thread first (->)
threads value through calls as their first argument
(-> expr forms*)
Evaluates expr and threads it through the supplied forms as their first argument. Any form that is not already a function call will be converted into one before threading.
(-> 0 (+ 10) (* 2) (/ 5))
Will expand to
(/ (* (+ 0 10) 2) 5) and return 4.