3 ms·

While it may be convenient, it's truly worrying such (EDIT: was "many") syntactic special cases are going into Rust at this point. (It may be the case that the

While it may be convenient, it's truly worrying such (EDIT: was "many") syntactic special cases are going into Rust at this point. (It may be the case that these things absolutely cannot be handled in a systematic way in a no-GC/no-runtime language, but I'd really like to see some evidence that this is the case.)

steveklabnik 10y ago
Which ones specifically worry you? I can't think of many, but I am also incredibly biased.
- lomnakkus 10y ago
  Sorry, phrasing was bad. I've edited.
  - steveklabnik 10y ago
    No worries, it happens. What worries you about it? What things need to be "handled in a systematic way"? Are you just generally opposed to any new syntax in languages or something?
    - lomnakkus 10y ago
      See my other comment; https://news.ycombinator.com/item?id=12924880 https://news.ycombinator.com/item?id=12924880
Manishearth 10y ago
> how many I can only think of one redundant feature, and that is the ? operator. This is because `try!` gets used very often in in a lot of code. I can only think of one syntactic feature (redundant or otherwise) that doesn't get used often and that is HRTB(`for<'a>`), which needs to be there to be able to specify some types correctly (but is very rare).
- lomnakkus 10y ago
  If you have enough abstraction capability (HKTs, for example), try! is also redundant... and you can instantly generalize to anything that isn't necessarily a `Result` but has the same general structure. By special-casing now, one almost-certainly[1] closes the opportunity for future consolidation. [1] I say almost because it's not necessarily a done deal, but migration gets exponentially harder the longer a language has been "out in the wild". GHC/Haskell has gone through a similar upheaval in the last 1-2 years and it wasn't pretty... but ultimately it seems to at least have survived, so there's that.
  - steveklabnik 10y ago
    While this is true, it's not clear if Rust will ever get the stuff needed for do notation, some believe that it's impossible. And people need to reduce their error-handling boilerplate today. Rust will certainly have warts. Maybe someday in the future we'll feel like this is one of them, maybe not. :)
    - lomnakkus 10y ago
      > it's not clear if Rust will ever get the stuff needed for do notation, some believe that it's impossible True, and I think I acknowledged as much in my original comment. > And people need to reduce their error-handling boilerplate today. Indeed, I'm just (vaguely) worried about Rust being painted into a corner. As I said in my OP, it may actually be an unavoidable corner -- I hope not, but as you say... I guess we'll see :).
  - Manishearth 10y ago
    > and you can instantly generalize to anything that isn't necessarily a `Result` but has the same general structure. > > closes the opportunity The door isn't closed for this, `?` works with a "carrier" trait, which lets you extend the operator. Now, it's currently unstable, so right now you can't use it, but the door is wide open for the design of `Carrier` to be finalized. This was explicitly discussed and thought out before ? was stabilized. It's just that ? was stabilized before Carrier. The compiler knows nothing about `Result`. There are very few structs that it knows anything about, and these all have to do with atomics or `UnsafeCell` or other intrinsic-based primitives that you don't need to reimplement out-of-tree anyway. It knows a few traits, like Add and Copy and Carrier, which can be used to extend operators and stuff.
nercury 10y ago
Not sure what you are talking about - it is the first bigger syntax addition since 1.0, and I actually want more.
bascule 10y ago
This is a standard operator found in many programming languages, including ones with GC: https://en.wikipedia.org/wiki/Safe_navigation_operator https://en.wikipedia.org/wiki/Safe_navigation_operator To the contrary of what you're suggesting, I think Rust has done a great job eliminating a lot of the previous special-cased syntax and rebuilding things upon a simplified set of core primitives.
- masklinn 10y ago
  It has very different semantics in Rust than it does elsewhere though.

steveklabnik 10y ago

Which ones specifically worry you? I can't think of many, but I am also incredibly biased.

lomnakkus 10y ago
Sorry, phrasing was bad. I've edited.
- steveklabnik 10y ago
  No worries, it happens. What worries you about it? What things need to be "handled in a systematic way"? Are you just generally opposed to any new syntax in languages or something?
  - lomnakkus 10y ago
    See my other comment; https://news.ycombinator.com/item?id=12924880 https://news.ycombinator.com/item?id=12924880

Manishearth 10y ago

> how many I can only think of one redundant feature, and that is the ? operator. This is because `try!` gets used very often in in a lot of code. I can only think of one syntactic feature (redundant or otherwise) that doesn't get used often and that is HRTB(`for<'a>`), which needs to be there to be able to specify some types correctly (but is very rare).

lomnakkus 10y ago
If you have enough abstraction capability (HKTs, for example), try! is also redundant... and you can instantly generalize to anything that isn't necessarily a `Result` but has the same general structure. By special-casing now, one almost-certainly[1] closes the opportunity for future consolidation. [1] I say almost because it's not necessarily a done deal, but migration gets exponentially harder the longer a language has been "out in the wild". GHC/Haskell has gone through a similar upheaval in the last 1-2 years and it wasn't pretty... but ultimately it seems to at least have survived, so there's that.
- steveklabnik 10y ago
  While this is true, it's not clear if Rust will ever get the stuff needed for do notation, some believe that it's impossible. And people need to reduce their error-handling boilerplate today. Rust will certainly have warts. Maybe someday in the future we'll feel like this is one of them, maybe not. :)
  - lomnakkus 10y ago
    > it's not clear if Rust will ever get the stuff needed for do notation, some believe that it's impossible True, and I think I acknowledged as much in my original comment. > And people need to reduce their error-handling boilerplate today. Indeed, I'm just (vaguely) worried about Rust being painted into a corner. As I said in my OP, it may actually be an unavoidable corner -- I hope not, but as you say... I guess we'll see :).
- Manishearth 10y ago
  > and you can instantly generalize to anything that isn't necessarily a `Result` but has the same general structure. > > closes the opportunity The door isn't closed for this, `?` works with a "carrier" trait, which lets you extend the operator. Now, it's currently unstable, so right now you can't use it, but the door is wide open for the design of `Carrier` to be finalized. This was explicitly discussed and thought out before ? was stabilized. It's just that ? was stabilized before Carrier. The compiler knows nothing about `Result`. There are very few structs that it knows anything about, and these all have to do with atomics or `UnsafeCell` or other intrinsic-based primitives that you don't need to reimplement out-of-tree anyway. It knows a few traits, like Add and Copy and Carrier, which can be used to extend operators and stuff.

nercury 10y ago

Not sure what you are talking about - it is the first bigger syntax addition since 1.0, and I actually want more.

bascule 10y ago

This is a standard operator found in many programming languages, including ones with GC: https://en.wikipedia.org/wiki/Safe_navigation_operator https://en.wikipedia.org/wiki/Safe_navigation_operator To the contrary of what you're suggesting, I think Rust has done a great job eliminating a lot of the previous special-cased syntax and rebuilding things upon a simplified set of core primitives.

masklinn 10y ago
It has very different semantics in Rust than it does elsewhere though.