His course covers the ideas behind so-called functional programming paradigm - high-order functions , environments, lexical scooping, closures and the standard idioms, including currying and lazyness. This course about concepts behind programming languages, not languages themselves.
Yeah. That's an introduction. You basically didn't mention anything that wasn't covered in the untyped lambda calculus at the beginning of the last century.
Inside a computer everything is a number - sometimes a number represent itself, sometimes it is a pointer (a number of a byte, an offset) and sometimes it is a code, a number of an unicode character, etc.
The key idea there is that a pointer points to everything, value has a type, not a pointer. There are no pointers-to-integers along with pointers-to-booleans and pointers-to-strings. There are only numbers here.
Having one kind of pointer for all is the semantics of untyped lamda calculus. We could cons everything with everything, we could have heterogeneous lists, tuples, whatever.
Well, it seems that untyped lambda calculus are good-enough.) Perfection is achieved when there is nothing to remove, and not adding features is sometimes more wise.
