`$select` Support

[RDIL]

Add support for that wacky node that Govert found.

[AnthonyFuller]

What does it actually do?

[grappigegovert]

The $select action runs an action for every element in an array that matches a condition
Syntax is like this

"$select": {
  "in": [1, 2, 3],
  "?": {
    "$gt": ["$.#", 1]
  },
  "!": [
    "$inc": ["$.myvariable", "$.#"]
  ]

This would add the values 2 and 3 to the context var myvariable

There are no official contracts or challenges that use it, and afaik the functionality was added in H3.

[AnthonyFuller]

That's actually really nice, I like that.

[AnthonyFuller]

Question: what happens if you just put a number for in, does it just not do anything?

[grappigegovert]

I'm not entirely sure, but I think it'll crash during loading.
You can do "in": "$.contextVar", just like you can with $all, $any, and $inarray, to use a context var as input array and I think that will do nothing if contextVar is not an array.
I don't have all the behaviour written down yet, so this might be incorrect.