option to transform RunicArgs

[harrysolovay]

Let's say that we have the following Rune factory:

function greeting<X>(...args: RunicArgs<X, [name: string, isCool: boolean]>) {
  const [name, isCool] = RunicArgs.resolve(args)
  // ... do something with these Runes
}

What do we do if we want to transform one of the supplied Runes?

function greeting<X>(...args: RunicArgs<X, [name: string, isCool: boolean]>) {
  const name = Rune.resolve(args[0]).map(upperCaseFirst)
  const isCool = Rune.resolve(args[1])
  // ...
}

^ this isn't super clean. One place where this is especially apparent is in the instantiate method of InkMetadataRune, in which we want to fallback to sensible defaults for certain arguments when not provided.

Solution

I propose that RunicArgs.resolve accept an optional second argument, a partial mapping from index to transform.

function greeting<X>(...args: RunicArgs<X, [name: string, isCool: boolean]>) {
  const [name, isCool] = RunicArgs.resolve(args, { 0: upperCaseFirst })
  //
}

In the case of the aforementioned instantiate method:

instantiate<X>(props: RunicArgs<X, InstantiateProps>) {
- const salt = Rune
-   .resolve(props.salt)
-   .unhandle(undefined)
-   .rehandle(undefined, this.salt)
- const value = Rune
-   .resolve(props.value)
-   .unhandle(undefined)
-   .rehandle(undefined, () => Rune.constant(0n))
+ const { salt, value, ... } = RunicArgs.resolve(props, {
+   salt: (v) => v ?? this.salt(),
+   value: (v) => v ?? 0n,
+ })

  // ...