Question

I am trying to create a function that takes two functions as arguments and executes both of them.

I tried using cond, but it only executes action1.

(define seq-action
  (lambda (action1 action2)
    (cond
     ((procedure? action1) (action1))
     ((procedure? action2) (action2)))))

I feel like it shouldn’t be too hard to run one after the other. They don’t need to run at the same time.

I have tried simply (action1) (action2) side-by-side, but it only returns action2. Here is what I define for action1 and action2:

(define ax 
  (lambda ()
    (+ 1 2)))
(define bx 
  (lambda ()
    (+ 5 2)))

Answer 1

Executing one procedure after the other is as simple as this:

(define seq-action
  (lambda (action1 action2)
    (action1)
    (action2)))

However, the above will only return the result of the last procedure. If you need both results then return a list with the values, like this:

(define seq-action
  (lambda (action1 action2)
    (list (action1) (action2))))

Alternatively, you could return multiple values simultaneously using the values procedure:

(define seq-action
  (lambda (action1 action2)
    (values (action1) (action2))))

For retrieving both values after calling the last version, you need to use let-values.