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Programming Assignment #2                                   CS4001301
=====================================================================

1. Scheme (50pt)

	function name: inv_app
	input: 2 lists, list1 and list2
	output: inverse of list2 + inverse of list1

	Example:
	list1 = (1 2 3)
	list2 = (a b c)

	output = (c b a 3 2 1)
	  
	Put your source code in a file named pa2scheme1.scm
	and include at lease one test case for your implementation. 

2. Scheme (50pt)

	function name: dbl_atm
	input: an atom and a list
	output: a list with all occurrences of the given atom doubled 

	Example:
	atom = a
	list2 = (a (b c a (a d)))

	output = (a a (b c a a (a a d)))
	  
	Put your source code in a file named pa2scheme2.scm
	and include at lease one test case for your implementation.

Results

(inv_app '(1 2 3) '(a b c))
; => (c b a 3 2 1)

(dbl_atm 'a '(a (b c a (a d))))
; => (a a (b c a a (a a d)))

http://repl.it/languages/Scheme/

pa2scheme1.scm

(define (inverse l)
  (if (null? l)
    '()
    (append (inverse (cdr l)) (list (car l)))
  )
)

(define (inv_app l1 l2)
  (append (inverse l2) (inverse l1))
)

; (inv_app '(1 2 3) '(a b c))
; => (c b a 3 2 1)

pa2scheme2.scm

(define (dbl_atm atom list2)
  (if (null? list2)
    '()
    (append
      (if (pair? (car list2))
        (list (dbl_atm atom (car list2)))
        (if (equal? atom (car list2))
          (list (car list2) (car list2))
          (list (car list2))
        )
      )
      (dbl_atm atom (cdr list2))
    )
  )
)

; (dbl_atm 'a '(a (b c a (a d))))
; => (a a (b c a a (a a d)))