7 ms·

JVM knows nothing about generics. What kind of casts are you talking about? Trampolines are a common technique to implement tailcalls on platforms that don't s

JVM knows nothing about generics. What kind of casts are you talking about? Trampolines are a common technique to implement tailcalls on platforms that don't support them natively. What are the horror stories then? Why would you bother with F# or Scala when iOS has Swift?

knocte 8y ago
> JVM knows nothing about generics. What kind of casts are you talking about? Precisely! because the bytecode doesn't know about generics (it's syntactic sugar in higher levels, i.e. Java), then casts need to be performed at runtime (e.g. when getting an item from a collection). > What are the horror stories then? https://stackoverflow.com/a/18196685/544947 https://stackoverflow.com/a/18196685/544947 > Why would you bother with F# or Scala when iOS has Swift? Haha, thanks for agreeing with me that Scala is not good in this regard. When I choose F# over Scala is because it can run in any platform. I'm not constrained.
- azolotko 8y ago
  I suppose you meant boxing/unboxing. If so, yes, that's necessary for primitive types. As for regular objects, no casts are needed. Regarding TCO, that's a well known limitation of the current Scala compiler. Hardly a "horror story". Let me assure you, there are plenty of platforms where F# is nowhere to be seen. Thus, "can run on any platform [I care about]", which is a different set for different people anyway. For example, F# does not run on JVM, does it?
  - knocte 8y ago
    Dude, JVM is not a platform but a runtime. Why is it relevant to run F# on JVM? The important thing is to run F# in any hardware/OS, that's my point. > As for regular objects, no casts are needed. Are you sure? See https://stackoverflow.com/a/10126425/544947 https://stackoverflow.com/a/10126425/544947 > Hardly a "horror story". F# doesn't have this limitation and F# does tailcalls by default instead of having to explicitly remember to decorate it with the @tailrec attribute.
    - azolotko 8y ago
      You have a pretty narrow definition of a platform. Consider https://en.m.wikipedia.org/wiki/Computing_platform https://en.m.wikipedia.org/wiki/Computing_platform Yes, you are right, I didn't consider the checkcast instruction. Yes, F# does not have this particular limitation, but has few of its own in different places. Most notably, it lacks HKT (arguably, because of CLR awareness of generics). BTW, alternative approaches to stack-safe recursion do exist in Scala. For example, https://github.com/slamdata/matryoshka https://github.com/slamdata/matryoshka
      - knocte 8y ago
        > Yes, F# does not have this particular limitation And guess what? it doesn't have it because F# doesn't run on the JVM! If it run in the JVM, it would have it. So your obsession with "runtime" as a platform not only not useful, it's asking for trouble! ;)
    - kod 8y ago
      Sounds like you are confused about what @tailrec does. @tailrec is not necessary to enable tailcalls. All the annotation does is error if a function is not able to be optimized for tail calls. The (attempt at) optimization takes place either way, you don't need the annotation unless there's some doubt in your mind.

knocte 8y ago

> JVM knows nothing about generics. What kind of casts are you talking about? Precisely! because the bytecode doesn't know about generics (it's syntactic sugar in higher levels, i.e. Java), then casts need to be performed at runtime (e.g. when getting an item from a collection). > What are the horror stories then? https://stackoverflow.com/a/18196685/544947 https://stackoverflow.com/a/18196685/544947 > Why would you bother with F# or Scala when iOS has Swift? Haha, thanks for agreeing with me that Scala is not good in this regard. When I choose F# over Scala is because it can run in any platform. I'm not constrained.

azolotko 8y ago
I suppose you meant boxing/unboxing. If so, yes, that's necessary for primitive types. As for regular objects, no casts are needed. Regarding TCO, that's a well known limitation of the current Scala compiler. Hardly a "horror story". Let me assure you, there are plenty of platforms where F# is nowhere to be seen. Thus, "can run on any platform [I care about]", which is a different set for different people anyway. For example, F# does not run on JVM, does it?
- knocte 8y ago
  Dude, JVM is not a platform but a runtime. Why is it relevant to run F# on JVM? The important thing is to run F# in any hardware/OS, that's my point. > As for regular objects, no casts are needed. Are you sure? See https://stackoverflow.com/a/10126425/544947 https://stackoverflow.com/a/10126425/544947 > Hardly a "horror story". F# doesn't have this limitation and F# does tailcalls by default instead of having to explicitly remember to decorate it with the @tailrec attribute.
  - azolotko 8y ago
    You have a pretty narrow definition of a platform. Consider https://en.m.wikipedia.org/wiki/Computing_platform https://en.m.wikipedia.org/wiki/Computing_platform Yes, you are right, I didn't consider the checkcast instruction. Yes, F# does not have this particular limitation, but has few of its own in different places. Most notably, it lacks HKT (arguably, because of CLR awareness of generics). BTW, alternative approaches to stack-safe recursion do exist in Scala. For example, https://github.com/slamdata/matryoshka https://github.com/slamdata/matryoshka
    - knocte 8y ago
      > Yes, F# does not have this particular limitation And guess what? it doesn't have it because F# doesn't run on the JVM! If it run in the JVM, it would have it. So your obsession with "runtime" as a platform not only not useful, it's asking for trouble! ;)
  - kod 8y ago
    Sounds like you are confused about what @tailrec does. @tailrec is not necessary to enable tailcalls. All the annotation does is error if a function is not able to be optimized for tail calls. The (attempt at) optimization takes place either way, you don't need the annotation unless there's some doubt in your mind.