Lesson 3: Validation functions
- 15 minutes
In this lesson we get into the code that we will stay with through the rest of the course. To start, we need to write three functions. One checks a
String for a maximum length. The second verifies that a
String input is all alphanumeric characters – no special characters allowed in our passwords! The third will strip any leading white space off of a
String input. All three return a
Maybe String, so invalid inputs are all
Nothing. This lesson ends with an exercise for the viewer.