Wolfram: Atomic Expression

By Xah Lee. Date: . Last updated: .

An atom is a indivisible Expression .

An atom is one of:

AtomQ[expr]

return True if expression is a atom, else False.

AtomQ

(* all True *)
AtomQ[ 3 ]
AtomQ[ 3.1 ]
AtomQ[ 3/4 ]
AtomQ[ Pi ]
AtomQ[ I ]
AtomQ[ 3 + I ]
AtomQ[ x ]
AtomQ[ "some" ]
AtomQ[ List ]
AtomQ[ List[] ]
(* False *)

AtomQ[ {} ]
(* False *)

AtomQ[ f[] ]
(* False *)

AtomQ[ x + y ]
(* False *)

Expression, Atom, Head