[rust-dev] "let mut" <-> "var"

Brian Anderson banderson at mozilla.com
Wed Jan 29 18:43:13 PST 2014


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`.


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