nil

[constant] nil

Boolean false, an empty list, and a symbol 'nil, like Common Lisp.

[constant] t

Boolean true and a symbol 't, like Common Lisp.

Notes in arc0:

• (type nil) and (type t) returns sym.
• You can't rebind global nil and t, but arc0 doesn't complain if you bind them locally. (t can be bound as local variable; nil is always nil).