4 ms·

Swift has a stable ABI. It makes different tradeoffs than rust, but I don't think complexity is the cliff. There is a good overview at https://gankra.github.i

• kelnos 6y ago
  Swift has a stable ABI at the cost of what amounts to runtime reflection, which is expensive. That doesn't really fit with the goals of Rust, I don't think.
  • deleted 6y ago
    [deleted]
  • skohan 6y ago
    Do you have a source on this? I didn't think Swift requires runtime reflection to make calling across module boundaries work - I thought `.swiftmodule` files are essentially IR code to avoid this
    • kelnos 6y ago
      Pretty sure the link the parent (to my comment) provided explains this. It's not the same kind of runtime reflection people talk about when they (for example) use reflection in Java. It's hidden from the library-using programmer, but the calling needs to "communicate" with the library to figure out data layouts and such, and that sounds a lot like reflection to me.
  • saagarjha 6y ago
    This is misleading, especially since Swift binaries do typically ship with actual reflection metadata (unless it is stripped out). The Swift ABI does keep layout information behind a pointer in certain cases, but if you squint at it funny it's basically a vtable but for data. (Actually, even more so than non-fragile ivars are in Objective-C, because I believe actual offsets are not provided, rather you get getter/setter functions…) I don't disagree that Rust probably would not go this way, but I think that's less "this is spooky reflection" and more "Rust likes static linking and cares less about stable ABIs, plus the general attitude of 'if you're going to make an indirect call the language should make you work for it'".