Rx: Simple, Extensible Schemata

//nil

//nil accepts only an undefined or valueless datum. This is distinct from the lack of any data, however. For example:

This array contains one entry, which //nil accepts:

[ null ]

This array contains no entries, so there's nothing for //nil to consider.

[ ]

The //nil type takes no parameters.

/.meta/nil, the schema for //nil definitions:

{
  "type": "//rec",
  "required": {
    "type": { "type": "//str", "value": "//nil" }
  }
}