Question

Create a Scheme function in-order? that consumes a list of numbers numlist and
produces true if the numbers in the list appear in non-decreasing order and false
otherwise. Non-decreasing order means each number in the list is not smaller than the
previous number in the list. Your function will produce true for a list of length 0 or
1. Numbers in the list can be repeated as long as they appear consecutively.

Answer 1

It's been waaay too long since I last used Scheme, but I think this is good approximation to the answer, maybe a few minor tweaks could make it right?

Hopefully it points you in the right direction.

(define (in-order? numlist)
(if (null? (cdr numlist)
#t
(if (> (car numlist) (cadr numlist))
#f
(in-order? (cdr numlist)))))

Answer 2

Thank u very much. But i didn get that. becuase i am new in scheme and our prof said that in assignment we can just use what we learned from lecture. but i am completely lost in it. Is there any way to do this with cond? can this be fine?
(define (in-order numlist)
(cond
((empty? numlist)true)
((>=(first numlist)(first (rest numlist)))true)

( (< (first numlist) (first(rest numlist)) ) false)))

Answer 3

Yeah, if I recall correctly, cond is an 'extended if'

basically:

(define (in-order? numlist)
(cond
((empty? (cdr numlist)) #t) //if 'empty?' doesn't work, try with 'null?'
((> (car numlist) (cadr numlist)) #f) //i don't recall a 'first', but 'car' retrieves first element of a list
(else (in-order? (cdr numlist)))))

Answer 4

oh i get that Thank you )