Proposal: add types :list and :non_empty_list

[leandrocp]

Proposal: add types :list and :non_empty_list

[josevalim]

We would probably need them to be {:list, ...} and {:non_empty_list, ...}. But I would collect more feedback first, so I would recommend rolling with a custom option for now.

[whatyouhide]

@leandrocp yes of course! Feel free to reach out if you need any help 👍

[whatyouhide]

I'm on the fence on this one because "complex types" are risky: we'd have to maybe support :map, :enum, and friends and it might set a dangerous precedent. On the other hand, nimble_options is pragmatic and in my experience with it, I needed to validate lists a lot already. So, I'd probably go for it.

My API suggestion:

{:list, type, options}

where:

• type - any nimble_options type, such as :string, {:custom, mod, fun, args}, and so on
• options:
  • :min_length
  • :max_length
  • :length

This would avoid having :non_empty_list and at the same time be much more flexible. Thoughts?

[josevalim]

I would go easy: start with {:list, type} and expand if necessary.

[leandrocp]

{:list, type} sounds good to me. May I work on a PR?