Allow keyword arguments to appear anywhere in a call

Feature Spec

Keyword arguments are not positional by definition, and there could be stylistic reasons to want to put them before positional arguments.

Consider (beautiful):

new cloud.Function(timeout: 1m, inflight () => {
  log("my function!");
});

Versus (ugly):

new cloud.Function(inflight () => {
  log("my function!");
}, timeout: 1m);

To complement this behavior, I am proposing that we also add a special syntax (I propose to use a spread ...) to denote that a struct needs to be expanded into keyword arguments:

let fn = (pos1: str, pos2: num, opts: ...MyOptions) => { ... }

If the spread is not specified, opts will not expand into keywords.

For practical reasons, When importing JSII functions, we will still automatically assume that the last struct argument is expanded.

Use Cases

Ergonomics and style improvements.

Implementation Notes

No response

Component

Compiler

Community Notes

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winglang / wing