nandi.uk
Fork of daniellemaywood.uk/gleam — Wasm codegen work
1<!--
2 SPDX-License-Identifier: Apache-2.0
3 SPDX-FileCopyrightText: 2020 The Gleam contributors
4-->
5
6# Changelog
7
8## v1.16.0 - 2026-04-24
9
10## v1.16.0-rc4 - 2026-04-22
11
12### Build tool
13
14- Enabling JavaScript source map generation will now copy the source Gleam
15 files to the output directory. This means that source maps will work in
16 browsers without any further processing before being served.
17 ([Louis Pilfold](https://github.com/lpil))
18
19### Bug fixes
20
21- The `sources` property of source map files now uses a relative URL to the
22 source file. Previously it was using a filesystem path, which would not work
23 in all JavaScript environments.
24 ([Louis Pilfold](https://github.com/lpil))
25
26## v1.16.0-rc3 - 2026-04-20
27
28### Build tool
29
30- New Gleam packages are now generated requiring `>= 1.0.0` of `gleam_stdlib`.
31 ([Surya Rose](https://github.com/GearsDatapacks))
32
33### Bug fixes
34
35- Fixed a bug where certain invalid programs would type check if they contained
36 many mutually recursive functions.
37 ([Surya Rose](https://github.com/GearsDatapacks))
38
39## v1.16.0-rc2 - 2026-04-14
40
41### Build tool
42
43- Added `mts`, `cts`, `jsx`, `tsx` to native file extensions so you can use
44 external JavaScript code from files with these file extensions.
45 ([Niklas Kirschall](https://github.com/nkxxll))
46
47### Bug fixes
48
49- `manifest.toml` files with invalid package names now raise an error
50 immediately when the file is parsed.
51 ([Louis Pilfold](https://github.com/lpil))
52
53- Fixed a bug where the "Wrap in anonymous function" code action could be used
54 in the body of a `use` expression
55 ([Giovanni Maria Zanchetta](https://github.com/GioMaz))
56
57## v1.16.0-rc1 - 2026-04-10
58
59### Compiler
60
61- The compiler now reports all errors and warnings it can find in modules that
62 do not depend on each other, while previously it would always stop at the
63 first module with an error.
64 ([Giacomo Cavalieri](https://github.com/giacomocavalieri))
65
66- The compiler now supports list prepending in constants. For example:
67
68 ```gleam
69 pub const viviparous_mammals = ["dog", "cat", "human"]
70
71 pub const all_mammals = ["platypus", "echidna", ..viviparous_mammals]
72 ```
73
74 ([Surya Rose](https://github.com/GearsDatapacks))
75
76- The analysis of record update expressions is now fault tolerant, meaning the
77 compiler will no longer stop reporting errors at the first invalid field it
78 finds.
79 ([Giacomo Cavalieri](https://github.com/giacomocavalieri))
80
81- The compiler now shows a better error message when trying to use the record
82 update syntax with variants that have no labelled fields.
83 ([Giacomo Cavalieri](https://github.com/giacomocavalieri))
84
85- The error message for invalid deprecated attributes with no deprecation
86 message has been improved. For example, the following code:
87
88 ```gleam
89 pub type HashAlgorithm {
90 @deprecated
91 Md5
92 Sha224
93 Sha512
94 }
95 ```
96
97 Will raise the following error:
98
99 ```txt
100 error: Syntax error
101 ┌─ /src/parse/error.gleam:3:3
102 │
103 3 │ @deprecated
104 │ ^^^^^^^^^^^ A deprecation attribute must have a string message.
105
106 See: https://tour.gleam.run/functions/deprecations/
107 ```
108
109 ([Giacomo Cavalieri](https://github.com/giacomocavalieri))
110
111- The compiler now raises a warning on the JavaScript target when defining an
112 int segment with a size higher than 52 bits. For example, this code:
113
114 ```gleam
115 pub fn go(sha: BitArray) {
116 let <<_, number:152>> = sha
117 number
118 }
119 ```
120
121 Will result in the following warning:
122
123 ```txt
124 warning: Truncated bit array segment
125 ┌─ /src/app/warning.gleam:3:20
126 │
127 3 │ let <<_, number:152>> = sha
128 │ ^^^
129
130 This segment is a 152-bit long int, but on the JavaScript target
131 numbers have at most 52 bits. It would be truncated to its first 52 bits.
132 Hint: Did you mean to use the `bytes` segment option?
133 ```
134
135 ([Giacomo Cavalieri](https://github.com/giacomocavalieri))
136
137- The compiler now emits a helpful error message when source code contains an
138 invalid unicode character that looks similar to a correct character.
139
140 ```
141 error: Syntax error
142 ┌─ /src/parse/error.gleam:1:20
143 │
144 1 │ pub fn main() { #(1‚ 2) }
145 │ ^ Unexpected character
146
147 This looks like ascii comma, but it is actually the unicode low single
148 comma quotation mark.
149 ```
150
151 ([Louis Pilfold](https://github.com/lpil))
152
153- The compiler now emits more efficient code when matching on single-character
154 string prefixes on the JavaScript target. For example, the `glance` package
155 is now nearly 30% faster on the JavaScript target:
156
157 ```
158 # before:
159 min: 10.8ms, max: 365.82ms, median: 14.74ms, mean: 14.76ms
160 warmup: 100/1.5s, total post-warmup: 1000/14.76s
161
162 # after:
163 min: 8.96ms, max: 143.76ms, median: 10.72ms, mean: 11.06ms
164 warmup: 100/1.24s, total post-warmup: 1000/11.06s
165 ```
166
167 ([Surya Rose](https://github.com/GearsDatapacks))
168
169- The compiler can now emit source maps when targeting JavaScript. This can be
170 enabled in the `gleam.toml` with the `source_maps` setting under the
171 `javascript` section.
172 ([Ameen Radwan](https://github.com/Acepie))
173
174### Build tool
175
176- The `gleam hex owner add` command has been added, which allows adding
177 owners to the package.
178 ([Niklas Kirschall](https://github.com/nkxxll))
179
180- When publishing, the package manager now uses the full term instead of the
181 shorthand "MFA" in the prompt and error message.
182 ([Luka Ivanović](https://github.com/luka-hash))
183
184- When Hex rejects publish with error 422, show error message instead of
185 defaulting to "can only modify a release up to one hour after publication"
186 ([David Matz](https://github.com/d-matz))
187
188- The `gleam publish` command now has documentation for its options.
189 ([Giacomo Cavalieri](https://github.com/giacomocavalieri))
190
191- The `gleam hex retire` command now accepts three flags `--package`,
192 `--version`, and `--reason` instead of positional arguments.
193 ([Giacomo Cavalieri](https://github.com/giacomocavalieri))
194
195- The `gleam hex unretire` command now accepts two flags `--package`, and
196 `--version` instead of positional arguments.
197 ([Giacomo Cavalieri](https://github.com/giacomocavalieri))
198
199- The `gleam hex owner transfer` command now accepts a flag `--package` instead
200 of a positional argument.
201 ([Giacomo Cavalieri](https://github.com/giacomocavalieri))
202
203- The `gleam docs build` command no longer recompiles all the project's
204 dependencies every single time it is run.
205 ([Giacomo Cavalieri](https://github.com/giacomocavalieri))
206
207- The build tool now produces a nicer error message when trying to add a
208 package's version that doesn't exist. For example, running `gleam add wisp@11`
209 will now produce:
210
211 ```txt
212 error: Dependency resolution failed
213
214 The package `wisp` has no versions in the range >= 11.0.0 and < 12.0.0.
215 ```
216
217 ([Giacomo Cavalieri](https://github.com/giacomocavalieri))
218
219- The build tool will now suggest to create a module in the `dev` or `test`
220 directory, if that missing module is a dev module or a test module
221 respectively.
222 ([Andrey Kozhev](https://github.com/ankddev))
223
224- Now all options with declared variants have consistent representation of
225 possible values.
226 ([Andrey Kozhev](https://github.com/ankddev))
227
228- New Gleam packages are generated requiring >= 0.70.0 of `gleam_stdlib`.
229 ([Louis Pilfold](https://github.com/lpil))
230
231- `gleam.toml` files with invalid dependency names now raise an error
232 immediately when the file is parsed.
233 ([Louis Pilfold](https://github.com/lpil))
234
235- Documentation for `--target` option has been improved to include more
236 details.
237 ([Andrey Kozhev](https://github.com/ankddev))
238
239### Language server
240
241- The language server will now show a diagnostic if you have a file open that
242 could not be analysed due to its dependencies failing to compile.
243 ([Giacomo Cavalieri](https://github.com/giacomocavalieri))
244
245- The language server now offers code actions to wrap a function reference in an
246 anonymous function, or to remove a trivial anonymous function, leaving its
247 contents. For example:
248
249 ```gleam
250 pub fn main() {
251 [-1, -2, -3] |> list.map(fn(a) { int.absolute_value(a) })
252 // ^^ Activating the "Remove anonymous function"
253 // code action here
254 }
255 ```
256
257 Would result in:
258
259 ```gleam
260 pub fn main() {
261 [-1, -2, -3] |> list.map(int.absolute_value)
262 }
263 ```
264
265 While the other action would reverse the change.
266
267 ([Eli Treuherz](http://github.com/treuherz))
268
269- The "extract function" code action can now be used in pipelines to extract a
270 part of one into a function. For example, triggering it here:
271
272 ```gleam
273 pub fn words() {
274 string
275 |> string.lowercase
276 // ^^^
277 |> string.replace(each: "jak", with: "lucy")
278 // ^^^ selecting these two steps of the pipeline
279 |> string.split(on: " ")
280 }
281 ```
282
283 Would result in the following code:
284
285 ```gleam
286 pub fn words() {
287 string
288 |> function
289 |> string.split(on: " ")
290 }
291
292 fn function(string: String) -> String {
293 string
294 |> string.lowercase
295 |> string.replace(each: "jak", with: "lucy")
296 }
297 ```
298
299 ([Giacomo Cavalieri](https://github.com/giacomocavalieri))
300
301- The "extract function" code action can now be used to extract the right hand
302 side of an assignment into its own function. For example, triggering it here:
303
304 ```gleam
305 pub fn personal_blog() {
306 let introduction =
307 html.main([], [
308 html.h1([], [html.text("Hello, world!")]),
309 html.p([], [html.text("Gleam is cool")])
310 ])
311 //^^^ Triggering "extract function" on this expression
312
313 html.body([introduction, blog_posts()])
314 }
315 ```
316
317 Would result in the following code:
318
319 ```gleam
320 pub fn personal_blog() {
321 let introduction = function()
322 html.body([introduction, blog_posts()])
323 }
324
325 pub fn function() {
326 html.main([], [
327 html.h1([], [html.text("Hello, world!")]),
328 html.p([], [html.text("Gleam is cool")])
329 ])
330 }
331 ```
332
333 ([Giacomo Cavalieri](https://github.com/giacomocavalieri))
334
335- The "extract variable" code action can now pick better names for variables in
336 case branches and blocks, ignoring unrelated names of variables in other
337 branches.
338 ([Giacomo Cavalieri](https://github.com/giacomocavalieri))
339
340- The language server now has a code action to replace a `_` in a type
341 annotation with the corresponding type. For example:
342
343 ```gleam
344 pub fn load_user(id: Int) -> Result(_, Error) {
345 // ^
346 // Triggering the code action here
347 sql.find_by_id(id)
348 |> result.map_error(CannotLoadUser)
349 }
350 ```
351
352 Triggering the code action over the `_` will result in the following code:
353
354 ```gleam
355 pub fn load_user(id: Int) -> Result(User, Error) {
356 sql.find_by_id(id)
357 |> result.map_error(CannotLoadUser)
358 }
359 ```
360
361 ([Giacomo Cavalieri](https://github.com/giacomocavalieri))
362
363- The language server now shows completions for the labelled argument of a
364 record when writing a record update.
365 ([Giacomo Cavalieri](https://github.com/giacomocavalieri))
366
367- The language server no longer shows completions for values when editing a
368 qualified type.
369 ([Giacomo Cavalieri](https://github.com/giacomocavalieri))
370
371### Formatter
372
373- The formatter no longer moves comments out of type annotations.
374 ([Giacomo Cavalieri](https://github.com/giacomocavalieri))
375
376- The formatting of long nested tuples has been improved.
377 Previously the formatter would split only the last tuple:
378
379 ```gleam
380 #(#(wibble, wobble), #(some_long_tuple, passed_as_last_argument))
381 // after format:
382 #(#(wibble, wobble), #(
383 some_long_tuple,
384 passed_as_last_argument
385 ))
386 ```
387
388 But now it favours first splitting each element onto its own line:
389
390 ```gleam
391 #(#(wibble, wobble), #(some_long_tuple, passed_as_last_argument))
392 // after format:
393 #(
394 #(wibble, wobble),
395 #(some_long_tuple, passed_as_last_argument)
396 )
397 ```
398
399 ([Giacomo Cavalieri](https://github.com/giacomocavalieri))
400
401### Bug fixes
402
403- Fixed a bug where some functions could be formatted to be longer than 80
404 characters.
405 ([Giacomo Cavalieri](https://github.com/giacomocavalieri))
406
407- Fixed a bug that would result in not being able to publish a package if some
408 non-ASCII characters were used in field names other than `description`.
409 ([Niklas Kirschall](https://github.com/nkxxll))
410
411- Fixed a bug where arithmetic operators in bit array size expressions were
412 not left-associative, causing `a - b - c` to be evaluated as
413 `a - (b - c)` instead of `(a - b) - c`.
414 ([Daniele Scaratti](https://github.com/lupodevelop))
415
416- Fixed a bug where the compiler would crash when trying to read the cache for
417 modules containing large constants.
418 ([Surya Rose](https://github.com/GearsDatapacks))
419
420- Fixed a bug where `BitArray$BitArray$data` constructed a `DataView` with
421 incorrect byte length instead of the slice's actual size, causing sliced bit
422 arrays to include extra bytes from the underlying buffer on JavaScript.
423 ([John Downey](https://github.com/jtdowney))
424
425- The compiler now parses UTF-8 source files with a byte-order mark correctly,
426 instead of raising an error.
427 ([Lucy McPhail](https://github.com/lucymcphail))
428
429- Fixed a bug where semicolons would not be properly added to pipelines in
430 generated JavaScript code, leading to runtime errors in certain circumstances.
431 ([Surya Rose](https://github.com/GearsDatapacks))
432
433- Fixed a bug where the compiler would not generate the correct code on the
434 Erlang target for bit array string segments with the `utf16` and `utf32`
435 option.
436 ([Giacomo Cavalieri](https://github.com/giacomocavalieri))
437
438- Fixed the formatting of some errors' hints to properly wrap.
439 ([Giacomo Cavalieri](https://github.com/giacomocavalieri))
440
441- Fixed a bug where box drawing characters would not use the same monospace font
442 as all other characters inside code blocks in the generated documentation.
443 ([Giacomo Cavalieri](https://github.com/giacomocavalieri))
444
445- Fixed a bug where the "Add missing type parameter" code action could be
446 triggered on types that do not exist instead of type variables.
447 ([Giacomo Cavalieri](https://github.com/giacomocavalieri))
448
449- Fixed a bug where the "Add missing patterns" code action could end up deleting
450 comments inside an incomplete case expression.
451 ([Giacomo Cavalieri](https://github.com/giacomocavalieri))
452
453- Fixed a bug where the "Extract function" could generate invalid code when
454 triggered on a use statement inside a block.
455 ([Giacomo Cavalieri](https://github.com/giacomocavalieri))
456
457- Fixed a bug where constants referenced in a bit-array pattern's size option
458 would report as unused.
459 ([Louis Pilfold](https://github.com/lpil))
460
461- Fixed a bug where the JavaScript code generator could produce duplicate `let`
462 declarations for internal variables after a `case` expression whose subject
463 directly matches one of the branches.
464 ([Eyup Can Akman](https://github.com/eyupcanakman))
465
466## v1.15.1 - 2026-03-17
467
468### Bug fixes
469
470- Fixed a bug where `BitArray$BitArray$data` constructed a `DataView` with
471 offset 0 instead of the slice's actual byte offset, causing sliced bit arrays
472 to read from the wrong position in the underlying buffer on JavaScript.
473 ([John Downey](https://github.com/jtdowney))