Question

I want to declare a function that takes in a function(the function also takes a element as parameter) and a list as parameters in Scheme

but the is line of code gives me error
(define (function funct(x),l)

Answer 1

In Scheme, functions are first-class citizens. Thus, you can pass a function as a parameter to another function, just like you do with any other symbol. There’s no such thing as the function keyword.

For example, to define a function called map that takes a function as an argument, and applies it to every member of the list, you could use:

(define (map f l)
  (if (null? l)
      l
      (cons (f (car l)) (map f (cdr l)))))

Then, if you had a function called add1 that you wanted to pass to map:

(define (add1 x)
  (+ x 1))

(map add1 '(1 2 3))

The result would be (2 3 4).

DEMO.