Could anyone explain to me what the difference with normal ruby is?
"Lightweight", does that mean:
Small but slow?
Big but fast?
Quite small and quite fast, but with a half-assed library?
Big, slow, but low RAM usage?
I understand from another comment that this is intended for embedded systems. Does that mean running it on a microcontroller without OS? Cause the moment you can flash Linux, you can use Ruby MRI, no?
>I understand from another comment that this is intended for embedded systems.
Nope, he said embedding. He means things like Lua where you have a scripting language embedded in a program that is running on a faster lnaguage. Common in video game dev.
>Does that mean running it on a microcontroller without OS?
Nope, not necessarily. It being portable means it's plausible but it's an unlikely usage scenario. More likely, it means being able to use it across a variety of POSIX derivatives.
>Cause the moment you can flash Linux, you can use Ruby MRI, no?
Also not true. What a micro-distribution of Linux can run on is not necessarily something MRI Ruby can also run on.
Heavy Ruby is not designed for speed, and much of its heaviness causes slowness. It's entirely possible/likely that mruby will be in the same ballpark as luajit2 soon after release.
I've been waiting this for a long time. There's also TinyRB (http://code.macournoyer.com/tinyrb/) but it's too small subset of ruby to be useful and seems abandoned.
But my first impressions are not very positive (stripped x86_64 executables with -Os):
-rwxr-xr-x 1 user group 708480 Apr 20 11:27 mrbc
-rwxr-xr-x 1 user group 713056 Apr 20 11:27 mruby
-rwxr-xr-x 1 user group 712128 Apr 20 11:27 mrubysample
compared to lua-5.2.0:
-rwxr-xr-x 1 user group 147864 Apr 20 11:28 lua
-rwxr-xr-x 1 user group 99168 Apr 20 11:28 luac
I'm not a big fan of lua as a language but it has been the only option to do scripting on small embedded systems. I've manged to compile size-optimized version of lua on arm to the size of about 80kb but mruby just might be too big for my embedded usage.
Honestly, I'm pretty impressed it's only 7-10 times the size. Ruby is a comparatively huge language, and the compiled size will more likely get smaller than larger from here.
- comments start with --
- no bitwise operations in language
- default numeric data type is floating-point. it's possible to change it to
integer but it raises uncertainty with compatibility of external libraries
- OOP in lua is quite programmer-specific: everyone seems to have their own
best practises
Of course lua has good features too, like coroutines and good C API. Squirrel (http://squirrel-lang.org/) also seems like a nicer alternative to lua but it requires a C++ compiler.
IMHO lua's best asset is the small and fast VM. I wish there would be other good, modern languages that target it.
for bitwise ops: look at 5.2, it has it now. 32-bit operations.
floating point arithmetic: in practice, I haven't seen it as a problem as soon as I stay within the 32-bit range - then the numbers can be represented exactly, so the abstraction works well.
OOP: can't say for it, I did not do it much.
For the "fast" - check luajit (http://luajit.org/) - it is near-native speed while remaining reasonably slow.
The annoyance that I'd thought of is that the array indexing starts with one, not zero - this brings some headaches during the index calculations. But this also forces to rethink the logic to use more of iterators, and abstract away from the indices. So, after all, it is not that big of a deal.
Oh on arm you will definitely will want to check out luajit precisely for the number performance - see this comment for details : http://news.ycombinator.com/item?id=2617835 - luajit will use integers where it can.
I did not experiment with this myself though, but hopefully it might ease your woes with no FPU - http://luajit.org/performance_arm.html shows 85x speedup for md5, which I suppose would be integer algorithm.
Out of curiosity, what is the platform, if not a secret ?
-- Comment syntax is that a big deal?
- bit wise: LuaJIT?
- Just like in Python and Javascript, what's the issue?
Doubles do just fine as integers if you code so that
you always wind up with other integers.
- OOP - This I agree is a community fragmentation issue.
One issue is that it's easy to end up with things that aren't round numbers by mistake (if you do any sort of division, for example, or are getting results from an external library, etc., and strategies for reducing errors that rely on the programmer not screwing up are generally doomed to failure.) That has several problems: floats are imprecise, you introduce the potential for additional runtime errors if you're doing something like indexing into an array, etc.
Also, Python has separate integer and floating-point operations:
The GP mentioned arbitrary precision integers, which Python has. I believe they're called Long, and integers that overflow are cast to Long (represented as 123L).
Agree strongly about the floating point being a problem. I much prefer languages like Erlang, Python, and Ruby where the default numeric type is arbitrary precision integers.
I see, thank you. None of this sounds like a show-stopper to me, but it's good to have a more complete view of a language I'm not intimately familiar with.
Yes, none are show stoppers. Lua suits perfectly for for the use it was designed: small embeddable scripting. I hope no one is writing millions of lines of lua code! For me even small amount just does not "feel right" the way for example ruby does. That's why I've been eagerly waiting for mruby but unfortunately it does not (yet) fill the void.
I am seeing this sort of thing frequently in GitHub - people start working on something and it gets "released" before they are ready with it and the authors have to scramble to say that this is not ready, ward off degrading comments etc.
The js.js blog post mentions this and in mrbuy , the README has just been updated. Is social coding being taken to the extreme?
I seriously doubt that whether the repositories were private was a financial consideration. More likely, they wanted others to be able to find the project and join in.
People who develop software of this caliber can easily afford the expense of a private Github repository if they want one.
>mRuby is the light-weighted implementation of ruby language complied with ISO
standard to execute various environment. It can run as 'interpreter form' or
'compile and execute on vm form' according to its module construction.
Can anyone tell me how it's different from other ruby implementations? What does 'execute various environment' mean? Can I run it inside JVM like JRuby?
Is RiteVM related? The reddit faq mentions both embedded systems and embedding via C API, I don't know which is the goal of that project. (sorry if that was covered in the talk, I'd rather not watch youtube right now)
Depends on the audience. There are probably lots of people who know Ruby and would like to be able to use it where they currently can't. It might not be likely to win the hearts of the C++ game engine hackers, but that might not necessarily be the goal.
It's not elegant but it's incredibly compact and isolated. I embedded it as a language in an iPhone game (as have many others). Making it bridge with Objective-C was fairly straight-forward and the memory/speed footprint was acceptable for a mobile device.
It's like JavaScript with different warts. Examples: Bad at Unicode, arrays start at 1, regexps is a second-class citizen, weird OO, arrays are implemented as hash tables (like PHP), hash tables are weird, no int type, Java-like inflexibility wrt extensibility (no generalization for iteration, for example) etc.
I've only dabbled a bit in Lua but I mostly read very positive things about it and there are tons of success stories of embedded Lua out there. Way more than any other embedded scripting language. Unlike Ruby or Python etc Lua was designed from the ground up for this.
As others have said, it is small, fast and flexible with a very permissive licence so it is the scripting language of choice for embedded and gaming applications.
"Lightweight", does that mean:
I understand from another comment that this is intended for embedded systems. Does that mean running it on a microcontroller without OS? Cause the moment you can flash Linux, you can use Ruby MRI, no?