boolean (Type)

Supertypes:

boolean, symbol, t

Description:

The type boolean contains the symbols t and nil, which represent true and false, respectively.

See Also:

t (Constant Variable), nil (Constant Variable), if, not (Function), complement

Notes:

Conditional operations, such as if, permit the use of generalized booleans, not just booleans; any non-nil value, not just t, counts as true for a generalized boolean. However, as a matter of convention, the symbol t is considered the canonical value to use even for a generalized boolean when no better choice presents itself.