Return an error if the parameters are empty

Question

I have function for example:

bagman(a, b) := (c:length(a), b+c)

And I would like to check parameter 'a' whether is empty. If it is empty this return information for example:

print("Parameter a is empty")

I tried this:

bagman(a, b) := (if length(a) = 0 then return(print("anything")), c:length(a), b+c)

but not work.

Answer 1

return doesn't have the same effect in Maxima as it does in other languages.

How about this:

bagman(a, b) :=
  if length(a) = 0
    then print("anything")
    else (c:length(a), b+c);

Note that I put the normal operation stuff (c:length(a), b+c) into the else so it doesn't get evaluated when length(a) = 0.