I highly recommend How to Design Programs. I recall being repeatedly mind blown working through the book. It was great fun. The authors start by composing pure

I highly recommend How to Design Programs. I recall being repeatedly mind blown working through the book. It was great fun. The authors start by composing pure functions. IIRC you get quite far before you have to do any mutation. Take a look! https://htdp.org/2003-09-26/Book/curriculum-Z-H-5.html https://htdp.org/2003-09-26/Book/curriculum-Z-H-5.html