I read this book when I was learning functional programming. Since I started learning fp with Haskell, I couldn't figure out in the beginning how you create any meaningful programs with it. All I had were small toy programming problems from the Haskell book I was reading. This book hand-held me through learning fp and the two things that, for me, helped connect the dots were the Space Invaders type game that you build in one of the chapters of HTDP2 and Scott Wlaschin's Domain Modeling Made Functional by Scott Wlaschin. The Space Invaders game showed me how you can create a bigger program that actually is of moderate complexity by composing little functions together!
However the book is an introductory book, so there is a lot of basic stuff if you already know programming.
However the book is an introductory book, so there is a lot of basic stuff if you already know programming.