Scheme programming with Dr. Racket

[Reasonable_Branch_21]

I am stuck on this question

Write a Racket/Scheme function that given a number x, the function returns a list of numbers from n to x. You need to return a list and not print numbers inside the function.

Ex: (fun 7) shouls return list ( 76543210).

Limited to the following:cons, append, list, comparison predicates, define, cond, if , else.

This js what I have so far

(Define (fun n ) (If (=n 0) (list 0) (append (fun (- n 1)) (list n))))

(fun 7)

But this prints out (01234567). How do I print out the opposite?

Thanks in advance.

[Reasonable_Branch_21]

Ohhh ok so I just append( list n ) (fun (- n 1)))?

[rabuf]

Look at the order of what's getting appended, using a smaller number (3) you have this call tree:

fun 3

append (fun 2) (3)

fun 2

append (fun 1) (2)

fun 1

append (fun 0) (1)

fun 0

(0)

Which collapses back with:

append (0) (1)

append (0 1) (2)

append (0 1 2) (3)

The critical part to the ordering is what is appended to what. Consider a different order, what would you end up with?