Exercise 159: You know about first and rest from BSL, but BSL+ comes with even more selectors than that....

Exercise 159: You know about first and rest from BSL, but BSL+ comes with even more selectors than that. Determine the values of the following expressions:

1. (first (list 1 2 3))
2. (rest (list 1 2 3))
3. (second (list 1 2 3))

Find out from the documentation whether third, fourth, and fifth exist.



This is a very straight forward exercise. As always with exercises of this type the hardest thing is making yourself do the exercise rather than just pasting the expressions into racket and seeing what they evaluate to.

I did not do as well as I expected - I got the first and third questions wrong. I was expecting them to return a list instead of the element.

A quick look at the documentation shows that not only do third, fourth and fifth exist, but so do sixth, seventh, eighth, nineth and tenth.

;(first (list 1 2 3))
(check-expect (first (list 1 2 3))
              1)


;(rest (list 1 2 3))
(check-expect (rest (list 1 2 3))
              (list 2 3))


;(second (list 1 2 3))
(check-expect (second (list 1 2 3))
              2)