I have recently become extremely interested in understanding and proving aspects of (functional) programming languages.
However as I dive deeper in, things like $\lambda$ calculus, category theory, and denotational semantics are a little difficult to grok without proper explanation.
I read SICP (quite an enlightening book) but I'm looking to dive deeper into the theory of functional programming. Are there any books/blogs/sites/you-name-it that would discuss the theory of functional programming languages from the ground up?