I'm looking through An Introduction to Functional Programming Systems Using Haskell by Davie and one of the exercises is

Define a function f such that

f(x) = x + 3 (mod 5)

Make a version that elaborates cases, as well as a straightforward way.

I'm not really sure what's being asked, so this is what I've come up with

myMods xs = map (\x -> (x + 3) `mod` 5) xs

> myMods [1..20]

[4,0,1,2,3,4,0,1,2,3,4,0,1,2,3,4,0,1,2,3]

but when he says make a version that elaborates cases I'm not sure what more there is to do.

What am I missing?