[rust-dev] "let mut" <-> "var"
banderson at mozilla.com
Thu Jan 30 16:32:13 PST 2014
I'm convinced by this thread that this issue should be put to bed
forever. I added a note to the design faq issue:
On 01/30/2014 03:20 PM, Benjamin Striegel wrote:
> > https://github.com/mozilla/rust/issues/2643
> I came here to post that link, you beat me to it. :)
> Highly, vehemently, frothing-at-the-mouthly against adding `var` as
> sugar for `let mut`. You can see from reading that issue that I too
> was once a fan of getting rid of `let mut`, but after using Rust in
> the years since I can see how lovely the current setup is. I was the
> one who initiated the widespread grepping recently that found that
> `let` was three times more common than `let mut`, and I admit I was
> surprised to find that immutability was so completely dominant.
> Immutability is crucial to Rust. Mutability *must* be explicit. Not
> having to ever worry about const-correctness is icing on the cake.
> Adding an alternative form for `let mut` would go completely against
> the spirit of the language.
> On Thu, Jan 30, 2014 at 12:18 PM, Tim Chevalier
> <catamorphism at gmail.com <mailto:catamorphism at gmail.com>> wrote:
> I'm surprised that no one has mentioned so far that there was a
> previous, exhaustive, discussion of this question on github:
> As far as I can tell, this thread adds nothing new that wasn't already
> discussed in the comments on #2643. So that strongly suggests to me
> that nothing needs to be changed.
> On Thu, Jan 30, 2014 at 8:49 AM, Steven Fackler
> <sfackler at gmail.com <mailto:sfackler at gmail.com>> wrote:
> > The Zen of Python also says "There should be one-- and
> preferably only one
> > --obvious way to do it."
> > Steven Fackler
> > On Thu, Jan 30, 2014 at 11:35 AM, Donaldo Fastoso
> > <donquestion at rocketmail.com <mailto:donquestion at rocketmail.com>>
> >> I like python's rational of "consenting adults": Give people
> the tools
> >> to do the right thing, if they still want to hurt themselves,
> they may
> >> have a good reason, or they are better of dead! ;-)
> >> I would argue, that people choosing Rust over C/C++ are choosing it
> >> BECAUSE of safety measures like immutability and wouldn't need
> >> overbearing lectures.
> >> In all honesty it's not the TYPING of three additional chars
> "let mut",
> >> but the READING. It interrupts the flow of reading, or better: it's
> >> a bump in the flow of scanning. Source-Code is not prosa, you
> have to
> >> actively follow the train of thought and guess the intentions
> of the
> >> author. So improving READABILITY would really be nice, especially
> >> for people coming from other languages. They would probably try to
> >> learn by reading the source from experienced programmers.
> >> In this case i would also advice against the use of "var", instead
> >> of "let mut", but omitting "let" and leave it to "mut" would be
> >> easier to read and understand.
> >> so
> >> "let mut x, y;"
> >> would become:
> >> "mut x;"
> >> "let y;"
> >> which would take a possible interpretation-ambiguity away from the
> >> single "let mut x, y", which can be read either as "let mut" for x
> >> and y, or "let mut x" and "let y"!
> >> So imho "let mut" has at least two pitfalls:
> >> 1) read-bump
> >> 2) ambiguity.
> >> AFAIK you did a remarkable good job so far, and i have all the
> >> you are considering all arguments before coming to a decision.
> >> Even if some thoughts of the thoughts come form the bad smelling
> >> "lurker"-fraction, which do nothing but making comments about
> things they
> >> possible can't understand! ;-)
> >> Regards,
> >> Don
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> Tim Chevalier * http://catamorphism.org/ * Often in error, never
> in doubt
> "If you are silent about your pain, they'll kill you and say you
> enjoyed it."
> -- Zora Neale Hurston
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