How to limit the amount of characters a user can enter

(I'm using twine 2.0, Harlowe) Basically I want users to be able to choose their own names so this code seemed like a good idea:

(set: $name to (prompt: "What's your name?"))

name: $name

the problem there is no limit to how many characters the name is (it gets messy) and I don't have the slightest idea how to do so say I want it to be a max of 16 characters without a min