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I mean, GP said "you can't have routers" and maybe I'm being dense by interpreting that as "never or almost never," but even with a generous "too hard to be pra

by kortex 5y ago

I mean, GP said "you can't have routers" and maybe I'm being dense by interpreting that as "never or almost never," but even with a generous "too hard to be practical," I still don't think it's correct. And I explicitly said "escape hatch" meaning language feature. You don't need that much indirection to get routers in Haskell, Rust, Go, C, C++... like I fail to see how implementing routers are a barrier in strict type system languages. Is it easier in python or js? Sure. can't? hardly. E: here's some vtable dispatch (unless that doesn't count as "dynamic dispatch") in Rust. Looks really straightforward. https://doc.rust-lang.org/1.8.0/book/trait-objects.html https://doc.rust-lang.org/1.8.0/book/trait-objects.html

ukj 5y ago
What C++, Haskell, Rust, Go etc. call "dynamic dispatch" is what a router calls "static routing". The defining characteristic is that the lookup table is pre-determined and immutable at runtime. What routers call "dynamic routing" is having the lookup table mutable at runtime. There can be no equivalent to that in type-safe languages because when you mutate the dispatch table you lose type-safety.
- kortex 5y ago
  > What routers call "dynamic routing" is having the lookup table mutable at runtime. > There can be no equivalent to that in type-safe languages because when you mutate the dispatch table you lose type-safety. That's exactly what I mean by escape hatches. Rust has unsafe. You can write a WTF FastInverseSqrt in Rust. You shouldn't 99% of the time. But you can. Rust also has Box, Rc, Arc, and other tools. I'm not fluent enough in rust to know how to, but I'm quite confident and will eat my hat if you can't accomplish what is effectively a mutable vtable dispatch in Rust. But also...why? Yeeting a function call into the void without any type knowledge seems way more bug-prone than interface/trait-based dispatch, to what benefit? Save developer time? I've spent countless dev-days of my life I won't get back debugging exactly this kind of dynamic-dispatched, json-dsl, frankly loosey-goosey untyped bullshit. There's so many better ways.
  - ukj 5y ago
    Well isn't that's precisely my point! "unsafe" turns off your compiler's guard rails. You CAN accomplish mutable vtable dispatch and in doing so you will undermine Rust's type-safety! Yeeting a function call into the void is what async network clients usually do. You will soon get a result. Maybe.
    - dang 5y ago
      Would you please stop? Regardless of how right you are or feel you are, we don't want long, tedious flamewars like this and you did more than anyone else to prolong it. Dozens of comments is beyond excessive. https://news.ycombinator.com/newsguidelines.html https://news.ycombinator.com/newsguidelines.html

by kortex 5y ago

ukj 5y ago

What C++, Haskell, Rust, Go etc. call "dynamic dispatch" is what a router calls "static routing". The defining characteristic is that the lookup table is pre-determined and immutable at runtime. What routers call "dynamic routing" is having the lookup table mutable at runtime. There can be no equivalent to that in type-safe languages because when you mutate the dispatch table you lose type-safety.

kortex 5y ago
> What routers call "dynamic routing" is having the lookup table mutable at runtime. > There can be no equivalent to that in type-safe languages because when you mutate the dispatch table you lose type-safety. That's exactly what I mean by escape hatches. Rust has unsafe. You can write a WTF FastInverseSqrt in Rust. You shouldn't 99% of the time. But you can. Rust also has Box, Rc, Arc, and other tools. I'm not fluent enough in rust to know how to, but I'm quite confident and will eat my hat if you can't accomplish what is effectively a mutable vtable dispatch in Rust. But also...why? Yeeting a function call into the void without any type knowledge seems way more bug-prone than interface/trait-based dispatch, to what benefit? Save developer time? I've spent countless dev-days of my life I won't get back debugging exactly this kind of dynamic-dispatched, json-dsl, frankly loosey-goosey untyped bullshit. There's so many better ways.
- ukj 5y ago
  Well isn't that's precisely my point! "unsafe" turns off your compiler's guard rails. You CAN accomplish mutable vtable dispatch and in doing so you will undermine Rust's type-safety! Yeeting a function call into the void is what async network clients usually do. You will soon get a result. Maybe.
  - dang 5y ago
    Would you please stop? Regardless of how right you are or feel you are, we don't want long, tedious flamewars like this and you did more than anyone else to prolong it. Dozens of comments is beyond excessive. https://news.ycombinator.com/newsguidelines.html https://news.ycombinator.com/newsguidelines.html