macro
boot.janet on line 502, column 1
(forv i start stop & body)
Do a C-style for-loop for side effects. The iteration variable `i`
can be mutated in the loop, unlike normal `for`. Returns nil.
(forv i 0 10
(print "hello"))
# => hello
# => hello
# => hello
# => hello
# => hello
# => hello
# => hello
# => hello
# => hello
# => hello
# => nil
(do
(def coll @[])
(forv i 0 9
(array/push coll i)
(+= i 2))
coll)
# => @[0 3 6]