> Can anyone recommend any other such middle ground resources on type systems and type system theory?
I really enjoyed Pierce's Types and Programming Languages. As I recall, he starts with the simple untyped lambda calculus, and builds a motivation for a type system, as well as the type system itself. It then switches to ML (or perhaps OCaml) and shows how features can be built-in to a type system as they're described.
I think it's a good fit - I know you said not heavy academic texts, but I don't think it's too heavy, it's at the level of an introductory undergraduate course. (Beware Advanced Topics in ~ by the same author which probably is on the heavier end, I don't know, I haven't braved it yet!)
I really enjoyed Pierce's Types and Programming Languages. As I recall, he starts with the simple untyped lambda calculus, and builds a motivation for a type system, as well as the type system itself. It then switches to ML (or perhaps OCaml) and shows how features can be built-in to a type system as they're described.
I think it's a good fit - I know you said not heavy academic texts, but I don't think it's too heavy, it's at the level of an introductory undergraduate course. (Beware Advanced Topics in ~ by the same author which probably is on the heavier end, I don't know, I haven't braved it yet!)