Elm tutorial too hard - how to check for upper case?

I am trying to learn Elm, but the official tutorial got too hard for me.

In the forms tutorial the exercise is to check if the password contains upper case letters, lower case letters and digits.

That is all stuff what I haven't learned so far...

In other languages I would create a function/method to go through a string and check every single char.

But we haven't learned for or while loops yet... or even other stuff like Char.

Can someone please help me.