It is a bit weird, and it's one of the parts of the language still being worked on [1]. What it comes down to is that while they're both bits of machine code b

It is a bit weird, and it's one of the parts of the language still being worked on [1]. What it comes down to is that while they're both bits of machine code being executed, their environments are different. I'm a bit out of date as there's been movement in this area since I've written much "hard core" Rust code, but the basic problem is that what the grandparent poster calls an "anonymous function" is a closure, with a captured environment. Thus said closure has different interactions with lifetimes, memory management, and program safety. Since safety and soundness is one of the primary goals of Rust, problems like this do crop up and are surely what I see as the hardest part of designing a usable language. [1] http://smallcultfollowing.com/babysteps/blog/2013/10/10/fn-types-in-rust/ http://smallcultfollowing.com/babysteps/blog/2013/10/10/fn-t...