9 ms·

Hot Reloading in Swift

99 points by mgrayson 4y ago

lisper 4y ago
This is one of the main reasons I like Common Lisp, and Clozure CL in particular, which has a blazing fast compiler: my debug cycles are measured in seconds. Over dozens or hundreds of cycles it really adds up.
- Cthulhu_ 4y ago
  Isn't lisp a scripting language though? Different flavor of language. I mean JS used to be a scripting language, but thanks to Reasons there's a lot more involved to get fast development cycles.
  - lisper 4y ago
    > Isn't lisp a scripting language though? No. Where did you get that idea?
markhelo 4y ago
"Microsoft has been killing it over the last decade regarding dev tooling and experience, so it is not a big surprise." To be fair, for all the flack Microsoft got/gets, the dev tooling for Windows ecosystem is miles ahead of anyone else and world class. Perhaps I am biased as I worked there at one point, but since I don't anymore, I have also seen tooling from Apple and Google and they are a couple of decades behind. There is some truth to why Steve Ballmer went ballistic with his Developer chant, they really built great tooling for developers.
- deleted 4y ago
  [deleted]
- game-of-throws 4y ago
  MS had "edit and continue" (aka hot reloading) in Visual Basic in the 90s. Then I switched to other languages and I've gone without it the rest of my career. I don't think VB the language is very good, but the developer experience still beats anything I've used since then.
- pjmlp 4y ago
  With the caveat that Borland is even better before they decided to focus on enterprise customers, and went through all those acquisitions and name changes. Delphi and C++ Builder are still unmatched in many capabilities on the Visual Studio side.
- refulgentis 4y ago
  This is an odd response given the article calls at Google as having the gold standard for this, and I'm not sure there's any equivalent at all at MS? They push Flutter too
  - jayd16 4y ago
    You mean like this? https://docs.microsoft.com/en-us/visualstudio/debugger/hot-reload?view=vs-2022 https://docs.microsoft.com/en-us/visualstudio/debugger/hot-r... "Microsoft has been killing it over the last decade regarding dev tooling and experience" was a direct quote from the article.
    - refulgentis 4y ago
      Thank you! That context makes it much clearer
  - m_at_goog 4y ago
    Maybe they mean internal at Google? Internal Google tooling is pretty hit or miss, especially with older products that are a patch work of different internal only Google stacks.
  - pjmlp 4y ago
    The gold standard are Smalltalk and Common Lisp environments, that people pushing Flutter tend to ignore on their marketing, as they ignored the existing work on Java and .NET ecosystems.
- tester756 4y ago
  There's emoji after "killing it" I believe it changes meaning of this sentence.
  - frosted-flakes 4y ago
    No it doesn't? In that context, "killing it" means doing a great job.
- can16358p 4y ago
  Agreed. Visual Studio is an excellent piece of software, along with .NET and C#. I think Apple isn't that bad either, yet still behind MS. Google is a disaster though. A few weeks ago I needed to download Android Studio. Downloaded a clean stable release from its official site for my machine (M1 Mac). From that clean install literally erroring while trying to launch AVDs to cryptic error messages about JDK environments, Google's the only IDE out of these big three where I get countless of errors and losing hours on something that literally doesn't work out of the box. Hope Xcode and VS never becomes something crappy like Android Studio.
musesum 4y ago
Ironically, I think Brad Cox had something like this in mind, after coming up with Objective C. Or at least, pluggable components [1] I wonder what the threat model would be? Injectable binaries seem like a decent attack vector. But, if we're talking 2040, maybe a signable Merkle tree would do the trick. Meanwhile, have been experimenting with recompiling Metal code at runtime. Was kinda fun with ObjC/C++/OpenGL, a few years ago. [1] https://thenewstack.io/objective-cs-roots-in-the-life-of-brad-cox/ https://thenewstack.io/objective-cs-roots-in-the-life-of-bra...
- dmix 4y ago
  Erlang has had hotloading for a long time and seems to be fine security wise AFAIK.
  - kaba0 4y ago
    Hot reloading’s quality (and to a degree, security) depends mostly on how fine-grained a change can be. The reason Lisp-REPl workloads are so well loved is that very small scopes can be changed easily, Erlang also has a sane encapsulation that can be swapped without much fuss.
    - jjtheblunt 4y ago
      just wanted to say i really like the clarity of that explanation
  - melony 4y ago
    Most of (traditional) Erlang deploymens are in embedded systems. They have a different threat model.
  - toast0 4y ago
    Erlang has a very limited security model. In the default distribution, any process on any node can spawn a process on any other connected node to run any function --- you can send the function too. Modules can have a function to run on load, too. Loading an untrusted module is asking for that module to take over your whole system. Best to make sure nobody unauthorized can do that.
leecommamichael 4y ago
You can hot-reload any language that can load a dynamic library. Compile the hot-reloadable portion of your app to a dylib and use a hotkey to reload the lib.
- mananaysiempre 4y ago
  That is only the beginning, isn’t it? The hard part is figuring out how to migrate state, and clearly saying “no” when that fails instead of leaving the user to debug a configuration that could not have arisen had the new code been started from a clean slate. (I don’t think that’s actually possible to disprove, even, but at the very least guaranteeing that memory contains the types the new code thinks it does would be good.)

99 points by mgrayson 4y ago

This is one of the main reasons I like Common Lisp, and Clozure CL in particular, which has a blazing fast compiler: my debug cycles are measured in seconds. Over dozens or hundreds of cycles it really adds up.

Cthulhu_ 4y ago
Isn't lisp a scripting language though? Different flavor of language. I mean JS used to be a scripting language, but thanks to Reasons there's a lot more involved to get fast development cycles.
- lisper 4y ago
  > Isn't lisp a scripting language though? No. Where did you get that idea?

markhelo 4y ago

"Microsoft has been killing it over the last decade regarding dev tooling and experience, so it is not a big surprise." To be fair, for all the flack Microsoft got/gets, the dev tooling for Windows ecosystem is miles ahead of anyone else and world class. Perhaps I am biased as I worked there at one point, but since I don't anymore, I have also seen tooling from Apple and Google and they are a couple of decades behind. There is some truth to why Steve Ballmer went ballistic with his Developer chant, they really built great tooling for developers.

deleted 4y ago
[deleted]
game-of-throws 4y ago
MS had "edit and continue" (aka hot reloading) in Visual Basic in the 90s. Then I switched to other languages and I've gone without it the rest of my career. I don't think VB the language is very good, but the developer experience still beats anything I've used since then.
pjmlp 4y ago
With the caveat that Borland is even better before they decided to focus on enterprise customers, and went through all those acquisitions and name changes. Delphi and C++ Builder are still unmatched in many capabilities on the Visual Studio side.
refulgentis 4y ago
This is an odd response given the article calls at Google as having the gold standard for this, and I'm not sure there's any equivalent at all at MS? They push Flutter too
- jayd16 4y ago
  You mean like this? https://docs.microsoft.com/en-us/visualstudio/debugger/hot-reload?view=vs-2022 https://docs.microsoft.com/en-us/visualstudio/debugger/hot-r... "Microsoft has been killing it over the last decade regarding dev tooling and experience" was a direct quote from the article.
  - refulgentis 4y ago
    Thank you! That context makes it much clearer
- m_at_goog 4y ago
  Maybe they mean internal at Google? Internal Google tooling is pretty hit or miss, especially with older products that are a patch work of different internal only Google stacks.
- pjmlp 4y ago
  The gold standard are Smalltalk and Common Lisp environments, that people pushing Flutter tend to ignore on their marketing, as they ignored the existing work on Java and .NET ecosystems.
tester756 4y ago
There's emoji after "killing it" I believe it changes meaning of this sentence.
- frosted-flakes 4y ago
  No it doesn't? In that context, "killing it" means doing a great job.
can16358p 4y ago
Agreed. Visual Studio is an excellent piece of software, along with .NET and C#. I think Apple isn't that bad either, yet still behind MS. Google is a disaster though. A few weeks ago I needed to download Android Studio. Downloaded a clean stable release from its official site for my machine (M1 Mac). From that clean install literally erroring while trying to launch AVDs to cryptic error messages about JDK environments, Google's the only IDE out of these big three where I get countless of errors and losing hours on something that literally doesn't work out of the box. Hope Xcode and VS never becomes something crappy like Android Studio.

musesum 4y ago

Ironically, I think Brad Cox had something like this in mind, after coming up with Objective C. Or at least, pluggable components [1] I wonder what the threat model would be? Injectable binaries seem like a decent attack vector. But, if we're talking 2040, maybe a signable Merkle tree would do the trick. Meanwhile, have been experimenting with recompiling Metal code at runtime. Was kinda fun with ObjC/C++/OpenGL, a few years ago. [1] https://thenewstack.io/objective-cs-roots-in-the-life-of-brad-cox/ https://thenewstack.io/objective-cs-roots-in-the-life-of-bra...

dmix 4y ago
Erlang has had hotloading for a long time and seems to be fine security wise AFAIK.
- kaba0 4y ago
  Hot reloading’s quality (and to a degree, security) depends mostly on how fine-grained a change can be. The reason Lisp-REPl workloads are so well loved is that very small scopes can be changed easily, Erlang also has a sane encapsulation that can be swapped without much fuss.
  - jjtheblunt 4y ago
    just wanted to say i really like the clarity of that explanation
- melony 4y ago
  Most of (traditional) Erlang deploymens are in embedded systems. They have a different threat model.
- toast0 4y ago
  Erlang has a very limited security model. In the default distribution, any process on any node can spawn a process on any other connected node to run any function --- you can send the function too. Modules can have a function to run on load, too. Loading an untrusted module is asking for that module to take over your whole system. Best to make sure nobody unauthorized can do that.

leecommamichael 4y ago

You can hot-reload any language that can load a dynamic library. Compile the hot-reloadable portion of your app to a dylib and use a hotkey to reload the lib.

mananaysiempre 4y ago
That is only the beginning, isn’t it? The hard part is figuring out how to migrate state, and clearly saying “no” when that fails instead of leaving the user to debug a configuration that could not have arisen had the new code been started from a clean slate. (I don’t think that’s actually possible to disprove, even, but at the very least guaranteeing that memory contains the types the new code thinks it does would be good.)