Revisit JSX syntax

[nojaf]

Proposal: Bring ReScript JSX Closer to the JavaScript JSX Spec

Currently, ReScript JSX differs from JavaScript’s JSX in a few key ways (docs).
I propose moving ReScript JSX closer to the official JSX spec in a future release.

Example

// Current
let foo = <p>{React.string("Hello")}</p>

// Proposed
let foo = <p>Hello</p>

Right now, Hello is treated as a React.element rather than as JSXText.
This means plain text inside JSX must be wrapped in React.string(...), unlike in JavaScript JSX.

Suggested Path Forward

Step 1: Formatter update

The formatter could automatically insert braces for identifiers used as children, making the output more consistent.

// Original
let foo = <p>children</p>

// After format 
// (notice how there's no space before the opening curly brace and after the closing one)
let foo = <p>{children}</p>

Step 2: Parser update

Next, the parser could be extended to handle JSXText as valid child input—bringing ReScript JSX semantics in line with the JSX spec.

Note

This change will only affect syntax and won't change the type of JSX children.
Inside curly braces you'll still need React.string:

<div>
 {switch count {
 | 1 => "once"
 | n => `Int.toString(n) times`
 }->React.string}
</div>

This could also affect custom components where children are not typed as JSX element and that are often used with literals, eg before:

<Counter>6</Counter>

after:

<Counter>{6}</Counter>

This is still an early-stage idea, so feedback is welcome. Don't hesitate to chime in if you think your codebase would be affected by this change.
Please use 👍 / 👎 / 👀 to indicate your opinion.
This is just a signal, not a binding vote.

[fhammerschmidt]

As long as we don't get rid of argument punning I am all for it.

[nojaf]

you'll still need React.string:

Would be interesting to explore is we can avoid that restriction as well.
If we can automatically coerce during type-checking that be neat as well.
Not sure how challenging this would be.