4 ms·

There must be some interesting reason why ".." and not the more common "..." - I wonder what?

by cannam 10y ago

the_duke 10y ago
They probably 'copied' Haskell here, which also uses "..".
- pdexter 10y ago
  Haskell doesn't have this feature though. I mean it does, but you can just leave out the ones you don't want matched, you don't have to put in any dots.
echelon 10y ago
It's less to type. The double period is already used for lots of other things in the language, so it feels like the correct choice.
swsieber 10y ago
Reading through, they treat a range (like 1 .. 10 ) as pattern matching 1 2 3 4 5 6 7 8 9 10, with .. representing 2 3 4 5 6 7 8 9. In that light, it actually makes sense.
- cannam 10y ago
  Ah of course, that is quite widely used (e.g. Perl). If you already have that, I can see why you'd reuse the same token. (edit: ok, I see from other replies that it's not that simple)
- anuragsoni 10y ago
  Minor correction, to match a range the syntax would be 1 ... 10
tatterdemalion 10y ago
No particular reason. `..` and `...` both exist in the language, `..` is exclusive range and `...` is inclusive range. `..` is only in expressions right now, whereas `...` is only in patterns. Eventually, both will be available everywhere, possibly. At very least, `..` in patterns is getting added soon. Since this is a pattern thing, probably `..` was chosen when `...` was the only range available in patterns, to distinguish this from that range pattern more. However, `..` will now be available in patterns, so its just historical. (This is a longstanding feature, what's changed is just making it apply to more patterns.)
anuragsoni 10y ago
I've seen the "..." used for matching a range of values, whereas ".." is used in other places where we disregard a value while patter matching. I'm sure someone from the rust team can give a better answer, but to me this change looks like it was just bringing the pattern matching for structs to be consistent with other uses of ".." Relevant RFC: https://github.com/rust-lang/rfcs/blob/master/text/1492-dotdot-in-patterns.md https://github.com/rust-lang/rfcs/blob/master/text/1492-dotd...

There must be some interesting reason why ".." and not the more common "..." - I wonder what?

by cannam 10y ago

There must be some interesting reason why ".." and not the more common "..." - I wonder what?

the_duke 10y ago

They probably 'copied' Haskell here, which also uses "..".

pdexter 10y ago
Haskell doesn't have this feature though. I mean it does, but you can just leave out the ones you don't want matched, you don't have to put in any dots.

echelon 10y ago

It's less to type. The double period is already used for lots of other things in the language, so it feels like the correct choice.

swsieber 10y ago

Reading through, they treat a range (like 1 .. 10 ) as pattern matching 1 2 3 4 5 6 7 8 9 10, with .. representing 2 3 4 5 6 7 8 9. In that light, it actually makes sense.

cannam 10y ago
Ah of course, that is quite widely used (e.g. Perl). If you already have that, I can see why you'd reuse the same token. (edit: ok, I see from other replies that it's not that simple)
anuragsoni 10y ago
Minor correction, to match a range the syntax would be 1 ... 10

tatterdemalion 10y ago

No particular reason. `..` and `...` both exist in the language, `..` is exclusive range and `...` is inclusive range. `..` is only in expressions right now, whereas `...` is only in patterns. Eventually, both will be available everywhere, possibly. At very least, `..` in patterns is getting added soon. Since this is a pattern thing, probably `..` was chosen when `...` was the only range available in patterns, to distinguish this from that range pattern more. However, `..` will now be available in patterns, so its just historical. (This is a longstanding feature, what's changed is just making it apply to more patterns.)

anuragsoni 10y ago

I've seen the "..." used for matching a range of values, whereas ".." is used in other places where we disregard a value while patter matching. I'm sure someone from the rust team can give a better answer, but to me this change looks like it was just bringing the pattern matching for structs to be consistent with other uses of ".." Relevant RFC: https://github.com/rust-lang/rfcs/blob/master/text/1492-dotdot-in-patterns.md https://github.com/rust-lang/rfcs/blob/master/text/1492-dotd...