Array types are incompatible

[Laruxo]

Is your feature request related to a problem? Please describe.

I am a bit frustrated with the use of this pattern:

State extends "empty" ? [] : [RTNode, ...RTNode[]]

In my code, I have custom types holding data like nodes: RTNode[] or slices: Slice[]. However, these types are not compatible with [] | [RTNode, ...RTNode[]].

I would love to hear more context about this pattern and why did you decide to use it instead of never[] | RTNode[].

Describe the solution you'd like

Ideally, Typescript would understand that [] | [RTNode, ...RTNode[]] is equivalent to RTNode[] (both ways). Until then I would prefer simpler types without this State (e.g. never[] | RTNode[])

[github-actions[bot]]

This issue has been labeled as a feature request since it was created using the 🙋‍♀️ Feature Request Template.

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[angeloashmore]

Hi @Laruxo, I'm sorry for the late reply.

State extends "empty" ? [] : [RTNode, ...RTNode[]] was preferred over RTNode[] because it more explicitly defines what happens when a field is empty or filled.

The State type parameter allows the types to be smart enough to tell you when you are passing a field value into something that expects a filled value. @prismicio/client's isFilled helpers (e.g. isFilled.image(imageField)), lets you narrow the type to a filled or empty value. That narrowing could help write stronger code that is type checked. If you don't use the isFilled helpers, should still be able to conditionally access properties by performing other runtime checks.

We recommend that you use the field-level types from @prismicio/client rather than the lower-level types like RTNode and Slice[]. For example, you can use RichTextField and SliceZone instead.

I'll leave this topic open for now in case you or anyone else would like to share other viewpoints. What I explained above details our original design, but that doesn't mean we can't change it. 🙂

[lihbr]

Closing as stale, happy to reopen if anyone wants to continue the discussion~

Thanks for contributing!