I took CS019 with Shriram a few years back and immediately guessed the authors based on paradigms like making testing a natural part of the language and the encouragement to use annotations. In the class, we were taught a design process for Racket that will work very well for Pyret:

1. Identify the data - create data definitions (You are gixen x and expected to produce y)

2. Write concrete examples of the data (This is hard and takes time)

3. Write contract, purpose, header for functions (contract and header are annotations in Pyret, purpose should be a commented statement)

4. Write concrete examples of the function (This is hard and takes time. This means test cases!)

5. Write the template (This may only apply to recursion in Racket, but the idea is if you're dealing with a cons, you always have the same structure of checking if a cons? or empty? and must recur)

6. Fill in the template (ie, complete the function)