.29.0 to 1.32.0
* Make `ShellTest` more robust
* Turn off Travis CI
* Bump `hsqldb` from 2.3.1 to 2.5.1,
  `foodmart-data-hsqldb` from 0.4 to 0.5,
  `scott-data-hsqldb` from 0.1 to 0.2
* Bump `maven-project-info-reports-plugin` from 2.9 to 3.4.1
* Bump `maven-enforcer-plugin` from 3.0.0-M1 to 3.1.0
* Bump `maven-javadoc-plugin` from 3.0.1 to 3.4.1
* Bump `javacc-maven-plugin` from 3.0.0 to 3.0.3
* Test Guava versions 19.0 to 31.1-jre in CI
* Bump `guava` from 21.0 to 23.0
* Bump `jline` from 3.16.0 to 3.21.0
* Bump `maven-surefire-plugin` from 3.0.0-M3 to 3.0.0-M7
* Bump `jsr305` from 1.3.9 to 3.0.2
* Bump `slf4j-api` from 1.7.25 to 2.0.2
* Bump `junit-jupiter.version` from 5.7.2 to 5.9.1
* Bump `javacc` from 7.0.5 to 7.0.12
* Enable Dependabot
* Run CI on multiple Java versions, with Javadoc
* [[MOREL-107](https://github.com/hydromatic/morel/issues/107)]
  `ShellTest` is non-deterministic
* Add GitHub workflow to build and test
* Move project to 'hydromatic' GitHub organization
* Bump `maven` from 3.6.3 to 3.8.4
* Upgrade `calcite-core` to 1.29
* In parser tests, make sure there are no characters after the expression being
  parsed
* Refactor: Test fixture for `ShellTest`
* Refactor: Move `ScriptTest.Utils` to top-level `class TestUtils`
* Bump `jline` from 3.12.1 to 3.16.0, to give support for `xrvt` terminals
* Add tests for 'StrangeLoop 2021' talk
* Travis: quote variables, skip install
* Split `hybrid.sml` out of `foreign.sml`
* Docker login
* `LearningMatcher` makes it easier to ensure that two queries have the same
  plan or same results
* In tests, move implementations of `interface Matcher` into new utility
  `class Matchers`
* Bump `calcite-core` to 1.27
* Run tests in parallel
* [[MOREL-47](https://github.com/hydromatic/morel/issues/47)]
  Bump `junit` from 4.11 to 5.7.2,
  `hamcrest` from 1.3 to 2.2
* Add tests for blog post 'Aggregate queries in Morel'
* Add tests for blog post 'Word Count revisited'
* Bump `javacc` from 4.0 to 7.0.5,
  `maven-javacc-plugin` from 2.4 to 3.0.0

### Site and documentation

* [[MOREL-181](https://github.com/hydromatic/morel/issues/181)]
  Release 0.3.0
* Update operator list in `README`
* In reference, re-order the `String` and `Vector` built-in functions
* Add example of matching regular expressions using combinators
* Add missed brackets and semicolons in `README`
* Improve Morel picture on home page
* Add functions and types to Morel language reference
* Add build status to home page
* Another example of a recursive query: Floyd-Warshall algorithm for shortest
  path in a weighted graph
* Add examples of recursive queries and fixed-point algorithms
* Add Morel logo and square image

## <a href="https://github.com/hydromatic/morel/releases/tag/morel-0.2.0">0.2.0</a> / 2020-03-10

The first release since smlj was renamed to Morel includes major
improvements to the type system and relational extensions. Some highlights:
* Functions and values can have polymorphic types, inferred as part of a
  [Hindley-Milner type system](https://en.wikipedia.org/wiki/Hindley%E2%80%93Milner_type_system);
* Relational expressions may now include a `group` clause, so you can
  evaluate aggregate queries (similar to SQL `GROUP BY`);
* [Foreign values](https://github.com/hydromatic/morel/issues/5) allow external
  data, such as the contents of a JDBC database, to be handled as if it is in
  memory;
* Add built-in functions based on the
  [`String`](http://sml-family.org/Basis/string.html) and
  [`List`](http://sml-family.org/Basis/list.html) structures
  in the Standard ML basis library;
* [Postfix field reference syntax](https://github.com/hydromatic/morel/issues/9)
  makes Morel more familiar to SQL users;
* Add [Morel language reference](docs/reference.md).

### Features

* [[MOREL-15](https://github.com/hydromatic/morel/issues/15)]
  Improve pretty-printing: wrap long lines, and abbreviate long lists and deep
  structures
* [[MOREL-12](https://github.com/hydromatic/morel/issues/12)]
  In `from` clause, allow initializers to reference previous variables
* In `group`, `as alias` is optional
* [[MOREL-10](https://github.com/hydromatic/morel/issues/10)]
  Implicit labels in record expressions
* [[MOREL-9](https://github.com/hydromatic/morel/issues/9)]
  Allow `<expr>.<field>` as an alternative syntax for `#<field> <expr>`
* [[MOREL-7](https://github.com/hydromatic/morel/issues/7)]
  Rename project from 'smlj' to 'morel'
* [[MOREL-5](https://github.com/hydromatic/morel/issues/5)]
  Foreign values, including record values based on the contents of a JDBC schema
* [[MOREL-6](https://github.com/hydromatic/morel/issues/6)]
  Add `group` clause (and `compute` sub-clause) to `from` expression, to support
  aggregation and aggregate functions
* Polymorphic types
* Add `String` and `List` basis functions

### Bug-fixes and internal improvements

* [[MOREL-16](https://github.com/hydromatic/morel/issues/16)]
  Ensure that types derived for REPL expressions have no free type variables
* [[MOREL-14](https://github.com/hydromatic/morel/issues/14)]
  Tuple should equal record, and both equal `unit` when empty
* Add macros (special built-in functions that are 'called' at compile time to
  generate a new AST)
* Add `interface MutableEvalEnv`, for code that wants to mutate the last
  binding in an environment
* Make `EvalEnv` immutable
* Recursive functions in closures use the wrong environment
* Unit literal's `toString()` should be `()`, not `[]`
* For built-ins, add their alias to the compile-time environment
* In parallel declarations (`let` ... `and`) add variables to compilation
  environment
* Refactor special type constructors (list, tuple, record)
* [[MOREL-4](https://github.com/hydromatic/morel/issues/4)]
  `let fun` inside `from` expression fails
* Move built-in constants and functions into new `enum BuiltIn`
* In `Shell`, fix parsing single-quote in line comments, and line endings in
  multi-line statements

### Build and tests

* Test expressions used in documentation and blog posts
* Example of a user-defined aggregate function in a query
* Add a test with a temporary function in a query that takes a record-valued
  argument
* In `ScriptTest`, only load `Dictionary` if script is `foreign.sml`
* Enable some `group` tests
* Add `Sys_env ()` function, that returns the current environment
* Upgrade maven: 3.5.4 &rarr; 3.6.3
* Add maven wrapper jar
* Use correct `maven-javadoc-plugin` version
* Before launching repl, build test as well as main
* Convert `MainTest` to use fluent style
* In `Shell`, add optional pause, which seems to make `ShellTest` deterministic

### Site and documentation

* Add [Morel language reference](docs/reference.md)
* Add image to [README](README.md)
* Add [javadoc to site](http://hydromatic.net/morel/apidocs/)
* Generate an asciinema demo

## <a href="https://github.com/hydromatic/morel/releases/tag/smlj-0.1.0">0.1</a> / 2019-07-24

Initial release features the core language (primitive types, lists,
tuples, records; `let`, `if`, `fn` and `case` expressions; `val`,
`fun` and `datatype` declarations), an interactive shell `smlj`, and
relational extensions (`from`).
