The tail end of this book ended up going quickly, for a couple reasons.
One was that I saved the optional chapters for last, and the optional chapters are much easier than the main chapters.
The other was that I began listening to someone's advice about following 80/20 principle when it comes to exercises-- literally only do 20% of the exercises to get 80% of the benefit. Frankly, I'm not convinced, but my life has other priorities that began to impinge on my enjoyment of this time investment.
I dont think I skipped an exercise that i didnt struggle with for an hour. Moreover, to quote bob Harper "just because you can play the video game known as coq doesmt mean you know type theory"-- what if it's the case that by becoming reliant on tactics I've poisoned my mind??
I'm appreciative of what I've learned about programming languages on this journey. Now, i have to consolidate the gains: either by rolling my own PLs in coq or maybe by reading the agda version for a tactic-free approach.
I'm a little unsatisfied and I'm likely to return to the book to tie up loose ends-- in particular, the typechecking chapter kicked my ass. I have a list of everything I didnt complete and it will always haunt me.