> Then there's the confusion between lambdas and closures. They are not the same thing. Lambdas are simply anonymous functions, usually with funny syntax to make them easier to write in line. Closures are functions with data imported from an outer scope. Some languages separate the two.

I remember a few years ago saying that I found the naming of anonymous functions in Rust "closures" rather than "lambdas" weird since most of the time they're used they don't close over anything. Someone responded by saying that all of them closed over something, it just sometimes was unit (the empty tuple type in Rust, essentially the equivalent of "void" when used as a return type). I didn't find it super compelling at the time, although over the years learning more about how much the ownership and borrowing system influenced the way that closures needed to be used in Rust (e.g. having separate traits for functions that close over shared borrows, mutable borrows, and owned values) has made me at least understand why the fact that they close over things is worth emphasizing.