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They are very different books. TAPL is a book about programming language semantics, TTAFP is a programmer-oriented book about Martin-Löf type theory.

There is very little overlap.

TAPL is definitely the book to pick up if you are interested in programming language semantics. But if you are interested in logic, dependent types, Curry-Howard correspondence there are potentially better and more modern materials than TTAFP (not to say that TTAFP is bad). If you care about formalizing programs Sofware Foundations is a much better resource, and if you care about mathematics and logic, there are resources specifically suited to that.

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What other books would you suggest? I've been reading TTAFP for a few months now and I don't like it very much. I was thinking maybe starting to read Principles of Dependent Type Theory by Angiuli and Gratzer but I'm not sure if it really covers the same area.