Azure Policy to apply naming conventions

azure-resource-naming-policy.json

{
  "mode": "Indexed",
  "policyRule": {
    "if": {
      "allOf": [
        {
          "field": "type",
          "notequals": "Microsoft.Resources/subscriptions/resourceGroups"
        },
        {
          "anyOf": [
            {
              "count": {
                "value": [
                  "ai",
                  "kv",
                  "sql",
                  "app",
                  "search"
                ],
                "name": "pattern",
                "where": {
                  "anyOf": [
                    {
                      "value": "[split(field('name'), '-')[0]]",
                      "like": "[current('pattern')]"
                    },
                    {
                      "value": "[count(split(field('name'), '-'))]",
                      "equals": 1
                    }
                  ]
                }
              },
              "notEquals": 1
            },
            {
              "count": {
                "value": [
                  "dev",
                  "prod"
                ],
                "name": "pattern",
                "where": {
                  "anyOf": [
                    {
                      "value": "[last(split(field('name'), '-'))]",
                      "like": "[current('pattern')]"
                    },
                    {
                      "value": "[count(split(field('name'), '-'))]",
                      "equals": 1
                    }
                  ]
                }
              },
              "notEquals": 1
            }
          ]
        }
      ],
      "then": {
        "effect": "deny"
      }
    },
    "parameters": {}
  }
}

Could you proved an update on this, please? When trying to use it I receive the following error "The inner exception 'The function 'count' defined in policy is invalid."

I could see this having great potential.