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Special Forms > Looping: loop and recur
Looping: loop and recur
Clojure provides a number of useful imperative looping
constructs, including doseq and
dotimes, all of which are built upon
recur. recur transfers control to the local-most
loop head without consuming stack space, which is
defined either by loop or a function.
Let’s take a look at a very simple countdown loop:
(loop [x 5](if (neg? x) x
(recur (dec x))))
;= -1
-
loopestablishes bindings via an implicitletform, so it takes a vector of binding names and initial values. -
If the final expression within a
loopform consists of a value, that is taken as the value of the form itself. Here, whenxis negative, theloopform returns the value ofx.
