Question

In Clojure, what is the best way for iterating concurrently on two seqs and calling a function on the two running elements?
For example:

(def a (range 3))
(def b (range 100 103))
(defn my-func [] ...) ;some custom code

The code should execute my-func 3 times, like this:

(my-func 0 100)
(my-func 1 101)
(my-func 2 102)

How can I achieve that without defining any function or macro?

Answer 1

map is exactly what you need, it takes a function and any number of seqs and calls them just as you wish.

(def a (range 3))
(def b (range 100 103))
user=> a
(0 1 2)
user=> b
(100 101 102)

user=> (defn my-func [a b] (str a ":" b))
#'user/my-func

user=> (my-func 1 2)
"1:2"

user=> (map my-func a b)
("0:100" "1:101" "2:102")

and because map is lazy if you want the function to actually run now:

(doall (map my-func a b))