How to chain multiple functions?

Question

I'm trying to chain a few functions in Clojure:

(f4 (f3 (f2 (f1 foo))))

Is there any convenient syntax sugar for this? Something like:

(with-all-of-them foo f1 f2 f3 f4)

see http://stackoverflow.com/questions/11918554/can-clojure-evaluate-a-chain-of-mixed-arity-functions-and-return-a-partial-funct and see if that helps you — , May 27 '13 at 12:26

score 9 · Accepted Answer · answered May 27 '13 at 12:29

9

Use -> macro.

(-> foo f1 f2 f3 f4)

Or reduce:

(reduce #(%2 %1) foo [f1 f2 f3 f4])

answered May 27 '13 at 12:29

Ankur

3

@vemv I think the `->` is cute. The `reduce` option clearly shows the operational pattern, and, unlike the threading macro, is happy to take on a sequence unknown at compile-time. – A. Webb May 27 '13 at 13:47

score 5 · Answer 2 · answered May 27 '13 at 12:28

5

(-> foo f1 f2 f3 f4)

answered May 27 '13 at 12:28

Alex B

Next to Figwheel this is seriously the most awesome thing I have seen today. – user2609980 Apr 14 '16 at 22:01

Michiel Borkent · Answer 3 · 2013-05-27T15:05:02.700

4

Actually your description of with-all-of-them is very close to comp, except that comp returns a function that you must call yourself:

(f4 (f3 (f2 (f1 foo)))) == ((comp f4 f3 f2 f1) foo)

So, with-all-of-them could be implemented as follows:

(defn with-all-of-them [arg & fs]
   ((apply comp fs) arg))

edited May 27 '13 at 15:05

answered May 27 '13 at 14:37

Michiel Borkent

3 Answers3