Exercises for the book - The Little Typer

Exercises were lovingly curated by Paul Cadman

Getting Started

1. Install Racket
2. Open DrRacket
3. File -> Install Package
4. In the package name field, type pie and then click the Install button.
5. To use Pie, begin a file with #lang pie in DrRacket.
6. Testing Pie Programs

Help

• replace in Chapter 9 was quite hard for me to grasp, but I wasn't the only one. Andrew Helwer has written up a blog post as a preamble to Chapter 9, that I would recommend reading before reading Chapter 9. I also finally came up with a way to understand and use it and it seems like everyone in the study group came up with their own unique way. See discussion in the Google Group or a print out of the discussion if you don't have permission.

• Exercise 10.2 and 10.3 might be easier after reading Chapter 12.

Other Observations

• rec-Nat and rec-List are paramorphisms, see Nat.hs and List.hs. Exercises from Chapter 3, 4 and 5 were rewritten using these implementations.

  For more information on recursion schemes, see An introduction to recursion schemes - Patrick Thomson

• same is a Functor and cong is fmap, see Equal.hs