Release 10.0.0 · rescript-lang/rescript

Compiler

bsconfig.json does not support // line comments anymore.
- Example: "suffix": ".bs.js" // determine the suffix
- Fix: remove the comment and use standard json.
Changed return type of Js.String.match_ as it was wrong. #5070
- Example: any use of Js.String.match_ and Js.String2.match_
- Fix: follow the type errors

New records with optional fields e.g. type opt = {x: int, y?: string} were added as an experimental feature #5423 #5452 New Syntax
Add support for @new @variadic (see #5364)

Classify bigint correctly #5351
Fixed crash in rescript build on Windows #5516
Fixed rescript init command not working #5526
Fix issue with compiler log not terminated that causes problems with editor extension not clearing issues when fixed #5545

Changed Linux build to depend on GLIBC 2.28 again for compatibility with Debian 10.
Proper M1 support (CI now supports M1 native builds)

Syntax

@bs.send.pipe is now removed. Earlier it was deprecated.
Missing labels in function application is now an error (https://forum.rescript-lang.org/t/ann-more-strict-checks-in-missed-labels/2117).
- Example: let f = (x, ~z) => x + z; f(1, 2)
- Fix: do let f = (x, ~z) => x + z; f(1, ~z=2) instead
Externals without @val annotations do not work anymore, and externals with = "" give an error.
- Example: external setTimeout: (unit => unit, int) => float = "setTimeout" is not supported anymore.
- Fix: use @val external setTimeout: (unit => unit, int) => float = "setTimeout" instead.
- Example2: @val external setTimeout: (unit => unit, int) => float = "" is not supported anymore.
- Fix2: use @val external setTimeout: (unit => unit, int) => float = "setTimeout" instead.
Strings processed at compile-time don't need escaping anymore.
- Example: let blockCommentsRe = %re("/\\/\\*([^*]|[\\r\\n]|(\\*+([^*/]|[\\r\\n])))*\\*+\\//g").
- Fix: use let blockCommentsRe = %re("/\/\*([^*]|[\r\n]|(\*+([^*/]|[\r\n])))*\*+\//g") instead.
Remove parsing of "import" and "export" which was never officially supported rescript-lang/syntax#597 rescript-lang/syntax#599
- Example: export type t = int
- Fix: @genType type t = int
- Example2: import realValue: complexNumber => float from "./MyMath"
- Fix2: @genType.import("./MyMath") external realValue: complexNumber => float = "realValue"

Unicode is now supported in regular strings and chars (when the symbol fits). This is now going to work: let str = "Σ". And, you'll be able to pattern match on unicode chars: switch c { | 'Σ' => "what a fine unicode char" | _ => "unicode is fun" }
Doc comments /** ... */ are now supported. Inernally, they are attributes, so are only valid at positions where @foo is allowed, or a syntax error is given. Similarly for module-level /*** comments */ that can go where @@attributes go.

Libraries

"Attributes not allowed here". If you see this error chances are you're using a ppx that needs updating to a new version.
See an exampe of how to update a ppx
- Example: for rescript-relay 0.23.0 is not supported.
- Fix: use rescript-relay@beta or the new version when released.
Removed printing modules (Printf, Format etc) and related functions. Details of files added/removed: 0fd8bb0.

Several Belt / Js libraries are now converted to ReScript syntax, with corresponding comments in Markdown format suitable for hovering. See #5361.

Playground

Added jsoo_playground_main.ml as the rescript-lang.org playground bundle entrypoint

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