Piping data through arbitrary functions in Clojure

Question

I know that the -> form can be used to pass the results of one function result to another:

(f1 (f2 (f3 x))) 
(-> x f3 f2 f1) ; equivalent          


        

Answer 1

If functions is a sequence of functions, you can reduce it using comp to get a composed function. At a REPL:

user> (def functions (list #(* % 5) #(+ % 1) #(/ % 3)))
#'user/my-list
user> ((reduce comp functions) 9)
20

apply also works in this case because comp takes a variable number of arguments:

user> (def functions (list #(* % 5) #(+ % 1) #(/ % 3)))
#'user/my-list
user> ((apply comp functions) 9)
20