set-first
builtin-function
(set-first seq item)
Sets the first element of seq to item.
seq
item
make-html > (let seq '(a 2 3 4)) it: seq make-html > (set-first seq 'a) it: a make-html > (macroexpand '(setf (first seq) 'a)) it: (set-first seq 'a)