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I have no idea why people keep suggesting this. There isn't a single precedent for a "universal IL" that isn't somehow tightly bound to one implied runtime mode

I have no idea why people keep suggesting this. There isn't a single precedent for a "universal IL" that isn't somehow tightly bound to one implied runtime model, type system, etc., and yet people keep calling for something like this for the web. Look at the "bag on the side" that is the DLR, look at the attempts at making Jython run quickly, look at the failed attempts over the years at providing a common IL for UNIX (e.g. start reading here: http://en.wikipedia.org/wiki/Ten15 http://en.wikipedia.org/wiki/Ten15), look at the resounding failure of Parrot to become a universal VM, look at the recent rebuttals at attempts to use LLVM as an architecture-independent format. What benefit do you expect your "machine code" to have over JavaScript?

sambeau 15y ago
What benefit do you expect your "machine code" to have over JavaScript? All the benefits that people proposing new web languages would impart. There are a good reasons why Google are proposing running Dart straight on their VM in Chrome. It will be faster, safer, easier to jit, easier to prove correct etc. Having a firm foundation would make it easier to innovate. Companies could still be encouraged to compete for faster and safer implementations. The failure of Parrot to catch on has very little to do with the technology, nor the proposition of a general-purpose dynamic language VM. Parrot was simply in the wrong place at the wrong time (and it took too long to deliver). It also made the mistake of tying itself to an unfinished language spec. If they had concentrated on making a VM that could run Python, Ruby and Javascript they would have been in the right place at the right time when Perl 6 was finally ready to be implemented. People are beginning to use Javascript and the V8 engine in a manner similar to the original Parrot proposal. The time is right for a general-purpose IL so we can compile Coffeescript straight to the Javascript VM. LLVM is being questioned by some because a) it isn't a VM it's just an IL so it is a compiler technology not a VM tech b) it is too low level to make the jitting of dynamic languages suitably efficient. LLVM is too low-level; Javascript is too high (and opinionated). Judging innovation by precedence is always a bad idea.
overgard 15y ago
I agree with most of what you're saying, but I think an indirect counter-example is C. It's not technically a universal intermediate language, but it's widely considered to be a "portable assembly language"; which many vastly more dynamic languages compile down to. I think the web could use it's own version of something like C -- that is, a low level, no-frills language that maps closer to how hardware works. I imagine for this web version of C -- and it should be a language, not a byte code format -- it would need to satisfy these properties: - language constructs that map semi obviously to machine instructions (ie, you don't need to spend a lot of time guessing what "switch" or "while" or "struct" get turned into), while avoiding things that might not be so obvious. (What does a closure look like in assembly? Or a generator?) - types that correspond to machine types - some sort of predictable and low level memory model (without pointers, but with some sort of way to avoid garbage collection issues. Maybe something with reference counting)
- tomp 15y ago
  You're assuming that all code found on the web is well-written, without bugs and with no malicious intents. Both Java and CLR bytecodes are designed specifically in a way so that they are verifiable, so that the compiler can be sure that the code doesn't do anything it's not supposed to do (e.g. access IO functions, write to unallocated memory, spawn new threads, ...). Also, a browser has to be able to ensure that untrusted code can only use a limited amount of resources, that is why we have garbage collection, and VMs (interpreted/JIT compiled code can be controlled and interrupted more easily than native code). Higher level constructs carry more semantics, that is why they are easier to verify/sandbox.
  - overgard 15y ago
    I am assuming no such thing, that's why I suggested pointers and such should be left out. I'm not actually literally suggesting that we put C in a browser, I'm using it as a design metaphor. You can do fast and low level without C style pointers (for example, fortran* .. not that I'm advocating fortran either ) Sidenote: GC wouldn't prevent anyone from stealing a lot of resources. Either way you can ask for a lot of resources and not give them back. * Yes I know fortran has a thing called a pointer, but it's a lot different.

sambeau 15y ago

What benefit do you expect your "machine code" to have over JavaScript? All the benefits that people proposing new web languages would impart. There are a good reasons why Google are proposing running Dart straight on their VM in Chrome. It will be faster, safer, easier to jit, easier to prove correct etc. Having a firm foundation would make it easier to innovate. Companies could still be encouraged to compete for faster and safer implementations. The failure of Parrot to catch on has very little to do with the technology, nor the proposition of a general-purpose dynamic language VM. Parrot was simply in the wrong place at the wrong time (and it took too long to deliver). It also made the mistake of tying itself to an unfinished language spec. If they had concentrated on making a VM that could run Python, Ruby and Javascript they would have been in the right place at the right time when Perl 6 was finally ready to be implemented. People are beginning to use Javascript and the V8 engine in a manner similar to the original Parrot proposal. The time is right for a general-purpose IL so we can compile Coffeescript straight to the Javascript VM. LLVM is being questioned by some because a) it isn't a VM it's just an IL so it is a compiler technology not a VM tech b) it is too low level to make the jitting of dynamic languages suitably efficient. LLVM is too low-level; Javascript is too high (and opinionated). Judging innovation by precedence is always a bad idea.

overgard 15y ago

I agree with most of what you're saying, but I think an indirect counter-example is C. It's not technically a universal intermediate language, but it's widely considered to be a "portable assembly language"; which many vastly more dynamic languages compile down to. I think the web could use it's own version of something like C -- that is, a low level, no-frills language that maps closer to how hardware works. I imagine for this web version of C -- and it should be a language, not a byte code format -- it would need to satisfy these properties: - language constructs that map semi obviously to machine instructions (ie, you don't need to spend a lot of time guessing what "switch" or "while" or "struct" get turned into), while avoiding things that might not be so obvious. (What does a closure look like in assembly? Or a generator?) - types that correspond to machine types - some sort of predictable and low level memory model (without pointers, but with some sort of way to avoid garbage collection issues. Maybe something with reference counting)

tomp 15y ago
You're assuming that all code found on the web is well-written, without bugs and with no malicious intents. Both Java and CLR bytecodes are designed specifically in a way so that they are verifiable, so that the compiler can be sure that the code doesn't do anything it's not supposed to do (e.g. access IO functions, write to unallocated memory, spawn new threads, ...). Also, a browser has to be able to ensure that untrusted code can only use a limited amount of resources, that is why we have garbage collection, and VMs (interpreted/JIT compiled code can be controlled and interrupted more easily than native code). Higher level constructs carry more semantics, that is why they are easier to verify/sandbox.
- overgard 15y ago
  I am assuming no such thing, that's why I suggested pointers and such should be left out. I'm not actually literally suggesting that we put C in a browser, I'm using it as a design metaphor. You can do fast and low level without C style pointers (for example, fortran* .. not that I'm advocating fortran either ) Sidenote: GC wouldn't prevent anyone from stealing a lot of resources. Either way you can ask for a lot of resources and not give them back. * Yes I know fortran has a thing called a pointer, but it's a lot different.