;Assuming listofLists is a list of lists,
;This function returns a list composed of the first
;element of each list.


(define getFirstAtomOfEach 
  (lambda (listofLists)
    (getFirstAtomOfEach_recurse listofLists ())
  )
)


(define getFirstAtomOfEach_recurse 
  (lambda (listofLists listofFirstAtoms)
    (cond 
      ((null? listofLists) 
        (reverse listofFirstAtoms)
      )
      (else 
        (getFirstAtomOfEach_recurse 
          (cdr listofLists) 
          (cons (car (car listofLists)) 
                 listofFirstAtoms
          )
        )       
      )
    )
  )
)


;============== Unit Tests ======================
(load "test.scm")
(define msg "getFirstAtomOfEach")
(test msg 
      (getFirstAtomOfEach '((a aa) (b bb bbb) (c cc)))
      '(a b c)
)
(test msg 
      (getFirstAtomOfEach '((a aa)))
      '(a)
)