[Avshalom]

on the other hand = is one character, and if it's not a legal character in identifiers then x=1 y=2 z=3 takes 2n characters (setf x 1 y 2 z 3) takes 2n+7 characters (plus however many we're using for the actual identifies and values but those'll be the same between examples)

[kazinator]

Lisp has an = function; so that binding is taken. Symbols in the keyword package are allowed to have function bindings, and so a synonym for setf can be called := (the symbol named "=" in the keyword package).

  [1]> (defmacro := (&rest args) `(setf ,@args))
  :=
  [2]> (defvar a)
  A
  [3]> (:= a 42)
  42
  [4]> a
  42
  [5]> (= a 42)
  T