8 ms·

Cheerp – A C/C++ compiler for web applications

59 points by multimillion 12y ago

Kip9000 12y ago
I wonder what advantages choosing C++ to write web apps would bring. At the end of the day it's all JavaScript so performance is rather moot point.
- virmundi 12y ago
  Probably none. However, it could act as a gateway drug for C++ desktop folk. They do exist.
  - tylermac1 12y ago
    We do exist. The fables are true.
- recentdarkness 12y ago
  So it's like GWT for C++
- Touche 12y ago
  That's actually not true. Emscripten compiles to code that is much faster than hand-written JavaScript. In this case they are not using Emscripten or a similar technique but are compiling to regular old JavaScript, so performance probably is the same, rather this might be for people who just like C++, like what GWT is for Java devs.
  - aikah 12y ago
    While true,if your "c++" hit the DOM , in the client, you'll have the same problems as hand-written JS.
  - Kip9000 12y ago
    You misunderstood. People mostly write with C++ when performance is critical. Why? C++ offers deterministic memory management, Specialize to CPU instruction set and better use of CPU caches etc. Those performance benefits would not translate when you cross compile to something like JavaScript. I get the point about converting the legacy desktop apps to web apps, but how would it handle the architectural differences ( Desktop apps don't scale)
    - humanrebar 12y ago
      > People mostly write with C++ when performance is critical. Performance is a big reason people use C++, but there are many others. For example, people also write C++ when correctness is critical (bank software, safety-critical systems, etc.).
      - pkolaczk 12y ago
        Writing for correctness in a language with no memory-safety, weak type system and, till not very long ago, no standardized memory-model, and UB in every other paragraph of the specs? Good joke. If they are really doing this, they have no idea what they are doing. There are plenty of languages better for safety-critical systems than C++; even widely hated, boring Java is much better.
        Kip9000 12y ago
        That was going to be my response..
        pkolaczk 12y ago
        I was replying to the statement: "For example, people also write C++ when correctness is critical". And I say if someone writes C++ in a correctness critical system, he must not know what he is doing. Even if you're using only STL, RAII and following all the good coding practices, there are still so many ways to screw things up, that C++ is among the worst choices in this regard.
- humanrebar 12y ago
  > At the end of the day it's all JavaScript so performance is rather moot point That's probably true, but C++ does provide very powerful compile-time evaluation mechanisms like templates, constexpr (compile-time evaluated constants and functions), and template metaprogramming. That being said, compile-time C++ can look very gross since most of the features are accidental. However, there are a lot of huge performance benefits to moving computation to compile time: selecting the most optimal algorithm for a type, guaranteeing you don't mismatch your units, precompiling search (glob, regex) engines, eliminating dead code, and so on. So I would be shocked if at least some javascript applications couldn't be much faster and more correct by writing in C++ first and compiling to js. That being said, it's probably not in scope for a minimum-viable product, so improving already business-critical parts of the code base might be the best place to start.
  - pkolaczk 12y ago
    Metaprogramming and type-safety facilities of C++ are very limited compared to other languages like Haskell or Scala. And for the latter there is a JS compiler as well.
- swah 12y ago
  > it's all JavaScript so performance is rather moot point If that was the case, http://asmjs.org/ http://asmjs.org/ wouldn't be a thing.
  - oso2k 12y ago
    According to the Chrome guys...it isn't a thing [0][1], and I tend to agree. They've kept up, and often exceeded FF, IMO, for real code by making a better JIT compiler. They still haven't implemented asm.js and yet their "naive" approach to asm.js style code is on par. [0] https://code.google.com/p/v8/issues/detail?id=2599#c53 https://code.google.com/p/v8/issues/detail?id=2599#c53 [1] http://mrale.ph/blog/2013/03/28/why-asmjs-bothers-me.html http://mrale.ph/blog/2013/03/28/why-asmjs-bothers-me.html
    - gcp 12y ago
      The links you pasted show Firefox currently being 3x faster than Chrome when running asm.js code, so I'm not sure what your point is. V8 is good at generating fast code without the hints, but obviously the extra restrictions help the optimizer. Even Google admits this when they try to promote Dart. asm.js does little for you if you write "real JS", but this thread is about cross-compiling other languages, which clearly has real world use.
    - swah 12y ago
      I'm not a compiler expert but I also have the feeling that a new bytecode would be better. But if I recall correctly, there are very good reasons why we don't have that in our browsers; security concerns maybe? Anyone? Or http://hn.algolia.com http://hn.algolia.com, here I go again! (What a great post, thanks for linking. Even though I follow mraleph on twitter, I had never opened his website. Probably because it all looks like scary compiler stuff.)
- aboodman 12y ago
  Another major benefit (of emscripten too) is that is you have significant non-presentation client-side logic, it can be shared between iOS, Android, and the Web. For example take something like Dropbox's Carousel architecture, which shares the client side cache, date model, and sync client between iOS and Android via a C++ library. Something like Cheerp or Emscripten allows you to also use this same library on the web.
- flohofwoe 12y ago
  For me it's portability first, decent performance second and third the 'seamless distribution model' of the web (no installation, no app shops, no code signing, just an URL). I wouldn't write a web-only app in C++, but if the same code needs to run on other platforms as well (e.g. native mobile, desktop or gaming consoles) then C/C++ is basically the only choice. Also, at least in emscripten, compiled code is faster then hand-written JS for several reasons (asm.js, LLVM optimizer passes, no gc), so it makes sense to write stuff like physics/pathfinding/AI engines in C/C++ and compile it to JS. Plus, it's fun to write a desktop OpenGL demo, flip a build system switch and run it in the browser ;)
pierre-renaux 12y ago
If anyone from Cheerp reads this, I use emscripten (https://github.com/kripken/emscripten https://github.com/kripken/emscripten) at the moment, is Cheerp any better ? Specifically does it compile faster, generates a smaller final .js output, or produce "faster" code ?
- kolodny 12y ago
  I just ran the HelloClient.cpp from their example page [1] and the compiled file was 1.7 Mb [1] http://www.leaningtech.com/cheerp/examples/ http://www.leaningtech.com/cheerp/examples/
  - mx267 12y ago
    Even if js files are usually delivered compressd by gzip (which is very effective on unminimized js files), we are aware of the issue and we are working on reducing output size. An integrated code minimizer is in the pipeline for release 1.1, and for the medium term we are working on an optimizer which cuts away unneeded libc++ initialization, which is preventing the dead code eliminator from pruning the non-useful libc++ code (which is a great part of that 1.7Mb). So, expect big improvements in this area! Disclaimer: I am one of Leaning Technologies founders.
- flohofwoe 12y ago
  I'm not from Cheerp, but it looks like the main difference is this (taken from their front page): Dynamic memory management. C++ objects are translated directly to JS objects, without the proxy of an emulated, flat memory space. Allow your applications to exploit the JavaScript VM garbage collector and co-exist with fair, on-demand memory allocation. I don't think that's a good thing though, since the reason why emscripten compiled code is fast is because it has a flat memory space and doesn't create expensive JS objects. Only advantage IMHO is that you don't need to allocate a big chunk of memory ahead of time (although I think emscripten still allows a growable heap as an option, but with a performance penalty).
- dochtman 12y ago
  The Emscripten author wrote a blog post when Cheerp (then called duetto) was first announced: http://mozakai.blogspot.co.uk/2013/11/c-to-javascript-emscripten-mandreel-and.html http://mozakai.blogspot.co.uk/2013/11/c-to-javascript-emscri...
neuromancer2701 12y ago
From my understanding it also allows you to write your front and back end in one application and language. Then it compiles the front end to JS and the backend to C++ executable. I think this is where a large advantage can be seen. edit: it automates the connection between the front and backends tying the two together.
jbarrow 12y ago
This is somewhat off-topic but they turned user-scalability off, making it impossible to zoom out (of the pre-zoomed in) mobile site. Other than that, it's an interesting proposition and I look forward to trying it out.
- mx267 12y ago
  Thanks for the report, we have fixed that issue today.
deleted 12y ago
[deleted]
_kst_ 12y ago
I know C and C++ pretty well; I wonder what this "C/C++" language is like.
- pmelendez 12y ago
  The subset that is the interception of both? which would be a subset of C. (Although I am pretty sure that wasn't what the author had in mind)
  - oso2k 12y ago
    Bjarne has always maintained that C++ is (mostly) backwards compatible with C. And that's what most people mean by C/C++.
    - _kst_ 12y ago
      I know that C++ is mostly, but not entirely, backwards compatible with C. That doesn't answer the question of what "C/C++" means. They're two different languages. The problem is that different people mean different things by "C/C++". Some people mean "C and C++"; others just seem to be unaware that they're distinct.
      - multimillion 12y ago
        Cheerp, like clang (upon which it is based), can compile both C and C++ files.
- deleted 12y ago
  [deleted]
- mx267 12y ago
  Cheerp, like clang (upon which it is based), can compile both C and C++ code.
keithnoizu 12y ago
Interesting although if you want massive performance on a web application i'd probably vie for erlang unless you're doing something computationally complex on the backend. It would be nice to be able to write code once and use in multiple places but theres often so much extra work involved in that, that for many applications it makes more sense to just use interfaces etc. Neat project either way.
- farresito 12y ago
  If you want massive performance, you most likely want to avoid erlang; if you want massive scalability, erlang might very well be a great fit. I think it's quite different.
  - keithnoizu 12y ago
    Performance in terms of request throughput you can serve per minute for some given set of CPU and RAM. Erlang processing is slower than C by quite a bit but the reduced threading costs tends to make up for it when you are in a scenario where you need to serve multiple requests simultaneously. On an apples to apples comparison well written C is going to beat erlang on this every time but once you start getting into threading, mutex locks etc. the equation starts to shift more towards Erlang favor _as long_ as each request you are serving is not highly computational in nature and would involve semaphores, and so on for thread management in c.
adamnemecek 12y ago
Reminds me of Wt http://www.webtoolkit.eu/wt http://www.webtoolkit.eu/wt
ksikka 12y ago
"Cheerp compiles to native binary code backend, JavaScript frontend, and automatically generates RPC communication code" The RPC feature sounds like it could be immensely useful for day-to-day web development. But the C/C++ is a deal-breaker for most web developers. Are there any projects that only do the RPC autogeneration stuff? Also can frontend/backend code be shared (if there are no dependencies to the browser/unix system)?
- mx267 12y ago
  Yes, code without client- or server-specific dependencies can be shared.
shmerl 12y ago
A different idea, but still an interesting C++ Web development framework: http://cppcms.com http://cppcms.com
azakai 12y ago
I'm a bit puzzled by the rebranding. First of all, the logo and the name sound a bit similar to Twitter. And I'm not sure what bird noises have to do with a compiler? The previous name, Duetto, made sense to me, since they compile to both client and server, so it's like two things running in harmony, which is a duet in music.

59 points by multimillion 12y ago

I wonder what advantages choosing C++ to write web apps would bring. At the end of the day it's all JavaScript so performance is rather moot point.

virmundi 12y ago
Probably none. However, it could act as a gateway drug for C++ desktop folk. They do exist.
- tylermac1 12y ago
  We do exist. The fables are true.
recentdarkness 12y ago
So it's like GWT for C++
Touche 12y ago
That's actually not true. Emscripten compiles to code that is much faster than hand-written JavaScript. In this case they are not using Emscripten or a similar technique but are compiling to regular old JavaScript, so performance probably is the same, rather this might be for people who just like C++, like what GWT is for Java devs.
- aikah 12y ago
  While true,if your "c++" hit the DOM , in the client, you'll have the same problems as hand-written JS.
- Kip9000 12y ago
  You misunderstood. People mostly write with C++ when performance is critical. Why? C++ offers deterministic memory management, Specialize to CPU instruction set and better use of CPU caches etc. Those performance benefits would not translate when you cross compile to something like JavaScript. I get the point about converting the legacy desktop apps to web apps, but how would it handle the architectural differences ( Desktop apps don't scale)
  - humanrebar 12y ago
    > People mostly write with C++ when performance is critical. Performance is a big reason people use C++, but there are many others. For example, people also write C++ when correctness is critical (bank software, safety-critical systems, etc.).
    - pkolaczk 12y ago
      Writing for correctness in a language with no memory-safety, weak type system and, till not very long ago, no standardized memory-model, and UB in every other paragraph of the specs? Good joke. If they are really doing this, they have no idea what they are doing. There are plenty of languages better for safety-critical systems than C++; even widely hated, boring Java is much better.
      - Kip9000 12y ago
        That was going to be my response..
        pkolaczk 12y ago
        I was replying to the statement: "For example, people also write C++ when correctness is critical". And I say if someone writes C++ in a correctness critical system, he must not know what he is doing. Even if you're using only STL, RAII and following all the good coding practices, there are still so many ways to screw things up, that C++ is among the worst choices in this regard.
humanrebar 12y ago
> At the end of the day it's all JavaScript so performance is rather moot point That's probably true, but C++ does provide very powerful compile-time evaluation mechanisms like templates, constexpr (compile-time evaluated constants and functions), and template metaprogramming. That being said, compile-time C++ can look very gross since most of the features are accidental. However, there are a lot of huge performance benefits to moving computation to compile time: selecting the most optimal algorithm for a type, guaranteeing you don't mismatch your units, precompiling search (glob, regex) engines, eliminating dead code, and so on. So I would be shocked if at least some javascript applications couldn't be much faster and more correct by writing in C++ first and compiling to js. That being said, it's probably not in scope for a minimum-viable product, so improving already business-critical parts of the code base might be the best place to start.
- pkolaczk 12y ago
  Metaprogramming and type-safety facilities of C++ are very limited compared to other languages like Haskell or Scala. And for the latter there is a JS compiler as well.
swah 12y ago
> it's all JavaScript so performance is rather moot point If that was the case, http://asmjs.org/ http://asmjs.org/ wouldn't be a thing.
- oso2k 12y ago
  According to the Chrome guys...it isn't a thing [0][1], and I tend to agree. They've kept up, and often exceeded FF, IMO, for real code by making a better JIT compiler. They still haven't implemented asm.js and yet their "naive" approach to asm.js style code is on par. [0] https://code.google.com/p/v8/issues/detail?id=2599#c53 https://code.google.com/p/v8/issues/detail?id=2599#c53 [1] http://mrale.ph/blog/2013/03/28/why-asmjs-bothers-me.html http://mrale.ph/blog/2013/03/28/why-asmjs-bothers-me.html
  - gcp 12y ago
    The links you pasted show Firefox currently being 3x faster than Chrome when running asm.js code, so I'm not sure what your point is. V8 is good at generating fast code without the hints, but obviously the extra restrictions help the optimizer. Even Google admits this when they try to promote Dart. asm.js does little for you if you write "real JS", but this thread is about cross-compiling other languages, which clearly has real world use.
  - swah 12y ago
    I'm not a compiler expert but I also have the feeling that a new bytecode would be better. But if I recall correctly, there are very good reasons why we don't have that in our browsers; security concerns maybe? Anyone? Or http://hn.algolia.com http://hn.algolia.com, here I go again! (What a great post, thanks for linking. Even though I follow mraleph on twitter, I had never opened his website. Probably because it all looks like scary compiler stuff.)
aboodman 12y ago
Another major benefit (of emscripten too) is that is you have significant non-presentation client-side logic, it can be shared between iOS, Android, and the Web. For example take something like Dropbox's Carousel architecture, which shares the client side cache, date model, and sync client between iOS and Android via a C++ library. Something like Cheerp or Emscripten allows you to also use this same library on the web.
flohofwoe 12y ago
For me it's portability first, decent performance second and third the 'seamless distribution model' of the web (no installation, no app shops, no code signing, just an URL). I wouldn't write a web-only app in C++, but if the same code needs to run on other platforms as well (e.g. native mobile, desktop or gaming consoles) then C/C++ is basically the only choice. Also, at least in emscripten, compiled code is faster then hand-written JS for several reasons (asm.js, LLVM optimizer passes, no gc), so it makes sense to write stuff like physics/pathfinding/AI engines in C/C++ and compile it to JS. Plus, it's fun to write a desktop OpenGL demo, flip a build system switch and run it in the browser ;)

pierre-renaux 12y ago

If anyone from Cheerp reads this, I use emscripten (https://github.com/kripken/emscripten https://github.com/kripken/emscripten) at the moment, is Cheerp any better ? Specifically does it compile faster, generates a smaller final .js output, or produce "faster" code ?

kolodny 12y ago
I just ran the HelloClient.cpp from their example page [1] and the compiled file was 1.7 Mb [1] http://www.leaningtech.com/cheerp/examples/ http://www.leaningtech.com/cheerp/examples/
- mx267 12y ago
  Even if js files are usually delivered compressd by gzip (which is very effective on unminimized js files), we are aware of the issue and we are working on reducing output size. An integrated code minimizer is in the pipeline for release 1.1, and for the medium term we are working on an optimizer which cuts away unneeded libc++ initialization, which is preventing the dead code eliminator from pruning the non-useful libc++ code (which is a great part of that 1.7Mb). So, expect big improvements in this area! Disclaimer: I am one of Leaning Technologies founders.
flohofwoe 12y ago
I'm not from Cheerp, but it looks like the main difference is this (taken from their front page): Dynamic memory management. C++ objects are translated directly to JS objects, without the proxy of an emulated, flat memory space. Allow your applications to exploit the JavaScript VM garbage collector and co-exist with fair, on-demand memory allocation. I don't think that's a good thing though, since the reason why emscripten compiled code is fast is because it has a flat memory space and doesn't create expensive JS objects. Only advantage IMHO is that you don't need to allocate a big chunk of memory ahead of time (although I think emscripten still allows a growable heap as an option, but with a performance penalty).
dochtman 12y ago
The Emscripten author wrote a blog post when Cheerp (then called duetto) was first announced: http://mozakai.blogspot.co.uk/2013/11/c-to-javascript-emscripten-mandreel-and.html http://mozakai.blogspot.co.uk/2013/11/c-to-javascript-emscri...

neuromancer2701 12y ago

From my understanding it also allows you to write your front and back end in one application and language. Then it compiles the front end to JS and the backend to C++ executable. I think this is where a large advantage can be seen. edit: it automates the connection between the front and backends tying the two together.

jbarrow 12y ago

This is somewhat off-topic but they turned user-scalability off, making it impossible to zoom out (of the pre-zoomed in) mobile site. Other than that, it's an interesting proposition and I look forward to trying it out.

mx267 12y ago
Thanks for the report, we have fixed that issue today.

deleted 12y ago

[deleted]

_kst_ 12y ago

I know C and C++ pretty well; I wonder what this "C/C++" language is like.

pmelendez 12y ago
The subset that is the interception of both? which would be a subset of C. (Although I am pretty sure that wasn't what the author had in mind)
- oso2k 12y ago
  Bjarne has always maintained that C++ is (mostly) backwards compatible with C. And that's what most people mean by C/C++.
  - _kst_ 12y ago
    I know that C++ is mostly, but not entirely, backwards compatible with C. That doesn't answer the question of what "C/C++" means. They're two different languages. The problem is that different people mean different things by "C/C++". Some people mean "C and C++"; others just seem to be unaware that they're distinct.
    - multimillion 12y ago
      Cheerp, like clang (upon which it is based), can compile both C and C++ files.
deleted 12y ago
[deleted]
mx267 12y ago
Cheerp, like clang (upon which it is based), can compile both C and C++ code.

keithnoizu 12y ago

Interesting although if you want massive performance on a web application i'd probably vie for erlang unless you're doing something computationally complex on the backend. It would be nice to be able to write code once and use in multiple places but theres often so much extra work involved in that, that for many applications it makes more sense to just use interfaces etc. Neat project either way.

farresito 12y ago
If you want massive performance, you most likely want to avoid erlang; if you want massive scalability, erlang might very well be a great fit. I think it's quite different.
- keithnoizu 12y ago
  Performance in terms of request throughput you can serve per minute for some given set of CPU and RAM. Erlang processing is slower than C by quite a bit but the reduced threading costs tends to make up for it when you are in a scenario where you need to serve multiple requests simultaneously. On an apples to apples comparison well written C is going to beat erlang on this every time but once you start getting into threading, mutex locks etc. the equation starts to shift more towards Erlang favor _as long_ as each request you are serving is not highly computational in nature and would involve semaphores, and so on for thread management in c.

adamnemecek 12y ago

Reminds me of Wt http://www.webtoolkit.eu/wt http://www.webtoolkit.eu/wt

ksikka 12y ago

"Cheerp compiles to native binary code backend, JavaScript frontend, and automatically generates RPC communication code" The RPC feature sounds like it could be immensely useful for day-to-day web development. But the C/C++ is a deal-breaker for most web developers. Are there any projects that only do the RPC autogeneration stuff? Also can frontend/backend code be shared (if there are no dependencies to the browser/unix system)?

mx267 12y ago
Yes, code without client- or server-specific dependencies can be shared.

shmerl 12y ago

A different idea, but still an interesting C++ Web development framework: http://cppcms.com http://cppcms.com

azakai 12y ago

I'm a bit puzzled by the rebranding. First of all, the logo and the name sound a bit similar to Twitter. And I'm not sure what bird noises have to do with a compiler? The previous name, Duetto, made sense to me, since they compile to both client and server, so it's like two things running in harmony, which is a duet in music.