Question

This is curried function that examines only the first two list elements.

fun inn list f = f(hd(list), hd(tl(list)));

What I would like to know is any ways that I can go through the rest of the list elements.
I don’t know how I make it recursive.
Can anybody help me?

Answer 1

First remark: never use hd and tl. Use pattern matching instead.

I don’t now what exactly you want your function to do, but here is one that iterates over a list and applies f to every element:

fun iter f l =
  case l of
    [] => ()
  | x::xs => (f x; iter f xs)

which can be written more concisely as

fun iter f [] = ()
  | iter f (x::xs) = (f x; iter f xs)

For what’s it worth, this very function is available in the standard basis library under the name List.app.