boolean (original) (raw)

ANSI Common Lisp 4 Types and Classes 4.4 Dictionary of Types and Classes

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,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.

Allegro CL Implementation Details:

None.