Special data types

Type Description
Callable A callable value that can be executed by transmitting arguments in parentheses in YQL's SQL syntax or with the Apply function when s-expressions syntax is used.
Resource Resource is an opaque pointer to a resource you can pass between the user defined functions (UDF). The type of the returned and accepted resource is declared inside a function using a string label. When passing a resource, YQL checks for label matching to prevent passing of resources between incompatible functions. If the labels mismatch, a type error occurs.
Tagged Tagged is the option to assign an application name to any other type.
Generic The data type used for data types.
Unit A data type for non-computable entities (data sources and recipients, atoms, etc.).
Null Void is a singular data type with the only possible null value. It's the type of the NULL literal and can be converted to any Optional type.
Void Void is a singular data type with the only possible null value.
EmptyList A singular data type with the only possible [] value. It's the type of the [] literal and can be converted to any List type.
EmptyDict A singular data type with the only possible {} value. It's a type of the {} literal and can be converted to any Dict or Set type.