How to implement a For loop in Clojure

Question

I'd like to implement this little code in Clojure, but I am struggling:

struct mystruct {    int id;    int price; };  mystruct mydata[10];  for (int i=0; i<10; i++) {   myfunction(mydata[i].id, mydata[i].price);   //other things... } 

I am a beginner with Clojure and it's really complicated for me to do something simple like this, but I am really trying to learn as much as possible as I know that there are great advantages with Clojure such as using refs...

I would really appreciate it if somebody could help me. Thanks!!

Answer 1

One way to translate an imperative for loop to Clojure is to use the for macro.

(for [i (range 10)] (inc i)) 

The above function will return all the numbers from 0 to 9 incremented by 1. However, it appears you simply want to iterate over a sequential collection and use each item. If that's all that you need, then you don't need to reference an index value, instead you can reference each item directly.

(for [d my-vec-of-data] (my-function d)) 

However, for this simple case, the map function would probably be a better choice because it is designed to invoke functions with arguments from collections. The following example is equivalent to the use of for above.

(map my-function my-vec-of-data) 

Both map and for return a collection of values made up of the values returned by my-function. This is because Clojure's data structures are immutable, so it's necessary to have a new collection returned. If that isn't what you need or if your function has side effects, you could use doseq instead of for, which returns nil.