Introduce function count() for arrays & strings

[sshymko]

Usage example with dynamic jobs:

name: Dynamic jobs
on:
  workflow_dispatch:
    inputs:
      versions:   
jobs:
  deploy:
    name: Deploy ${{ count(fromJson(github.event.inputs.versions)) }} versions
    runs-on: ubuntu-latest
    strategy:
      matrix:
        version: ${{ fromJson(github.event.inputs.versions) }}
    name: Deploy version ${{ matrix.version }}
    steps:
      - run: echo "hello world"

Sample input:

{
  "versions": "[\"1\",\"2\",\"3\"]"
}

[sshymko]

I'd prefer à la JavaScript property syntax array.length over the count() function, but have no idea how to implement that.

Desirable syntax:

${{ fromJson(github.event.inputs.versions).length }}
${{ (fromJson(steps.example.outputs.json).items.*).length }}

Note that the filtering items.* converts object properties (hash map) to an array.

[sshymko]

See related #865 introducing split() function to parse arrays from strings instead of JSON.

[AllanOricil]

Why haven't this been merged?