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Fork of daniellemaywood.uk/gleam — Wasm codegen work
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1<!--
2 SPDX-License-Identifier: Apache-2.0
3 SPDX-FileCopyrightText: 2020 The Gleam contributors
4-->
5
6# Changelog
7
8## v1.18.0-rc2 - 2026-07-25
9
10### Bug fixes
11
12- Fixed a bug where the compiler would crash when wrapping an error message
13 whose line broke in the middle of a multi-byte UTF-8 character.
14 ([John Downey](https://github.com/jtdowney))
15
16- Fixed a bug where invalid JavaScript would be generated for code which used a
17 bit array pattern to extract a `Float` and had a constructor called `Number`.
18 ([Surya Rose](https://github.com/GearsDatapacks))
19
20- Fixed a bug where `-0.0` would be encoded incorrectly in 16-bit bit array
21 segments on the JavaScript target.
22 ([Surya Rose](https://github.com/GearsDatapacks))
23
24- Fixed a bug where the formatter would insert underscores into negative
25 hexadecimal, octal, and binary literals, producing code that no longer
26 compiles.
27 ([John Downey](https://github.com/jtdowney))
28
29- Fixed a bug where type annotations on discarded variables in `use` bindings
30 were ignored.
31 ([Francesco Cappetti](https://github.com/frakappa))
32
33- Fixed a bug where the language server would crash on code that contains syntax
34 errors.
35 ([Giacomo Cavalieri](https://github.com/giacomocavalieri))
36
37- Fixed a bug where bit array segments would not be compiled properly, using an
38 invalid Erlang segment option.
39 ([Giacomo Cavalieri](https://github.com/giacomocavalieri))
40
41## v1.18.0-rc1 - 2026-07-21
42
43### Compiler
44
45- The compiler now issues a friendlier error when attempting to pattern match
46 on both the prefix and suffix of a string:
47
48 ```
49 error: Syntax error
50 ┌─ /src/parse/error.gleam:2:23
51 │
52 2 │ "prefix" <> infix <> "suffix" -> infix
53 │ ^^^^^^^^^^^ This pattern is not allowed
54
55 A string pattern can only match on a literal string prefix.
56
57 Matching on a literal suffix is not possible, because `infix` would have an
58 unknown size.
59 ```
60
61 ([Gavin Morrow](https://github.com/gavinmorrow))
62
63- Improved the error message shown when using an invalid discard name for
64 functions, constants, module names, and `as` patterns.
65 ([Giacomo Cavalieri](https://github.com/giacomocavalieri))
66
67- The compiler now generates singleton values for variants with no fields on the
68 JavaScript target, allowing for faster comparison in most cases.
69 ([Surya Rose](https://github.com/GearsDatapacks))
70
71- The use of pipes to turn the Gleam code `a |> b(c)` into `b(c)(a)` has been
72 deprecated.
73 ([Surya Rose](https://github.com/GearsDatapacks))
74
75- The compiler now gives a better error message when an `@external`
76 attribute is incomplete. For example:
77
78 ```gleam
79 @external
80 pub fn wibble()
81 ```
82
83 now points to the attribute itself and explains that it is incomplete.
84 ([Asish Kumar](https://github.com/officialasishkumar))
85
86- The "did you mean one of these:" hint is now phrased in singular when there
87 is only one suggestion, additionally multiple suggestions are listed
88 in a consistent alphabetical order.
89 ([Zbyněk Juřica](https://github.com/zbyju))
90
91### Build tool
92
93- The build tool now generates Hexdocs URLs using the new format of
94 `package.hexdocs.pm` rather than `hexdocs.pm/package`.
95 ([Surya Rose](https://github.com/GearsDatapacks))
96
97- More readable error message when trying to revert an old release.
98 ([Moritz Böhme](https://github.com/MoritzBoehme))
99
100- The build tool now includes destination path in the error when it fails to
101 link or copy file or directory.
102 ([Andrey Kozhev](https://github.com/ankddev))
103
104- Git dependencies now support an optional `path` field to specify a
105 subdirectory within the repository. This is useful for monorepos that
106 contain multiple Gleam packages. For example:
107
108 ```toml
109 [dependencies]
110 my_package = {
111 git = "https://github.com/example/monorepo",
112 ref = "main",
113 path = "packages/my_package",
114 }
115 ```
116
117 ([John Downey](https://github.com/jtdowney))
118
119- The `gleam hex owner transfer` command now uses the flag `--user` instead of
120 the flag `--to`. The `gleam hex owner add` command now takes the package name
121 via the flag `--package`.
122 ([Louis Pilfold](https://github.com/lpil))
123
124- The error message when failing to decrypt the local Hex API key is now more
125 informative and helpful.
126 ([Moritz Böhme](https://github.com/MoritzBoehme))
127
128- The build tool can now authenticate requests to Hex with the API key from the
129 `HEXPM_READ_API_KEY` environment variable, when resolving and downloading
130 dependencies. This raises the request rate limit from the stricter per-IP
131 limit to the higher per-user limit, avoiding "rate limit exceeded" errors
132 when building large projects.
133 ([John Downey](https://github.com/jtdowney))
134
135### Language server
136
137- The language server now supports go-to-definition, find-references and rename
138 for record fields. These work on the field declaration, on labelled arguments,
139 on labelled patterns, on record updates and on `record.field` accesses, both
140 within a module and across modules. For example:
141
142 ```gleam
143 pub type Person {
144 Person(name: String, age: Int)
145 }
146
147 pub fn main() {
148 let lucy = Person(name: "Lucy", age: 10)
149 lucy.name
150 // ^ Go-to-definition jumps to the `name` field, and renaming it here
151 // renames the field everywhere it is used.
152 }
153 ```
154
155 ([Alistair Smith](https://github.com/alii))
156
157- The "pattern match on value" code action can now be used to pattern match on
158 values returned by function calls. For example:
159
160 ```gleam
161 pub fn main() {
162 load_user()
163 // ^^ Triggering the code action over here
164 }
165
166 fn load_user() -> Result(User, Nil) { todo }
167 ```
168
169 Will produce the following code:
170
171 ```gleam
172 pub fn main() {
173 case load_user() {
174 Ok(value) -> todo
175 Error(value) -> todo
176 }
177 }
178 ```
179
180 ([Giacomo Cavalieri](https://github.com/giacomocavalieri))
181
182- The language server now offers a code action to rewrite integers in a
183 different base. For example:
184
185 ```gleam
186 pub fn lucky_number() {
187 0b1011
188 //^^^^^^ Hovering this
189 }
190 ```
191
192 The language server is going to show code actions to rewrite it as `11`,
193 `0o13`, or `0xB`.
194 ([Giacomo Cavalieri](https://github.com/giacomocavalieri))
195
196- The "remove unreachable patterns" code action can now be triggered on
197 unreachable alternative patterns of a case expression.
198 ([Giacomo Cavalieri](https://github.com/giacomocavalieri))
199
200- The language server now permits renaming type variables in functions, types,
201 and constants. For example:
202
203 ```gleam
204 pub fn twice(value: a, f: fn(a) -> a) -> a {
205 // ^ Rename to "anything"
206 f(f(value))
207 }
208 ```
209
210 Produces:
211
212 ```gleam
213 pub fn twice(value: anything, f: fn(anything) -> anything) -> anything {
214 f(f(value))
215 }
216 ```
217
218 ([Surya Rose](https://github.com/GearsDatapacks))
219
220- The language server now automatically updates imports when a Gleam module is
221 renamed. For example:
222
223 ```gleam
224 import db_users
225
226 pub fn main() -> db_users.User {
227 db_users.new("username")
228 }
229 ```
230
231 Renaming `db_users.gleam` to `database/user.gleam` would produce:
232
233 ```gleam
234 import database/user
235
236 pub fn main() -> user.User {
237 user.new("username")
238 }
239 ```
240
241 ([Surya Rose](https://github.com/GearsDatapacks))
242
243- The language server now offers a code action to generate a missing type
244 definition when an unknown type is referenced. For example, if `Wibble`
245 is not defined:
246
247 ```gleam
248 pub fn run(data: Wibble(Int)) { todo }
249 ```
250
251 The code action will generate:
252
253 ```gleam
254 pub type Wibble(a)
255
256 pub fn run(data: Wibble(Int)) { todo }
257 ```
258
259 ([Daniele Scaratti](https://github.com/lupodevelop))
260
261- The language server now has "Discard unused variable" code action to discard
262 unused variables in different places. For example,
263
264 ```gleam
265 pub type Wibble {
266 Wibble(a: Int)
267 }
268
269 pub fn go(record: Wibble) -> Nil {
270 let wibble = 0
271 // ^ Trigger code action here
272
273 case record {
274 Wibble(a:) -> Nil
275 // ^ Trigger code action here
276 }
277
278 case [0, 1, 2] {
279 [_, ..] as wobble -> Nil
280 // ^ Trigger code action here
281 [] -> Nil
282 }
283
284 Nil
285 }
286 ```
287
288 Triggering the code action in all of these places would produce following code:
289
290 ```gleam
291 pub type Wibble {
292 Wibble(a: Int)
293 }
294
295 pub fn go(record: Wibble) -> Nil {
296 let _wibble = 0
297
298 case record {
299 Wibble(a: _) -> Nil
300 }
301
302 case [0, 1, 2] {
303 [_, ..] -> Nil
304 [] -> Nil
305 }
306
307 Nil
308 }
309 ```
310
311 ([Andrey Kozhev](https://github.com/ankddev))
312
313- The language server will now better rename types and values with import
314 aliases by removing `as ...` part in case new name is same as original name of
315 item. For example:
316
317 ```gleam
318 import wibble.{type Wibble as Wobble, Wibble as Wobble}
319
320 pub fn go() -> Wobble {
321 // ^^^^^^ Rename to `Wibble`
322 Wobble
323 //^^^^^^ Rename to `Wibble`
324 }
325 ```
326
327 Will now result in this code:
328
329 ```gleam
330 import wibble.{type Wibble, Wibble}
331
332 pub fn go() -> Wibble {
333 Wibble
334 }
335 ```
336
337 ([Andrey Kozhev](https://github.com/ankddev))
338
339- The language server now supports folding of comments and documentation
340 comments. For example, this code:
341
342 ```gleam
343 //// Very useful module.
344 ////
345 //// It could be used to make interesting things
346
347 /// Function to wibble.
348 ///
349 /// Not that it wobbles when wubble is true
350 pub fn wibble() {
351 // This todo here is temporary.
352 // It will need to be removed at some moment.
353 todo
354 }
355 ```
356
357 can now be folded to:
358
359 ```gleam
360 //// Very useful module. ...
361
362 /// Function to wibble. ...
363 pub fn wibble() {
364 // This todo here is temporary. ...
365 todo
366 }
367 ```
368
369 ([Andrey Kozhev](https://github.com/ankddev))
370
371- The "Convert to function call" code action will now convert the currently
372 hovered call and not only the final one.
373 ([Andrey Kozhev](https://github.com/ankddev))
374
375- When using the "Extract function" code action on statements whose values are
376 unused, the extracted function will return the last statement. For example:
377
378 ```gleam
379 fn main() {
380 //↓ start selection here
381 echo "line 2"
382 echo "line 3"
383 // ↑ end selection here
384 echo "line 4"
385 }
386 ```
387
388 will be turned into
389
390 ```gleam
391 fn main() {
392 function()
393 echo "line 4"
394 }
395
396 fn function() -> String {
397 echo "line 2"
398 echo "line 3"
399 }
400 ```
401
402 ([Gavin Morrow](https://github.com/gavinmorrow))
403
404- The language server now offers a code action to fix the new deprecated pipeline
405 syntax.
406 ([Surya Rose](https://github.com/GearsDatapacks))
407
408- The language server can now find references for and rename items when
409 triggered from an import statement:
410
411 ```gleam
412 import wibble.{type Wibble}
413 // ^^^^^^ Trigger find references or rename here
414
415 pub fn main() {
416 let _ = Wibble
417 }
418 ```
419
420 ([Gavin Morrow](https://github.com/gavinmorrow))
421
422- The language server now has "Convert to documentation comment" and
423 "Convert to regular comment" code actions. For example:
424
425 ```gleam
426 // Module description.
427 // Code action available here.
428
429 // Comment before function.
430 // Another code action here.
431 pub fn wibble() {
432 // No code action here.
433 todo
434 }
435
436 /// Doc comment.
437 /// Another code action here.
438 pub fn wobble () {
439 todo
440 }
441 ```
442
443 Triggering the code actions in all of these places will result in:
444
445 ```gleam
446 //// Module description.
447 //// Code action available here.
448
449 /// Comment before function.
450 /// Another code action here.
451 pub fn wibble() {
452 // No code action here.
453 todo
454 }
455
456 // Doc comment.
457 // Another code action here.
458 pub fn wobble () {
459 todo
460 }
461 ```
462
463 ([Daniel Venable](https://github.com/DanielVenable))
464
465- The "Generate Variant" code action now includes the name of the type to add
466 the variant to in its title.
467 ([0xda157](https://github.com/0xda157))
468
469### Formatter
470
471- Performance of the formatter has been improved.
472 `gleam format` has been measured to be up to 13% faster on projects like
473 `lustre`, with a 10% smaller peak memory footprint.
474 ([Giacomo Cavalieri](https://github.com/giacomocavalieri))
475
476- Formatter now removes import aliases if the aliased name is the
477 same as the original name. For example,
478
479 ```gleam
480 import wibble.{Wibble as Wibble}
481 ```
482
483 becomes
484
485 ```gleam
486 import wibble.{Wibble}
487 ```
488
489 ([Daniel Venable](https://github.com/DanielVenable))
490
491### Bug fixes
492
493- Fixed a bug where the generated Erlang `.app` file's `modules` list would only
494 contain the modules recompiled by the latest build, becoming empty on a warm
495 rebuild where nothing changed.
496 ([Charlie Tonneslan](https://github.com/c-tonneslan))
497
498- When using the language server to extract a function from within an anonymous
499 function, the return value of the extracted function is respected.
500
501 For example,
502
503 ```gleam
504 fn wibble() {
505 let wobble = fn() {
506 let random_number = 4
507 random_number * 42 // <- Extracting this line
508 }
509 }
510 ```
511
512 is turned into
513
514 ```gleam
515 fn wibble() {
516 let wobble = fn() {
517 let random_number = 4
518 function(random_number)
519 }
520 }
521 fn function(random_number: Int) -> Int {
522 random_number * 42
523 }
524 ```
525
526 ([Gavin Morrow](https://github.com/gavinmorrow))
527
528- Work around an ambiguity of the language server protocol that resulted in
529 editors like Zed inserting the wrong text when accepting type completions.
530 ([Giacomo Cavalieri](https://github.com/giacomocavalieri))
531
532- Fixed a bug where the post-publish message for pushing a git commit was
533 formatted incorrectly.
534 ([Louis Pilfold](https://github.com/lpil))
535
536- Fixed a bug where the compiler would generate invalid TypeScript type
537 definitions for records with a field named `constructor`.
538 ([Giacomo Cavalieri](https://github.com/giacomocavalieri))
539
540- Fixed a bug where the compiler would generate invalid code for `let assert`
541 expression with bit array patterns.
542 ([Giacomo Cavalieri](https://github.com/giacomocavalieri))
543
544- Fixed a bug where the compiler would evaluate the numerator and denominator
545 of a division in the wrong order.
546 ([Giacomo Cavalieri](https://github.com/giacomocavalieri))
547
548- Fixed a bug where the compiler would generate Erlang code that raises further
549 warnings for unused values.
550 ([Giacomo Cavalieri](https://github.com/giacomocavalieri))
551
552- Fixed a bug where the compiler would raise a warning for truncated int
553 segments when compiling a function with a JavaScript external.
554 ([Giacomo Cavalieri](https://github.com/giacomocavalieri))
555
556- Fixed a bug where the compiler would produce a confusing error message when
557 writing a constructor with a lowercase name.
558 ([Giacomo Cavalieri](https://github.com/giacomocavalieri))
559
560- Fixed a bug where guards with comments wouldn't be formatted properly.
561 ([Giacomo Cavalieri](https://github.com/giacomocavalieri))
562
563- A `gleam@@compile.erl` is no longer left in the build output of
564 `gleam compile-package`.
565 ([Louis Pilfold](https://github.com/lpil))
566
567- When using the language server to extract a function from within the body of a
568 use statement, only the selected statement(s) are extracted.
569
570 For example,
571
572 ```gleam
573 pub fn wibble() {
574 use wobble <- result.map(todo)
575 echo wobble as "1" // <- Extracting this line
576 echo wobble as "2"
577 }
578 ```
579
580 is turned into
581
582 ```gleam
583 pub fn wibble() {
584 use wobble <- result.map(todo)
585 function(wobble)
586 echo wobble as "2"
587 }
588 fn function(wobble: a) -> a {
589 echo wobble as "1"
590 }
591 ```
592
593 ([Gavin Morrow](https://github.com/gavinmorrow))
594
595- Fixed a bug where the JavaScript code generator could produce duplicate `let`
596 declarations when a variable was reassigned after being shadowed inside a
597 directly matching `case` branch.
598 ([Eyup Can Akman](https://github.com/eyupcanakman))
599
600- Fixed a bug where the language server would produce wrong code when triggering
601 rename of types and values with import aliases.
602 ([Andrey Kozhev](https://github.com/ankddev))
603
604- Fixed a bug where referencing qualified constructors in constant where a value
605 of the same name exists in scope would cause invalid code to be generated.
606 ([Surya Rose](https://github.com/GearsDatapacks))
607
608- Fixed a bug that would result in `gleam build` being slower than necessary
609 when finding the Gleam files of a package.
610 ([Giacomo Cavalieri](https://github.com/giacomocavalieri))
611
612- Fixed a bug where the compiler would not be able to correctly parse negative
613 numbers written in binary, octal, or hexadecimal base.
614 ([Giacomo Cavalieri](https://github.com/giacomocavalieri))
615
616- The formatter now properly formats binary operations in bit array size
617 segments.
618 ([Andrey Kozhev](https://github.com/ankddev))
619
620- Fixed a bug where after removing dependencies with `gleam remove` if a
621 removed dependency is still used the build would succeed, resulting in
622 runtime crash due to missing files.
623 ([Andrey Kozhev](https://github.com/ankddev))
624
625- The build tool will no longer panic when unable to lock the build directory.
626 ([Louis Pilfold](https://github.com/lpil))
627
628- The formatter now properly indents multiline trailing comments inside of
629 multiline lists and tuples.
630 ([0xda157](https://github.com/0xda157))
631
632- Fixed a bug where the compiler would panic on the first HTTPS request on
633 Android.
634 ([John Downey](https://github.com/jtdowney))
635
636- Fixed a bug where the language server would not show autocomplete for record
637 fields of internal types within the same package.
638 ([Surya Rose](https://github.com/GearsDatapacks))
639
640- Fixed a bug where warnings and errors in the arguments of a call to a
641 function literal would be reported multiple times.
642 ([John Downey](https://github.com/jtdowney))
643
644- Fixed a bug where pattern matching on overlapping string prefixes with guards
645 could generate incorrect JavaScript.
646 ([John Downey](https://github.com/jtdowney))
647
648- Fixed a bug where running `gleam docs build` on non-Erlang target projects
649 with a warm cache would not produce the module pages.
650 ([Matt Champagne](https://github.com/han-tyumi))
651
652- Fixed a bug where an incorrect `package-interface.json` would be generated for
653 certain type aliases.
654 ([Surya Rose](https://github.com/GearsDatapacks))
655
656- Fixed a bug where the compiler would report a module import as unused when
657 its local name matched another imported module's full name.
658 ([John Downey](https://github.com/jtdowney))