/// Self-reference binding available inside every lambda/macro call body.
pub const THIS_CALLABLE: &str = "this";

/// Binding containing all arguments passed to the current callable.
pub const ALL_ARGS: &str = "%%";

/// Binding containing arguments beyond the declared named parameters.
pub const REST_ARGS: &str = "%&";

/// Runtime variable holding the resolved directory of the currently executing file.
pub const DIR: &str = "__dir__";

/// Special symbol that evaluates to the current scope as a map value.
pub const SCOPE: &str = "__scope__";

/// Map key inserted into every scope-map to identify it as a scope object.
pub const IS_SCOPE: &str = "__is_scope__";

/// Map key that makes a map value callable (callable-object protocol).
pub const CALL: &str = "__call__";

/// Keyword representing the null / absent value.
pub const KW_NULL: &str = "null";