Changelog

v0.34.0-rc1 - 2024-02-07

Language changes

Warn about function body not being used, because it already has external implementations for all targets.
It's now possible to compile a project with external functions that are not supported by the compilation target as long as those are not actually used.
The error message for when one imports a constructor instead of an homonymous type has been improved.

Language Server Changes

Added a View on HexDocs link on function hover.

Formatter

Fixed some quirk with the formatting of binary operators.
Fixed a bug where the formatter would move a function call's closed parentheses on a new line instead of splitting the function's arguments.
Now the formatter will format tuples as if they were functions, trying to first split just the last element before splitting the whole tuple.
Improved the formatting of multiline strings in string concatenation.

Build tool changes

The gleam new command now accepts any existing path, as long as there are no conflicts with already existing files. Examples: gleam new ., gleam new .., gleam new ~/projects/test.
The format for the README created by gleam new has been altered.
The gleam.toml created by gleam new now has a link to the full reference for its available options.
The gleam binary is now statically linked on Windows.
New projects are created requiring between versions of v0.34.0 inclusive and exclusive v2.0.0.
The repository section now supports additional VCS types in the form of codeberg, forgejo and gitea allowing a user, repo and additionally a host url.
TypeScript declaration for the prelude exports previously missing functions and classes. Additionally, swaps interfaces for classes and adds missing attributes to classes.
gleam commands now look in parent directories for a gleam.toml file.

Bug fixes

Fixed a bug where gleam add would not update manifest.toml correctly.
Fixed a bug where fn() { Nil }() could generate invalid JavaScript code.
Fixed a bug where the build tool would make unnecessary calls to the Hex API when path dependencies are used.
Fixed a bug where gleam new would generate a gitignore with build rather than /build.
Fixed where the types of generic constants could be incorrecly inferred.
Utf8Codepoint has been renamed to UtfCodepoint in prelude.d.mts.
Fixed a bug where gleam deps list would look in filesystem root instead of the current directory.
Fixed a bug with the isEqual function in prelude.js where RegExps were being incorrectly structurally compared and being falsely reported as being equal.
JavaScript: export from prelude.d.mts in gleam.d.mts to fix the error: "Type 'Result' is not generic".
Not providing a definition after some attributes is now a parse error.

v0.33.0 - 2023-12-18

v0.33.0-rc4 - 2023-12-17

The deprecated bit array options binary and bit_string have been removed.
The deprecated ambiguous type import syntax has been removed.
The deprecated BitString type has been removed.
The deprecated inspect functions and BitString type has been removed from the JavaScript prelude.

v0.33.0-rc3 - 2023-12-17

Formatter

The formatter now tries to split long chains of binary operations around the operator itself, rather than around other elements like lists or function calls.

Bug fixes

Fixed a bug where string prefix aliases defined in alternative case branches would all be bound to the same constant.

v0.33.0-rc2 - 2023-12-07

Language changes

The \e string escape sequence has been removed. Use \u{001b} instead.
Generated Erlang now disabled redundant case clause warnings as these are now redundant due to exhaustiveness checking.

Bug fixes

Fixed a bug where the \u string escape sequence would not work with on Erlang on the right hand side of a string concatenation.

v0.33.0-rc1 - 2023-12-06

Formatter

The formatter now tries to keep a function body and its arguments on a single line by first trying to split only its last argument on multiple lines.
Fixed a bug where the formatter would move comments out of blocks.
gleam format now ignores the Gleam build directory by default, even when not in a git repository.

Language changes

Gleam now has full exhaustiveness checking. Exhaustiveness issues have been downgraded from errors to warnings so that existing Gleam code can be upgraded to be exhaustive without breaking existing code. In a future version they will be upgraded to errors.
The ! operator can now be used in clause guards.
The words auto, delegate, derive, else, implement, macro, and test are now reserved for future use. If used they will emit a warning. In a future version this may be upgraded to an error.
The \u{...} syntax can be used in strings to specify unicode codepoints via a hexadecimal number with 1 to 6 digits.
The todo as and panic as syntaxes now accept an expression that evaluates to a string rather than just a string literal.

Build tool changes

The gleam run and gleam test commands gain the -t flag, which is an alias of the --target flag.
The gleam build, gleam check, gleam run and gleam test commands now also accept js and erl as values for the --target flag.
The gleam new command now creates packages at version 1.0.0.
The gleam publish command now asks for confirmation if the package being published is not yet version 1.0.0.
The gleam publish command now asks for confirmation if the package name is one that implies the package is maintained by the Gleam core team.
The error messages shown when dependency resolution fails have been improved.

Compiler WASM API

The WASM API for the compiler has been rewritten to be simpler.
The WASM API for the compiler now exposes warnings.

HTML documentation generator

Searching in rendered HTML documentation now also matches words that do not start with the input but do contain it.

Bug fixes

Fixed a bug where the JavaScript code generator could generate invalid code when pretty printing a zero arity function call when the line is over 80 columns wide.
Fixed a bug where the build directory could be left in an invalid state if there is Elixir code to compile and running on Windows without permission to create symlinks.
Fixed a bug where numbers with preceeding zeros could generate incorrect JavaScript.
The Erlang code generated by the /. operator no longer generates a warning for the upcoming negative zero float change in Erlang OTP 27.
Fixed a bug where using only types from an aliased import, wouldn't stop the compiler from emitting an unused alias warning for that import.
Fixed a bug where the formatter would remove the as name from string prefix patterns.
Fixed a bug where the formatter would misplace comments at the start of a block.
Fixed a bug where using a string prefix pattern in let assert would generate incorrect JavaScript.

v0.32.4 - 2023-11-09

Build tool changes

The build tool now supports rebar3 and mix hex packages where the package name differs from the otp application name.

bug fixes

Fixed a bug where invalid javascript code could be generated when a module function calls another function that was passed as an argument and the argument has the same name as the module function.
Fixed the target property of gleam.toml being ignored for local path dependencies by gleam run -m module/name

v0.32.3 - 2023-11-07

Language changes

Imported modules can now be discarded by giving them an alias starting with _.

Build tool changes

New projects are now generated with the call to gleam format coming last in the GitHub Actions workflow. This is so that feedback from tests is presented even if formatting is incorrect.
Added Windows support for the gleam export erlang-shipment command.

Bug fixes

Fixed a bug where some nested pipelines could fail to type check.

v0.32.2 - 2023-11-03

Build tool changes

New Gleam projects are created with gleam_stdlib v0.32 and gleeunit v1.0.

Bug fixes

Fixed a bug where gleam fix would not produce correct results for code that shadowed a prelude name with an import of the same name but a different kind.
Fixed a bug where documentation would not publish to Hexdocs for packages with a number in the name.
Fixed a bug where aliased unqualified types and values of the same name could produce an incorrect error.

v0.32.1 - 2023-11-02

Bug fixes

Fixed a bug where gleam fix would not produce correct results for code that shadowed a prelude name with an import of the same name but a different kind.
Fixed a bug where incorrect JavaScript could be generated due to backwards compatibility with the deprecated import syntax.

v0.32.0 - 2023-11-01

Bug fixes

Fixed a bug where running gleam fix multiple times could produce incorrect results.

v0.32.0-rc3 - 2023-10-26

Bug fixes

Fixed a bug where gleam fix would fail to update the deprecated type import syntax for aliased unqualified types.

v0.32.0-rc2 - 2023-10-26

Bug fixes

Fixed a bug where the backward compatibility for the deprecated import syntax could result in an import error with some valid imports.

v0.32.0-rc1 - 2023-10-25

Language changes

Using import module.{TypeName} to import a type has been deprecated, replaced by import module.{type TypeName}. In a future version of Gleam the old syntax will only import the value of the same name. Run gleam fix to update your code.
The BitString type has been renamed to BitArray. Run gleam fix to update your code.
The binary and bit_string bit array modifier have been deprecated in favour of bytes and bits.
The error message for when one element in a list doesn't match the others has been improved.
The error message for when the elements of a list's tail don't match the previous ones has been improved.
The error message for when one tries to access an unknown field has been improved.
The __gleam_prelude_variant__ property has been removed from the classes defined in the JavaScript prelude.
The deprecated todo("...") syntax has been removed.
Module access can now be used in case clause guards.
The JS target now supports bit syntax for module constants.
The Erlang compiler will no longer emit a duplicate warning for unused functions.
The @deprecated attribute can now be used with type definitions.
A warning is now emitted if a module alias is unused.

Language server changes

The language server now has a code action for removing unused items.
The language server now shows the type of variables defined using use on hover.

Build tool changes

The gleam check command supports the target flag.
The gleam fix command updates code to use BitArray rather than BitString.
The gleam fix command updates code to use the new import type syntax.
gleam fix sets the gleam version constraint in gleam.toml to >= 0.32.0.
The gleam version constraint field in gleam.toml now disregards pre and build components when checking for compatibility.
The prelude is no longer rendered once per package when compiling to JavaScript, instead one copy is rendered for the entire project. If you are using the gleam compile-package API you now need to give a path to the prelude using the --javascript-prelude flag.
The gleam export javascript-prelude and gleam export typescript-prelude commands have been added to export a copy of the prelude. This command may be useful for build tools that use the compiler via the gleam compile-package API.
Fixed a bug where some deprecation messages would not be printed.
The content has been made wider in rendered HTML documentation.
Dependencies that can be built with both mix and rebar3 are now built with mix if it exists on the system, and with rebar3 if it doesn't.

Bug fixes

"Compiling $package" is now only printed when a package has new changes to compile.
The main process started with gleam run no longer traps exits on Erlang.
The formatting of code in rendered HTML documentation has been improved.
The formatter no longer moves trailing comments out of custom type definitions.
Fixed a bug where some hexidecimal numbers would generate incorrect Erlang.
Fixed a bug where markdown tables would not render correctly in HTML documentation.
The float 0.0 is now rendered in Erlang as +0.0 to silence warnings in Erlang/OTP 27.

v0.31.0 - 2023-09-25

New Gleam projects are created with gleam_stdlib v0.31, actions/checkout v3.*, and erlef/setup-beam v1.*.
A note is included in the generated HTML documentation if a function is deprecated.

v0.31.0-rc1 - 2023-09-18

The @deprecated("...") attribute can be used to mark a function as deprecated. This will cause a warning to be emitted when the function is used.
A warning is now emitted if a module from a transitive dependency is imported.
Record access can now be used in case clause guards.
Fixed a bug where manifest.toml could contain absolute paths for path dependencies.
The as keyword can now be used to assign the literal prefix to a variable when pattern matching on a string.
The if conditional compilation, external fn, and external type syntaxes have been removed.
The description flag for the gleam new command has been removed.
The highlight.js grammar included with generated HTML documentation has been updated for the latest syntax.
Packages are no longer precompiled to Erlang when publishing to Hex if the package target is set to JavaScript.
An exception is now raised if JavaScript code uses the BitString class constructor and passes in the incorrect argument type.
Fixed a bug where mutually recursive functions could be incorrectly inferred as having an overly general type.
Fixed a bug where recursive type constructors could incorrectly infer a type error.
Fixed a bug where some mutually recursive functions would be inferred as having too general a type.
Fixed a bug where constants where not being correctly inlined when used in the size option of a bit string pattern match.
Fixed a bug where anonymous functions could parse successfully when missing a body.
Fixed a bug where incorrect unused variable warnings could be emitted for code that doesn't type check.
Fixed a bug where packages defaulting to the JavaScript target could have modules missing from their HTML documentation when published.
Corrected some outdated links in error messages.
Hovering over a function definition will now display the function signature, or the type of the hovered argument.
Use import type for importing types from typescript declarations.
Use .d.mts extension for typescript declarations to match .mjs.
Prefix module names with dollar sign in typescript to avoid name collisions.

v0.30.4 - 2023-07-26

External implementations are always referenced directly in generated code, to avoid the overhead of an extra function call.
Fixed a bug where the compiler could infer incorrect generic type parameters when analysing a module without type annotations with self recursive functions that reference themselves multiple times.

v0.30.3 - 2023-07-23

Fixed a bug where JavaScript module path such as node:fs would be rejected.
New Gleam projects are created with gleam_stdlib v0.30, Erlang OTP v26.0.2, Elixir v1.15.4, actions/checkout v3.5.1, and erlef/setup-beam v1.16.0.

v0.30.2 - 2023-07-20

Fixed a bug where the compiler could infer incorrect generic type parameters when analysing a module without type annotations with self recursive functions.
Fixed a bug where the formatter would incorrectly format external functions by breaking the return annotation instead of the function arguments.

v0.30.1 - 2023-07-13

Fixed a bug where the language server could fail to import path dependencies in monorepos.

v0.30.0 - 2023-07-12

A warning is now emitted for the deprecated external fn syntax.

v0.30.0-rc4 - 2023-07-10

An error is now emitted for invalid JavaScript external implementations.
Fixed a bug where Erlang external implementations could generate invalid code.

v0.30.0-rc3 - 2023-07-05

Fixed a bug where gleam fix would fail to parse command line flags.

v0.30.0-rc2 - 2023-07-03

Fixed a bug where gleam fix would merge external functions of the same name but incompatible types.
Fixed a bug where external function arguments would incorrectly be marked as unused.

v0.30.0-rc1 - 2023-06-29

The new @target(erlang) and @target(javascript) attribute syntax has been added for conditional compilation. The existing if conditional compilation syntax has been deprecated. Run gleam fix to update your code.
The new type TypeName syntax syntax replaces the external type TypeName syntax. The existing external type syntax has been deprecated. Run gleam format to update your code.
Adding a new dependency now unlocks the target package. This helps avoid failing to find a suitable version for the package due to already being locked.
A custom message can now be specified for panic with panic as "...".
The syntax for specifying a custom message for todo is now todo as "...".
The Erlang error raised by let assert is now tagged let_assert.
Types named Dynamic are now called dynamic_ in Erlang to avoid a clash with the new Erlang dynamic type introduced in OTP26.
Dependencies can now be loaded from paths using the packagename = { path = "..." } syntax in gleam.toml.
The javascript.deno.unstable field in gleam.toml can now be used to enable Deno's unstable APIs when targeting JavaScript.
Blockquotes are now styled in rendered HTML documentation.
The gleam property can be set in gleam.toml can be set to a version requirement to specify the version of Gleam required to build the project.
Type aliases can now refer to type aliases defined later in the same module.
Fixed a bug where unapplied record constructors in constant expressions would generate invalid Erlang.
Fixed a bug where the prescedence of <> and |> would clash.
Fixed a bug where gleam docs build would print an incorrect path upon completion.
Warnings from dependency packages are no longer surfaced in the language server.
A warning is now emitted when a Gleam file is found with an invalid name.
A warning is now emitted when using list.length to check for the empty list, which is slow compared to checking for equality or pattern matching (#2180).
The new gleam remove <package_name> can be used to remove dependencies from a Gleam project.
Fixed a bug where the formatter could crash.
Fixed a bug where invalid Erlang would be generated when piping into panic.
The gleam docs build command gains the --open flag to open the docs after they are generated (#2188).
Fixed a bug where type annotations for constants could not be written with type annotations.
Updated font loading in generated HTML documentation to fix an issue with fonts not loading properly in some browsers (#2209).

v0.29.0 - 2023-05-23

New projects now require gleam_stdlib v0.29.

v0.29.0-rc2 - 2023-05-22

The gleam lsp command is no longer hidden from the help output.
Fixed a bug where some language server clients would show autocompletion suggestions too eagerly.

v0.29.0-rc1 - 2023-05-16

The language server will now provide autocomplete suggestions for types and values either imported or defined at the top level of the current module.
Fixed a bug where record patterns using the spread operator (..) to discard unwanted arguments would not type check correctly when the record had no labelled fields.
Add support for using sized binary segments in pattern matches when targeting JavaScript.
A warning is now emitted for double unary negation on ints (--) and bools (!!) as this does nothing but return the original value.
Previously the build tool would discard the entire build directory when dependencies were changed. Now it will only discard the build artefacts for removed dependencies.
The errors emitted when a name is reused in a module have been made clearer.
Fixed an incorrect URL in the error message for failing to parse a let binding with a type annotation.
Fixed a bug where shadowing a prelude type name could result in incorrect errors in exhaustiveness checking.
Fixed a bug where the language server would in some scenarios not remove an error diagnostic after it becomes outdated.
Fixed a bug where the formatter would incorrectly format blocks with a comment before them that were the only argument to a function call.
Fixed a bug where the language server would not reset the build directory when it was created by a different version of Gleam.
New Gleam projects are created with erlef/setup-beam@v1.15.4 in their GitHub actions CI configuration.
Running a module now uses the dependency's target and runtime in its gleam.toml.

v0.28.3 - 2023-04-17

Fixed a bug where the language server would show outdated error diagnostics when a new one was emitted in a different module.
Fixed a bug where the language server would attempt to analyse Gleam modules that were outside of the src or test directories.
New Gleam projects are created with actions/checkout@v3.5.1 and erlef/setup-beam@1.15.3 in their GitHub actions CI configuration.

v0.28.2 - 2023-04-10

Fixed a bug where comments above a use expression would be formatted incorrectly.
Fixed a bug where the formatter would fail to preserve empty lines after a block.
Fixed a bug where the formatter would fail to preserve empty lines after an anonymous function with a return annotation.

v0.28.1 - 2023-04-05

Fixed a bug where the language server would unset too many error diagnostics when multiple projects are open, more than one have errors, and one of them is successfully compiled.
Fixed a bug where the language server would unset error diagnostics when displaying information on hover.
Added support for type annotations in use statements.

v0.28.0 - 2023-04-03

New projects now require gleam_stdlib v0.28.

v0.28.0-rc3 - 2023-03-31

Fixed a bug where source links would be incorrect in HTML documentation.

v0.28.0-rc2 - 2023-03-27

Fixed a bug where single statement blocks inside binary operators could generate invalid JavaScript.
Fixed a bug where the formatter could incorrectly place comments.
Fixed a bug where the language server would show outdated diagnostics when a file with an error reverts to the previous valid version, causing the compiler to use the cached version of the file.

v0.28.0-rc1 - 2023-03-26

The language server now analyzes files on edit rather than on save, providing feedback faster.
The language server now supports editor sessions that span multiple projects. This is useful for mono-repos and projects with both a frontend and backend in Gleam.
The language server now also shows documentation on hover for expressions.
The language server now shows types and documentation on hover for patterns.
Added support for negation of integers with the new - unary operator.
Variable assignments are now only permitted within a function or a block, not anywhere that an expression is permitted.
The deprecated try expression has been removed.
The deprecated assert ... = ... syntax has been removed.
Semicolons are no longer whitespace. An error will be emitted if one is encountered.
Warnings are now immediately emitted rather than being buffered until the end of the compilation.
The --warnings-as-errors flag is now supported by gleam build.
Blocks are now preserved by the formatter when they only have a single expression within them.
Generated docs now export more meta data to improve the developer experience, accessibility and search engine discoverability.
Files are now only recompiled if they have changed since the last compilation, detected by file hash and modification time. Previously only the modification time was used.
Autocompletion of module imports was removed due to a buggy implementation.
Fixed a bug where the formatter would incorrectly remove { ... } from bit string segment value expressions.
Fixed a bug where TypeScript type definitions files could include incorrect type names.
Fixed a bug where the compiler used VSCode specific behaviour in the language server which was incompatible with Helix.
Fixed a bug where string concatenation patterns on strings with escape characters would generate javascript code with wrong slice index.
Fixed a bug where blocks could parse incorrectly.
Allow modules to be run with the gleam run --module command.

v0.27.0 - 2023-03-01

Fixed a bug where panic could generate incorrect JavaScript code.
New projects now require gleam_stdlib v0.27.

v0.27.0-rc1 - 2023-02-26

The new panic keyword can be used to crash the program. This may be useful for situations in which a program has got into an unrecoverable invalid state.
try expressions are now deprecated and will be removed in a future version.
The new gleam fix command can be used to automatically convert try expressions to use expressions.
let assert ... = ... is now the syntax for assertion assignments. The assert ... = ... syntax is deprecated and will be removed in a future version. Run gleam format to automatically update your code.
gleam export hex-tarball can be used to create a tarball suitable for uploading to a Hex compatible package repository.
The unused private type and constructor detection has been improved.
The argument --runtime now accepts nodejs as the name for that runtime. The previous name node is still accepted.
Patterns can now be used in use expressions.
Fixed a bug where string concatenation patterns could generate javascript code with wrong slice index due to ut8/ut16 length mismatch.
The Erlang compiler will no longer emit a duplicate warning for unused variables.
Fixed a bug where typescript type definitions for types with unlabelled arguments where generated with an invalid identifier and unlabelled fields were generated with a name that didn't match the javascript implementation.
Fixed a bug in the type inferrer were unannotated functions that were used before they were defined in a module could in rare cased be inferred with a more general type than is correct.
Fixed a bug where the LSP would fail to show type information on hover for expressions after a use expression.
Fixed a bug where imported constants could generated incorrect JavaScript code.
Fixed a bug where the LSP would perform codegen for dependencies.
Fixed a bug where the LSP would compile native dependencies needlessly.
Fixed a bug where integer division with large numbers on JavaScript could produce incorrect results.
Fixed a bug where pattern matches on custom types with mixed labelled and unlabelled arguments could not be compiled when targeting JavaScript.
Fixed a bug where local variables in case guard constant expressions caused the compiler to panic.
The formatter now truncates meaningless zeroes of floats' fractional parts.
Anonymous functions may now have an empty body. The compiler will emit a warning for functions without a body, and these functions will crash at runtime if executed.
Fixed bug where raised errors on JS would have an extra stack frame recorded in them.

v0.26.2 - 2023-02-03

The formatter now wraps long | patterns in case clauses over multiple lines.
Fixed a bug where unlabelled function arguments could be declared after labelled ones.
A broken link was removed from the error messages.
Fixed a bug where using a qualified imported record constructor function as a value would produce invalid Erlang code if the name of the record variant was an Erlang reserved word.

v0.26.1 - 2023-01-22

New projects now require gleeunit v0.10.
Rebar3 dependency projects are now compiled in-place. This fixes an issue where some NIF using projects would fail to boot due to some paths not being copied to the build directory.
An error is now emitted if a list spread expression is written without a tail value.
An error is now emitted when a function is defined with multiple arguments with the same name.
The error message emitted when a let does not match all possible values has been improved.
Fixed a bug where the language server wouldn't analyse test code.
Fixed a bug where assert expressions can generate invalid Erlang. warning.
Fixed a bug where arguments would be passed incorrectly to Deno.
Fixed a bug where defining variables that shadow external functions could generate invalid JavaScript.

v0.26.0 - 2023-01-19

Release blog post

New projects require gleam_stdlib v0.26 and gleeunit v0.9.
Fixed a bug where JavaScript default projects would fail to publish to Hex.

v0.26.0-rc1 - 2023-01-12

Added support for Deno runtime for JavaScript target.
Scientific notation is now available for float literals.
The compiler now supports incremental compilation at the module level. If a module or its dependencies have not been changed then it will not be recompiled.
The format used by the formatter has been improved.
4 digit integers are now always formatted without underscores.
Running gleam new will skip git init if the new project directory is already part of a git work tree.
Generated HTML documentation now includes all static assets, including web fonts, so that it can be accessed offline and in future once CDNs would 404.
Generated HTML documentation now supports TypeScript syntax highlighting.
New Gleam projects are created using GitHub actions erlef/setup-beam@v1.15.2.
Some modules can now be hidden from the docs by specifying a list of glob patterns in internal_modules in gleam.toml. The default value for this list is ["$package_name/internal", "$package_name/internal/*"].
The gleam new command gains the --skip-git flag to skip creation of .git/*, .gitignore and .github/* files.
The gleam new command gains the --skip-github flag to skip creation of .github/* files.
Fixed a bug where no error would be emitted if a src module imported a test module.
Fixed a bug where comments in list prepending expressions could be formatted incorrectly.
Fixed a bug where comments in record update expressions could be formatted incorrectly.
Fixed a bug where long use expressions could be formatted incorrectly.
Fixed a bug integer multiplication would overflow large integers when compiling to JavaScript.
Fixed int and float formatting in consts and patterns.
Fixed a bug where piping into a function capture expression with a pipe as one of the arguments would produce invalid Erlang code.
Formatter no longer removes new lines in expression blocks within case branches

v0.25.3 - 2022-12-16

4 digit integers are no longer automatically formatted with underscores.

v0.25.2 - 2022-12-16

Updated actions/checkout from actions/checkout@v3.0.0 to @v3.2.0 for projects created via gleam new.
Fixed a bug where gleam new would set a Rebar3 version to 25.1 instead of the latest stable 3.
Updated following runtime versions set via gleam new: Erlang/OTP to 25.2, and Elixir to 1.14.2.
The formatter now inserts underscores into larger Ints and the larger integer parts of Floats.
Added support for top level TypeScript file inclusion in builds.
The build tool will now favour using rebar3 over Mix for packages that support both. This fixes an issue where some packages could not be compiled without Elixir installed even though it is not strictly required.

v0.25.1 - 2022-12-11

New Gleam projects are now configured to explicitly install rebar3 using GitHub actions erlef/setup-beam.
A better error message is now shown when attempting to use a function within a constant expression.
Changed float size limit in bit string expressions to 16, 32 or 64, when static. Also allowed dynamic size.
New Gleam projects are created using GitHub actions erlef/setup-beam@v1.15.0.
Fixed a bug where returning an anonymous function from a pipeline and calling it immediately without assigning it to a variable would produce invalid Erlang code.
Fixed a bug where the formatter would remove the braces from negating boolean expressions.

v0.25.0 - 2022-11-24

Release blog post

v0.25.0-rc2 - 2022-11-23

Fixed a bug where Gleam dependency packages with a priv directory could fail to build.
Fixed a regression where Elixir and Erlang Markdown code blocks in generated documentation would not be highlighted.

v0.25.0-rc1 - 2022-11-19

Generated HTML documentation now includes the theme-color HTML meta tag.
The use expression has been introduced. This is a new syntactic sugar that permits callback using code to be written without indentation.
Nightly builds are now also published as OCI container images hosted on GitHub.
Fixed a bug where the build tool would not hook up stdin for Gleam programs it starts.
Fixed a bug where using a record constructor as a value could generate a warning in Erlang.
Fixed a bug where the build tool would use precompiled code from Hex packages rather than the latest version, which could result in incorrect external function usage in some cases.
Fixed a bug where the warning for todo would not print the type of the code to complete.
Fixed a bug where try expressions inside blocks could generate incorrect JavaScript.
Generated HTML documentation now includes all static assets (but the web fonts), so that it can be accessed offline or in far future once CDNs would 404.
New Gleam projects are created using GitHub actions erlef/setup-beam@v1.14.0
The javascript.typescript_declarations field in gleam.toml now applies to the entire project rather than just the top level package.
The formatter now adds a 0 to floats ending with . (ie 1. => 1.0).
New projects require gleam_stdlib v0.25.

0.24.0 - 2022-10-25

Release blog post

0.24.0-rc4 - 2022-10-23

Fixed a bug where the string concatenate operator could produce invalid Erlang code when working with pipe expressions.

0.24.0-rc3 - 2022-10-20

Fixed a bug where the OOP method call error hint would be shown on too many errors.
Fixed a bug where the string concatenate operator could produce invalid Erlang code when working with constant values.

0.24.0-rc2 - 2022-10-18

Fixed a bug where imported and qualified record constructors used in constant expressions could fail to resolve.

0.24.0-rc1 - 2022-10-15

Gleam can now compile Elixir files within a project's src directory.
The <> operator can now be used for string concatenation and for string prefix pattern matching.
Fixed a bug where TypeScript definitions may have incorrect type parameters.
New projects depend on gleam_stdlib v0.24.
New projects' GitHub Actions config specifies Erlang/OTP 25.1 and suggest Elixir 1.14.1.
If you attempt to use the method call syntax (thing.method()) on a value without that field the error message will now include a hint explaining that Gleam is not object oriented and does not have methods.
Fixed a bug in the formatter where multiple line documentation comments for custom type constructor fields could be formatted incorrectly.
Fixed a bug where tail call optimisation could be incorrectly applied when compiling to JavaScript in some situations.
Fixed a bug where the remainder operator would return NaN results when the right hand side was zero when compiling to JavaScript.
Fixed a bug where Elixir dependencies would fail to compile on Windows.
Fixed a bug where images added to HTML documentation via documentation comments would not have a max width.

v0.23.0 - 2022-09-15

Release Blog Post

v0.23.0-rc2 - 2022-09-15

New Gleam projects are created using GitHub actions erlef/setup-beam@v1.13.0 and actions/checkout@v3.0.0.
New Gleam projects are created using version v0.23.0 of the stdlib.
Fixed a bug where LSP hovering would fail to locate the expression.

v0.23.0-rc1 - 2022-09-01

Gleam can now build dependency packages that are managed using Mix.
Compiler performance has been improved by buffering disc writing and by lazily loading TLS certs. In testing this doubles performance when compiling the standard library.
The gleam publish command now adds the priv directory and any NOTICE file to the tarball.
The gleam update command can now be used to update dependency packages to their latest versions.
Module functions with empty bodies are no longer syntax errors.
The format used by the formatter has been improved.
OpenSSL swapped out for RustTLS.
Generated HTML documentation now includes a search bar.
The LSP will now provide autocompletion for imports.
A helpful error message is now returned when assignments are missing either a keyword or a value.
Qualifiers are now used when multiple types have the same name in an error message.
In JavaScript, if an object has defined an equals method in its prototype, Gleam will now use this method when checking for equality.
Functions can now be defined and referenced in constant expressions.
An error is now raised if the record update syntax is used with a custom type that has multiple constructors.
An error is now raised if a module is imported multiple times.
Fixed a bug where defining a type named CustomeType would product invalid JavaScript.
Fixed a bug where defining a variable with the same name as an unqualified import would produce invalid JavaScript.
Fixed a bug where piping to todo would generate invalid Erlang code.
Fixed a bug where inspecting a JavaScript object with a null prototype would crash.
Fixed a bug where the formatter could crash if source code contained 3 or more empty lines in a row.
Fixed a bug where the formatter would remove braces from blocks used as the subject of a case expression.
Fixed a bug alternative patterns with a clause containing a pipe with a pipe after the case expresson could render incorrect Erlang.
Fixed a bug where formatter would strip curly braces around case guards even when they are required to specify boolean precedence.
Fixed a bug where gleam new would in some situations not validate the target directory correctly.
Fixed a bug where pipes inside record update subjects could generate invalid Erlang.
Fixed a bug where pipes inside record access could generate invalid Erlang.

v0.22.1 - 2022-06-27

The gleam publish confirmation prompt now accepts both "Y" and "y".
Fixed a bug where todo would not emit the correct line number to the LSP while.

v0.22.0 - 2022-06-12

Release Blog Post

New projects are created with gleam_stdlib v0.22.

v0.22.0-rc1 - 2022-06-12

Fixed a bug where doc comments would dissociate from their statements when generating html documentation.
You are now allowed to use named accessors on types with multiple constructors if the accessor's name, position and type match (among the constructors) (#1610).
Added the ability to replace a release up to one hour after it is published using gleam publish --replace.
gleam publish, gleam docs publish, gleam docs remove, gleam hex retire, and gleam hex unretire now have access to environment variables for username (default key HEXPM_USER) and password (default key HEXPM_PASS)
The gleam publish command gains the -y/--yes flag to disable the "are you sure" prompt.
Clear outdated files from the build directory after compilation.
Fixed a bug where immediately calling the value that a case expression evaluates to could generate invalid JavaScript.
Fixed a bug where the default project target is set to JavaScript, but the project would run on target Erlang instead.
The compiler is now able to generate TypeScript declaration files on target JavaScript (#1563). To enable this edit gleam.toml like so:
```
[javascript]
typescript_declarations = true
```
Fixed a bug where argument labels were allowed for anonymous functions.
Fixed a bug where JavaScript code could be invalid if a variable is defined inside an anonymous function with a parameter with the same name as the variable.
Fixed a bug where importing a JavaScript function named "then" could produce invalid code.
Fixed a bug where constants that reference locally defined custom types could render invalid JavaScript.
The project generator will no longer permit use of the reserved gleam_ prefix.
Generated HTML docs easter egg updated.
gleam export erlang-shipment can be used to create a directory of compiled Erlang bytecode that can be used as a deployment artefact to get your application live.
gleam format will now preserve (up to one) empty lines between consecutive comments, as well as between comments and any following expression
The deprecated rebar3 integration has been removed.
Fixed a bug where gleam format would output an unwanted newline at the top of documents that only contain simple // comments.
No longer add dev-dependencies to generated .app Erlang files unless we're compiling the root project (#1569).
Fixed a bug where the formatter could render a syntax error with lists on long unbreakable lines.
Fixed a bug where JavaScript variable names could be incorrectly reused.
Fixed a bug where gleam format would remove the braces around a tuple index access when accessing a field of the returned element.
Fixed a bug case clause guards could render incorrect JavaScript if a variable name was rebinded in the clause body.
The gleam compile-package command no longer generates a .app file. This should now be done by the build tool that calls this command as it is responsible for handling dependencies.
Fixed a bug where piping a list tail would create invalid Erlang code (#1656).

v0.21.0 - 2022-04-24

Release Blog Post

New projects are created with gleam_stdlib v0.21.

v0.21.0-rc2 - 2022-04-20

Added the ability to replace a release up to one hour after it is published using gleam publish --replace.
The language server will now enter a degraded mode that only performs formatting if running in a directory that is not a Gleam project with a gleam.toml.

v0.21.0-rc1 - 2022-04-16

The Gleam language server is here! This will provide IDE like features for code editors that support LSP, including but not limited to VSCode, Neovim, Emacs, Eclipse, Visual Studio, and Atom. This first version includes these features:
- Project compilation.
- Inline errors and warnings.
- Type information on hover.
- Go-to definition.
- Code formatting.
Fixed a bug in generated JavaScript code where functions named then would cause errors when dynamically imported.
Initialize git repo when creating a new project.
Log messages controlled with GLEAM_LOG now print to standard error.
Log message colours can be disabled by setting the GLEAM_LOG_NOCOLOUR environment variable.
You can now specify multiple packages when using gleam add.
Bools can now be negated with the ! unary operator.
If the compiler version changes we now rebuild the project from scratch on next build command to avoid issues arising from reading metadata in an old format (#1547).
Updated the "Unknown label" error message to match other error messages (#1548).
Type holes are now permitted in function arguments and return annotations (#1519).
Unused module imports now emit a warning (#1553).
The error message for failing to parse a multiline clauses without curly braces has been improved with a hint on how to fix the issue (#1555).
The error messages for when rebar3 or Erlang are missing from the machine has been improved with a tip on how to install them (#1567).
Corrected the hint given with certain int and float binary operator type errors.
Add support for int and float bit string type when compiling to JavaScript.
Add support for specifying size of integers in a bit string. Supports only exact binaries, i.e. length is a multiple of 8.
Fixed compilation of rebar3 based dependencies on Windows.

v0.20.1 - 2022-02-24

The type checker has been improved to enable use of the record access syntax (record.field) in anonymous functions passed into higher order functions without additional annotations.

v0.20.0 - 2022-02-23

Release Blog Post

New projects are created with gleam_stdlib v0.20.

v0.20.0-rc1 - 2022-02-20

Type unification errors involving user annotated types now refer to the names specified by the user instead of internal rigid-type ids.
The build tool now validates that listed licenses are valid SPDX expressions.
A WebAssembly version of the compile is now available for use in JavaScript and other WebAssembly environments.
New projects include Hex badges and a link to Hexdocs.
Enhance type mismatch errors in the presence of try.
Enhance type mismatch error for an inconsistent try.
Enhance type mismatch error for pipe expressions to show the whole pipeline and not only its first line.
Fixed a bug where sometimes type variable could be reused result in incorrect non-deterministic type errors.
Built in support for the Mix build tool has been removed. The mix_gleam plugin is to be used instead.
Introduce a limited form of exhaustiveness checking for pattern matching of custom types, which only checks that all constructor tags are covered at the top level of patterns.
The ebin directory is now copied to the build directory for rebar3 managed dependencies if present before compilation.
The format used by the formatter has been improved.
Package names in gleam.toml are validated when the config is read.
The priv directory is linked into the build directory for Gleam projects managed by the build tool.
Fixed a bug where type errors from pipes could show incorrect information.
Fixed a bug where types could not be imported if they had the same name as a value in the prelude.

v0.19.0 - 2022-01-12

Dedicated to the memory of Muhammad Shaheer, a good and caring man.

Release Blog Post

v0.19.0-rc4 - 2022-01-10

New projects are created with gleam_stdlib v0.19 and gleeunit v0.6.
Fixed a bug where external functions could be specified with the wrong module name in generated Erlang when imported from a nested module in another package.
Fixed a bug where warnings wouldn't get printed.

v0.19.0-rc3 - 2022-01-07

Fixed a bug where precompiled packages would fail to compile due to Erlang files being compiled twice concurrently.

v0.19.0-rc2 - 2022-01-06

Erlang modules are now compiled in a multi-core fashion.
New projects are created with erlef/setup-beam v1.9.0 instead of gleam-lang/setup-erlang and gleam-lang/setup-gleam.
Fixed a bug where tail call optimisation could generate incorrect code when the function has argument names that are JavaScript keywords.
Fixed a bug where the build would continue when dependency packages failed to compile.
Fixed a bug where include directories would not be accessible by the Erlang compiler during Gleam compilation.

v0.19.0-rc1 - 2022-01-03

The build tool now supports the JavaScript target. The target can be specified in either gleam.toml or using the --target flag.
The gleam check command has been introduced for rapidly verifying the types of Gleam code without performing codegen.
true and false can no longer be used as pattern matching variables, to avoid accidental uses of incorrect syntax that is popular in other languages. An error will hint about using Gleam's True and False values instead.
You can now remove build artifacts using the new gleam clean command.
The compile-package can now generate package.app files and compile source modules to .beam bytecode files.
The flags that compile-package accepts have changed.
Published Hex packages now include precompiled Erlang files.
Erlang record headers are now written to the include directory within the package build directory.
The format used by the formatter has been improved.
Fixed a bug where tail recursion could sometimes generated incorrect JavaScript code.
Performance of code generators has been slightly improved.
Allow the record in a record expansion to be an expression that returns a record.
Fixed a bug where external function module names would not be escaped correctly if they contained special characters and were assigned to a variable.
A helpful error message is shown if Erlang is not installed.

v0.18.2 - 2021-12-12

Erlang applications are now automatically started when the VM is started by gleam run and gleam test.

v0.18.1 - 2021-12-12

Fixed a bug where pipe expressions in record updates and operator expressions could generate incorrect Erlang code.
The priv directory is now copied to the output directory for rebar3 packages prior to compilation. This is required for some packages to compile.
Fixed a bug where deps that fail to compile would be skipped when compilation would next be attempted, resulting the project being in an invalid state.

v0.18.0 - 2021-12-06

Release Blog Post

New projects now include gleeunit.

v0.18.0-rc3 - 2021-12-05

URL format in gleam.toml is now validated.
The gleam deps list command has been added.
Fixed a bug where changing requirements in gleam.toml would not cause deps to be re-resolved.
Fixed a bug where locked deps would cause incompatible package requirements to be discarded.
Development dependencies are now included in the applications listed in the generated OTP .app file.
gleam.toml now includes an erlang.extra_applications key to specify extra OTP applications that need to be started.

v0.18.0-rc2 - 2021-11-26

Fixed a bug where OTP .app files would be generated with invalid syntax.
Removed extra whitespace from newly generated projects.

v0.18.0-rc1 - 2021-11-25

Gleam can now compile Gleam projects.
Gleam can now run tests with the gleam eunit command.
Gleam can now run programs with the gleam run command.
Gleam can now run an Erlang shell with the gleam shell command.
Gleam can now resolve package versions for a Gleam project's dependency tree.
Gleam can now download Hex packages.
Gleam can now build dependency packages that are managed using Gleam or rebar3.
Gleam is now the default build tool for new projects.
The template names for gleam new have been changed.
Fixed a bug where the error message for a record update with an unknown field would point to all the fields rather than the unknown one.
Improved styling for inline code in generated documentation.
New projects use v0.18 of the stdlib.

v0.17.0 - 2021-09-20

Release Blog Post

Functions now get special handling when being printed from JavaScript.

v0.17.0-rc2 - 2021-09-19

Errors thrown when no case clause or assignment pattern matches the subject value now include more debugging information when targeting JavaScript.
New projects are generated using gleam_stdlib v0.17.1.

v0.17.0-rc1 - 2021-09-11

Redesigned the Gleam prelude to be a module of core classes when compiling to JavaScript. This improves the resulting generated code and makes debugging and interop easier.
Projects without rebar3 can be generated using the gleam-lib template.
JavaScript modules are imported using a camel case variable name to avoid name collisions with variables.
Pipelines now use assignments in the generated code in order to preserve the order of any side effects.
Fixed a bug where the compiler would crash rather than raise an error if a project contained a single module and attempted to import another.
Special variable naming has been made more consistent in rendered Erlang and JavaScript.
Conditional compilation can now be used to have different code within a module when compiling to a specific target.
Fixed a bug where todo caused values not to be returned in JavaScript.
Fixed a bug where multiple discarded function arguments generated invalid JavaScript.
Fixed a bug where using JavaScript reserved words as function argument names caused generated invalid JavaScript.
Fixed a bug where a case expression of just a catch-all pattern generated invalid JavaScript.
Fixed a bug where the formatter would incorrectly render extra newlines below try expressions.
Fixed a bug where tail recursive functions with arguments with the same name as JavaScript reserved words generated the wrong JavaScript.
Fixed a bug where list equality would be incorrectly reported in JavaScript.
Multiple subjects are now supported for case expressions in JavaScript.
Fixed a bug where matching using a Bool or Nil literal as the subject for a case expression would produce invalid code when compiling to JavaScript.
Unsupported feature error messages now include file path and line numbers for debugging.
Bit string literals with no segment options or just the bit_string, utf8 or utf8_codepoint options can be constructed when compiling to JavaScript.
The format of generated JavaScript has been improved.
Fixed a bug where rendered JavaScript incorrectly incremented variables when reassigned in patterns.
Added eval and arguments to JavaScript reserved words.
Support for the deprecated tuple(x, y, ...) syntax has been removed in favor of the more concise (#(x, y, ...)). Use gleam format with the previous version of the compiler to auto-migrate.
New OTP projects are generated using gleam_otp v0.1.6.
Fixed a bug where the equality operators could return the incorrect value for records when compiling to JavaScript.
Fixed a bug where todo could sometimes render invalid JavaScript when used as an expression in the generated code.
An error is now emitted if the list spread syntax is used with no prepended elements [..xs].
Fixed a bug where type errors inside piped expressions would be incorrectly be reported as being an incorrect usage of the pipe operator.
Gleam modules with no public exports no longer render private members in Erlang.
Fixed a bug where discard variables used in assert assignments would generate invalid Erlang code.
Fixed a bug where some expressions as case subjects would generate invalid JavaScript code.
Fixed a bug where some assignments as the final expression in a function would not return the correct value in JavaScript.
Gleam packages imported in JavaScript now have the path prefix gleam-packages. This can be served from your web server or aliased in your package.json for NodeJS projects.
Fixed a bug where the type checker would fail to generalise some type variables, causing module metadata writing to fail.
Fixed a bug where tail call optimisation when compiling to JavaScript could result in incorrect code.
Fixed a bug where variable names could be rendered incorrectly in closures.
An error is now emitted if alternative patterns fail to define all the variables defined by the first pattern.
New projects are generated using gleam_stdlib v0.17.0.
New projects are generated using gleam_otp v0.2.0.

v0.16.1 - 2021-06-21

Values which are being imported more than once in an unqualified fashion now cause an error to be reported.
Argument docs for custom type constructors are now rendered in the HTML documentation.
Patterns can be used with try expressions when compiling to JavaScript.
Types and record constructors can now be aliased with an uppercase name when imported. Aliasing them with a lowercase name is no longer permitted.
Fixed a bug where nested import paths could be rendered incorrectly in JavaScript.

v0.16.0 - 2021-06-17

Release Blog Post

v0.16.0-rc4 - 2021-06-17

Fixed a bug where if a JavaScript global function was imported as an external function with the same name the generated code would diverge.

v0.16.0-rc3 - 2021-06-17

New projects are generated using gleam_stdlib v0.16.0.

v0.16.0-rc2 - 2021-06-08

Gleam now supports alternative patterns in case expressions for the JavaScript target.
The gleam prelude module can now be imported when compiling to JavaScript.
Fixed a bug where the prelude module could not be imported when using the old build compiler API.
Fixed a bug where if a JavaScript global function was imported as an external function with the same name the generated code would diverge.
Type error messages coming from pipe usage have been improved.

v0.16.0-rc1 - 2021-06-04

Gleam can now compile to JavaScript! Specify the --target javascript flag to gleam compile-package to use it today.
A compile time error is now raised when multiple module level constants with the same name are defined.
Fixed a bug where declaring a type constructor using reserved erlang keyword in its fields results in invalid erlang code being generated.
Fixed a bug where calling a function with discarded labelled arguments incorrectly results in a compile error.
Fixed a bug where assert statements return the wrong value.
The gleam new command requires a root folder param, project name is optional and if not provided the project name will be inferred from the folder name.
Generated Erlang record header files now contain Erlang type information.
New OTP application projects depend on gleam_otp v0.1.5.
The output of the formatter has been improved.

v0.15.1 - 2021-05-07

Fixed a bug where blocks that contained try expressions could be formatted incorrectly.

v0.15.0 - 2021-05-06

Release Blog Post

v0.15.0-rc1 - 2021-05-05

Syntax highlighting of Gleam code in generated HTML documentation has been improved.
Fixed a bug where markdown tables in rendered HTML documentation would have the incorrect background colour on every other row.
Tuples now have a new, concise syntax variant: #(x, y, ...). Existing code can be auto-migrated to the new syntax by running gleam format.
Fixed a bug where customt type constructors with Erlang keywords as names would generate invalid Erlang code.
Gleam now supports \e string escapes.
Values and types from the prelude can now be used in a qualified fashion by importing the gleam module.
Empty lists can now be used in constants.
Compiler performance has been improved when working with lists.
Compiler performance has been improved when working with sequences of expressions.
Assignments using let and assert are now expressions and no longer require a following expression in their containing block. They are now themselves expressions.
Fixed a bug where tuple indexing could incorrectly claim a tuple is not of type tuple in some circumstances.
Glean new command now checks if target folder exists, if so it returns an error.
A compile time error is now raised if a module is defined with the name gleam.
A compile time error is now raised if a module is defined with the a keyword in the name.
New projects are generated using gleam_stdlib v0.15.0.
New projects are generated at v0.1.0.

v0.14.4 - 2021-03-27

The Gleam compiler has been updated to compile with the new Rust v1.51.0.
New project's gleam.toml has a comment that shows how to add a repository field.
New projects no longer include a licence field in src/$APP.app.src by default.

v0.14.3 - 2021-03-20

Added an error hint when joining string using the + or +. operator.
New projects are created with setup-erlang v1.1.2 and Erlang/OTP v23.2.
Fixed a bug where the compiler would be unable to locate an imported module if a value from a nested module is used in a qualified fashion.

v0.14.2 - 2021-03-02

Project names can now contain numbers.

v0.14.1 - 2021-02-27

The error message for binary operators has been given more detail and hints.
Fixed a bug where alternative patterns would incorrectly report unused variables.
Fixed a bug where private types shadowed shadowed by values would incorrectly report unused variables.

v0.14.0 - 2021-02-18

Release Blog Post

v0.14.0-rc2 - 2021-02-18

New projects are created with gleam_stdlib v0.14.0.

v0.14.0-rc1 - 2021-02-14

Gleam now generates Erlang typespecs.
New projects no longer include a licence file by default.
New projects can be created using the new escript template to generate a command line tool style program.
A warning is emitted when a literal value is constructed but not used.
Automatically generate a link to repository in docs if available.
Code in HTML documentation is has highlighted syntax.
Gleam now only supports \r, \n, \t, \", and \\ string escapes.
A set of OCI container images are built automatically for each release.
New compile time checks for invalid bit string literals and patterns have been added.
The error messages for syntax errors in names have been improved.
Fixed a bug where the repo URL would render incorrectly in HTML docs.
Fixed a bug where piping a block can render invalid Erlang.
New compile time warnings on unused types, functions and variables.
The runtime error emitted by the todo keyword now carries additional information.
The runtime error emitted by the assert keyword now carries additional information.
Fixed a bug where bit string patterns would not correctly unify with the subject being pattern matches on.
Documentation dark mode.
Fixed a bug where some app.src properties were incorrectly named.
--warnings-as-errors flag added to gleam build command.

v0.13.2 - 2021-01-14

ring dep upgraded to enable compilation on Apple M1 ARM processors.

v0.13.1 - 2021-01-13

Fix off-by-one error in message messages.

v0.13.0 - 2021-01-13

Release Blog Post

New Gleam projects use stdlib v0.13.0.

v0.13.0-rc2 - 2021-01-12

The version property in gleam.toml is now optional again.

v0.13.0-rc1 - 2021-01-09

Variable names now only have 1st letter capitalized when converted to erlang.
Records defined in other modules can now be used in module constants.
Documentation can link from functions, types & constants to their source code definitions on popular project hosting sites.
Documentation hosted on HexDocs now has a version selector.
Fixed a bug where the app project template rendered invalid code.
Newly generated projects use stdlib v0.12.0.
Named subexpressions in patterns now render correct Erlang.
The anonymous function syntax now successfully parses with whitespace between fn and (.
Fixed a bug where the formatter would incorrectly remove blocks around some binary operators.
Constants can now be defined after they are used in functions
The parser has been rewritten from scratch, dramatically improving error messages and compilation times.
1-1 and a-1 are now parsed as 1 - 1 and a - 1
Further information has been added to the error messages when a function returns the wrong type.
Further information has been added to the error messages when case clauses return different types.
Fixed a bug where imported record constructors without labels used as an anonymous function generates incorrect Erlang.

v0.12.1 - 2020-11-15

The compiler can now discriminate between record access and module access for shadowed names
The new command will no longer permit projects to be made with names that clash with Erlang standard library modules.
The formatter now correctly treats lines of only whitespace as empty.
The styling of tables in rendered HTML documentation has been improved.
Rendered HTML documentation has regained its max-width styling.

v0.12.0 - 2020-10-31

Release Blog Post

v0.12.0-rc4 - 2020-10-31

The rendered module documentation sidebar can now scroll independently to the page.
Application projects now have the correct mod value in the generated .app.src.
Records without fields can now be used in module constants.
New application projects are now created used Gleam's type safe OTP pulled from Hex.

v0.12.0-rc3 - 2020-10-24

v0.12.0-rc2 - 2020-10-24

v0.12.0-rc1 - 2020-10-24

The utf8, utf16, and utf32 type specifiers are now only available in bit string construction, matching must be done with the codepoint versions.
Functions may now be called before they are defined in a module. This enabled mutually recursive functions!
Discarded variable names may now include numbers.
Fixed a bug where discarded variables might generate incorrect Erlang.
Added support tuple access in clause guards.
New projects are created with version 1.0.2 of the setup-gleam GitHub action.
New application projects are now created used Gleam's type safe OTP.
Comments are now correctly handled on platforms that use \r\n line endings, such as Windows.

v0.11.2 - 2020-09-01

Fixed a bug where an imported constructor would emit an unused constructor warning when only used in pattern matching.

v0.11.1 - 2020-08-31

The formatter style has been improved to render function type arguments on a single line when possible, even if the return type will not fit on a single line.
The format for printed types in error messages has been improved.
Fixed a bug where the formatter would strip a constructor pattern spread when no fields are given.
Fixed a bug where assigning the result of a block to a variable would generate incorrect Erlang.
The formatter style has been improved for function calls that take a single block as an argument.
Reserved words are no longer incorrectly permitted as project names.

v0.11.0 - 2020-08-28

Release Blog Post

v0.11.0-rc3 - 2020-08-27

Bit strings now support non-literal strings as segment values.
Fixed a bug where Erlang variables could be generated with incorrect names when defining an anonymous function.

v0.11.0-rc2 - 2020-08-24

The formatter style has been improved to render some single argument calls in a more compact style.

v0.11.0-rc1 - 2020-08-22

Field access now works before the custom type is defined.
The error message returned by the compiler when the user tries to use unknown labelled arguments now handles multiple labels at once, and does not suggest labels they have already supplied.
The formatter style has been improved to use a trailing comma on imports broken over multiple lines.
The formatter style has been improved to wrap lists and bit strings over as few lines as possible if the elements are Ints, Floats, or Strings.
The formatter style has been improved to preserve comments on labelled call arguments.
The formatter style has been improved to preserve empty lines in assignments.
The performance of the formatter has been improved.
Records can be updated using the spread syntax. A warning is emitted if no fields are updated when using this syntax.
Fixed a bug where type parameters can leak between different type definitions in a module.
Markdown tables, footnotes, strikethroughs, and tasklists are now supported in documentation.
Fixed a bug where generic types may be incorrectly unified.
Ints and floats can now be written with underscores for clarity.
The warning for a todo now includes the required type of the not-yet-implemented expression.
Holes can be used in type annotations to specify part of a type, leaving the rest for inference.
The incorrect arity error now prints any missing labelled arguments.
Fixed a bug where Erlang variables could be generated with incorrect names when directly calling an anonymous function.
A warning is emitted when a type is imported or created but not used.
Fixed a bug where Erlang variables names could clash when rebinding variables while similarly named variables ending in a number are in scope.
Fixed a bug in the pretty printer which prevented the formatter from rendering sub-expressions in a single line when later code would not fit on the same line.
The formatter style has been improved to render some single argument calls in a more compact style.
Gleam now supports hex, octal, and binary literals.
Rebar3 hex packages now include gleam.toml and gen.
Newly generated projects use stdlib v0.11.0.

v0.10.1 - 2020-07-15

Fixed a bug where the compiler failed to return an error when type checking a tuple with the wrong arity in a pattern.
The error message for a duplicate module member now shows the location of both definitions.
Fix compiler bug where labelled arguments were being reordered incorrectly.

v0.10.0 - 2020-07-01

Release Blog Post

Newly generated projects use stdlib v0.10.1.
Fixed a bug where discards inside bit string patterns generated invalid code.

v0.10.0-rc2 - 2020-06-30

Fixed a bug where variables names would be incorrectly generated when using alternative patterns.

v0.10.0-rc1 - 2020-06-29

Single letter module names are now permitted.
Added support for bit string syntax.
Support for the deprecated list prepend syntax has been removed.
Added module level constants that are inlined at compile time.
Public module level constants generate documentation.
The formatter style has been improved to wrap and sort imports.
The formatter now permits comments at the end of module function bodies.
The formatter now skips files that match patterns defined in ignore files such as .gitignore and .ignore.
Error message diagnostic code previews for type errors when using the the pipe operator have been made more accurate.
Added support for list literals in clause guards.
Fixed bug when reassigning a variable inside a case clause with alternative patterns.
Todos can now take an optional label.

v0.9.1 - 2020-06-12

Fixed a bug where binary operators may lose required { }s when formatted.

v0.9.0 - 2020-06-01

Release Blog Post

Newly generated projects use stdlib v0.9.0.
Additional information is printed to the console when generating HTML documentation from Gleam code.
Fixed a bug where blocks on either side of a binary operator would be rendered without { }.

v0.9.0-rc1 - 2020-05-26

The formatter style has been improved.
Numbers are now permitted in module names.
Emitted Erlang code correctly adds parentheses around binary subexpressions to preserve precedence.
Record names and fields are now escaped in .hrl files if they conflict with Erlang reserved words
Annotations are now supported on let and assert expressions
Formatter now accepts comments for the fields of a custom type's constructors
Added opaque custom types, which have constructors that cannot be accessed from outside their own modules.
Additional (arbitrary) markdown documentation pages can now be added and built with docs build.
Fix code generation when calling functions returned through either record or tuple access
Add lookup for Gleam source code in Mix's deps directory.
Newly generated Gleam projects use the GitHub action gleam-lang/setup-erlang v1.1.0.
Added support for custom type record literals in guards.
Type variables are now correctly preserved within nested scopes.

v0.8.1 - 2020-05-19

The formatter now correctly handles unicode comments.

v0.8.0 - 2020-05-07

Release Blog Post

The docs build, docs publish, and docs remove commands can be used to compile HTML documentation locally, publish them to HexDocs, and remove them from HexDocs respectively.
Type error reporting has been improved when using the pipe operator.
Newly generated projects use stdlib v0.8.0.
The compiler can now emit warnings. Currently there are warnings for using the old '|' syntax in lists and for todos.
Will give a clearer error when a function given as an argument to another function doesn't match the type of the parameter.
Fixed bug where imported type constructors had the incorrect arity.
Fixed bug where a doing an unqualified import of a type constructor and giving it an alias would use the wrong name if it contained any values.
Fixed a bug trying to access an imported constructor which contained values.
Fixed a compiler crash that occurred when trying to unify a tuple with something other than another tuple or a variable.
Added support for tuple literals in guards.

v0.8.0-rc1 - 2020-04-28

Strings are now encoded as utf8 binaries in the generated Erlang.
HTML documentation can now be generated from Gleam code by running gleam build --doc.
Gleam code can be formatted using the gleam format command.
The pipe operator |> will now attempt to insert the left hand side as the first argument to the right hand side if the right hand side is a call, removing the need for function capture boilerplate.
A record.label syntax can now be used to access the fields of a custom type that have a single record variant.
Anonymous functions can now have return type annotations.
There is a todo keyword for type checking functions that have not yet been implemented.
Tuples can be indexed into using the var.1 syntax.
>, >=, <, and <= operators are now supported in case clause guards and can be used to check the ordering of integers.
>., >=., <., and <=. operators are now supported in case clause guards and can be used to check the ordering of floats.
The list prepend syntax is now [x, ..y]. The old [x | y] syntax is deprecated but will continue to work for now. The formatter will rewrite the old syntax to the new.
Add new assert syntax for binding variables assert Ok(x) = result. In the future this will allow you to use a pattern that does not match all values.
Added support for int and float literals in guards.
Color codes are now only emitted in error output for interactive terminal sessions.
Added a new .. syntax for discarding the remaining fields of a record.
Using the same variable name multiple times in the same pattern will now raise an error.
Discard can now be omitted in list tails in patterns, ie [x, ..] is the same as [x, .._]. The former is the preferred version and is emitted by the formatter.

v0.7.1 - 2020-03-03

Projects generated with gleam new use stdlib version 0.7.0.

v0.7.0 - 2020-03-01

Release Blog Post

v0.7.0-rc1 - 2020-02-28

Type aliases can be defined to give concise names to frequently used types.
Case expression clauses may have guards which can be used to require equality between specified variables in order for the clause to match.
Case expression clauses may have alternative patterns, enabling one clause to match for multiple different possible patterns.
Types may now be used before they are defined within their defining module.
Fixed a bug where import paths would not be correctly resolved on Windows.
Added job to create precompiled binary for 64-bit Windows when releasing.
gleam new now creates a project that uses actions/checkout@v2.0.0 in its GitHub actions workflow.
Labelled argument in functions may now be discarded by prefixing the name with an underscore, like unlabelled arguments.
Sub-patterns can have names assigned to them within a pattern using the as keyword.
The format of compiler error messages printed to the console has been improved by upgrading to a newer version of the codespan-reporting library.
Type variables in the given and expected types will now be printed with the same name in type error messages if they are equivalent.
A friendly error message is rendered when a case expression clause has the incorrect number of patterns for the subjects.
A friendly error message is rendered when a .gleam file cannot be read.
A friendly error message is rendered when the gleam new command fails to write the new project to the file system.
A friendly error message is rendered when there is a cycle formed by module imports.
Top level types are now printed in error messages for type parameter mismatches.
The gen directory is now deleted before each compilation.
gleam new now includes installation instructions for Hex packages in the generated README.
gleam new now accepts a --description flag for including a description of the project in the README and .app.src file.
Fixed a bug where variable names would be incorrectly generated in some situations when variable names are reused during and after a case expression.
Performance of the Erlang code generator has been improved by removing some vector allocations.
An error is emitted when multiple types with the same name are defined in or imported into a module.

v0.6.0 - 2019-12-25 🎄

Release Blog Post

Function capture syntax now supports labelled arguments.

v0.6.0-rc1 - 2019-12-23

Syntax for defining structs and enums have been unified into a singular custom type definition statement. Instances of these custom types are called records.
Anonymous structs have been renamed tuples.
Values and types can be given a new name when imported in the unqualified fashion using the import mod.{value as name} syntax.
An error will be emitted if multiple values constructors are defined with the same name in a module.

v0.5.1 - 2019-12-23

Fixed a bug where invalid Erlang would be generated when using a local private function as a value.

v0.5.0 - 2019-12-16

Release Blog Post

Enum constructor arguments can now be labelled, allowing arguments to be given by name at the call site.
An Erlang header file with a record definition is generated for each Gleam struct defined.
gleam new creates a project at v1.0.0.
Function calls are now properly escaped when the function name conflicts with an Erlang keyword.
References to unqualified imported functions now generate correct Erlang code.
Fixed a bug where variable rebinding would generate incorrect code in some case expressions.
Fixed a bug where variable rebinding of function arguments would generate incorrect code.

v0.5.0-rc1 - 2019-11-26

Function arguments can be labelled, allowing arguments to be given by name at the call site.
case expressions now accept multiple subjects, enabling pattern matching on multiple values simultaneously.
Values and types can be imported from modules and references in an unqualified fashion.
Named structs now have their name as the first element in the generated Erlang code. This enabled easier use from Erlang by defining records for them, as well as slightly clearer printf debugging.
Anonymous structs have been introduced, serving as a quick and generic alternative to declared structs and as a format for interop with Erlang tuples.
gleam new now accepts a --template flag to generate different styles of project. An OTP application template has been added alongside the existing OTP library template.
gleam new now creates configuration for GitHub Actions, making Gleam projects ready for continuous integration out of the box.
The syntax for defining enums, case expressions, and blocks has been changed to a syntax closer to that found in the C family of languages.
The source code preview for functions that return a type incompatible with the functions annotations has been improved to be more precise.
A helpful error message is rendered if an enum field contains a generic type that has not been declared.
A bug has been fixed in which type mismatch errors originating from pattern matching would sometimes display the incorrect expected type.

v0.4.2 - 2019-10-22

Fixed a crash when an incorrect number of labelled struct arguments are given.
Fixed a struct labelled argument being incorrect reported as already given.

v0.4.1 - 2019-09-29

Struct types with parameterised fields are now registered with the correct number of type parameters.

v0.4.0 - 2019-09-19

Release Blog Post

The struct data type has be introduced. Structs are pre-declared user defined data types with named fields and constant access time.
The map and tuple data types has been removed, replaced by the struct data type.
The generated code no longer contains export statements if no functions are exported from a module.
Comparison operators have been specialised to operate only on Ints.
The >. >=. <. and <=. comparison operators have been added for comparing Floats.
It is now an error to export an enum which has a constructor that takes a private type as an argument.
The error messages for defining multiple modules with the same name and for importing test modules into application code have been improved.
Numbers are now permitted in type names and constructors.
The Nil constructor will no longer erroneously be of type Int.

v0.3.0 - 2019-08-08

Release Blog Post

New project structure can be generated with the gleam new command.
Functions can be annotated with their argument and return types. This may be used to restrict the function to a less general type than inferred by the compiler, or purely for documentation purposes.
External function names and their target functions are now escaped in the generated code if they collide with Erlang keywords such as catch or or.
Type error arising from the arguments of function calls have more accurate error diagnostics.
Precompiled Gleam binaries are now available on the GitHub release page.
Precompiled Docker images containing the Gleam binary are now available on DockerHub.
The formatting of the Erlang code rendered by the compiler has been altered to improve legibility.
A helpful error message is now rendered if the shorthand anonymous function syntax is used with too many underscores.
A helpful error message is now rendered when attempting to import an unknown module.

v0.2.0 - 2019-06-25

Modules can now live within namespaces such as my_app/user/profile.
The name of the variable created can be specified when importing a module using the import my_mod as name syntax.
Function names and atoms are now escaped in the generated code if they collide with Erlang keywords such as catch or or.
There is a shorthand syntax for prepending multiple elements to a list. [1, 2, 3 | my_list]

v0.1.2 - 2019-05-12

Types containing more than 26 type variables will no longer render with invalid type variable names.
Types in error messages no longer have extra indentation that increases as the type gets larger.
There is a new type Nil which is occupied by a single value (Nil). This type is used to represent the absence of a value and is commonly used with Result to model a value that is either present (Ok(value)) or absent (Error(Nil)).
Zero arity enum constructors now generate the correct Erlang when used in modules other than the one they are defined in.

v0.1.1 - 2019-04-28

Error messages now display the path of the file containing the problem.
Maps and modules with erroneous extra fields now have a custom error message.
Rows with tails that are unbound type variables are now correctly unified in the type system. This fixes a bug in which maps and modules may sometimes fail to type check when there is no error.

v0.1.0 - 2019-04-15

Release Blog Post

Initial release!

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v0.34.0-rc1 - 2024-02-07

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v0.33.0 - 2023-12-18

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v0.33.0-rc2 - 2023-12-07

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v0.32.4 - 2023-11-09

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v0.32.2 - 2023-11-03

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v0.32.1 - 2023-11-02

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v0.32.0 - 2023-11-01

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v0.32.0-rc3 - 2023-10-26

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v0.32.0-rc2 - 2023-10-26

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v0.32.0-rc1 - 2023-10-25

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v0.31.0 - 2023-09-25

v0.31.0-rc1 - 2023-09-18

v0.30.4 - 2023-07-26

v0.30.3 - 2023-07-23

v0.30.2 - 2023-07-20

v0.30.1 - 2023-07-13

v0.30.0 - 2023-07-12

v0.30.0-rc4 - 2023-07-10

v0.30.0-rc3 - 2023-07-05

v0.30.0-rc2 - 2023-07-03

v0.30.0-rc1 - 2023-06-29

v0.29.0 - 2023-05-23

v0.29.0-rc2 - 2023-05-22

v0.29.0-rc1 - 2023-05-16

v0.28.3 - 2023-04-17

v0.28.2 - 2023-04-10

v0.28.1 - 2023-04-05

v0.28.0 - 2023-04-03

v0.28.0-rc3 - 2023-03-31

v0.28.0-rc2 - 2023-03-27

v0.28.0-rc1 - 2023-03-26

v0.27.0 - 2023-03-01

v0.27.0-rc1 - 2023-02-26

v0.26.2 - 2023-02-03

v0.26.1 - 2023-01-22

v0.26.0 - 2023-01-19

v0.26.0-rc1 - 2023-01-12

v0.25.3 - 2022-12-16

v0.25.2 - 2022-12-16