I agree that it is syntactic salt and that the design is to discourage mutability. I actually appreciate that point as a programmer.
w.r.t. this specific issue: I think what concerns me is that it is quite a high burden for new programmers (I teach COSC1xx courses to new students so I have some idea about the level of new programmers). For example, you need to know more detail about what is going on - new programmers would find that difficult as it is one more concept to overflow their heads. Adding "var" as a keyword identically maps to new programmer's expectations from JavaScript. Writing a program entirely using "var" wouldn't cause any problems right? But, could be optimised more (potentially) if using "let" for immutable parts. Anyway, I'm not convinced either way, I'm not sure I see the entire picture yet. But, if I was writing code, I'd certainly get sick of writing "let mut" over and over again - and looking at existing rust examples, that certainly seems like the norm.. On 30 January 2014 15:59, Samuel Williams <[email protected]>wrote: > I guess the main gain would be less typing of what seems to be a > reasonably common sequence, and the formalisation of a particular semantic > pattern which makes it easier to recognise the code when you visually > scanning it. > > > On 30 January 2014 15:50, Kevin Ballard <[email protected]> wrote: > >> On Jan 29, 2014, at 6:43 PM, Brian Anderson <[email protected]> >> wrote: >> >> > On 01/29/2014 06:35 PM, Patrick Walton wrote: >> >> On 1/29/14 6:34 PM, Samuel Williams wrote: >> >>> Perhaps this has been considered already, but when I'm reading rust >> code >> >>> "let mut" just seems to stick out all over the place. Why not add a >> >>> "var" keyword that does the same thing? I think there are lots of good >> >>> and bad reasons to do this or not do it, but I just wanted to propose >> >>> the idea and see what other people are thinking. >> >> >> >> `let` takes a pattern. `mut` is a modifier on variables in a pattern. >> It is reasonable to write `let (x, mut y) = ...`, `let (mut x, y) = ...`, >> `let (mut x, mut y) = ...`, and so forth. >> >> >> >> Having a special "var" syntax would defeat this orthogonality. >> > >> > `var` could potentially just be special-case sugar for `let mut`. >> >> To what end? Users still need to know about `mut` for all the other uses >> of patterns. This would reserve a new keyword and appear to duplicate >> functionality for no gain. >> >> -Kevin >> _______________________________________________ >> Rust-dev mailing list >> [email protected] >> https://mail.mozilla.org/listinfo/rust-dev >> >> >
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