# How much of the rubyspec does hotruby implement?

**URL:** <https://www.ruby-forum.com/t/how-much-of-the-rubyspec-does-hotruby-implement/191932>\
**Category:** Ruby\
**Created:** [July 20, 2010, 10:39pm UTC](https://www.ruby-forum.com/t/how-much-of-the-rubyspec-does-hotruby-implement/191932 "2010-07-20T22:39:35Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![akm](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/57b2e6/32.png) [@akm](https://www.ruby-forum.com/u/akm)\
**Post date:** [July 20, 2010, 10:39pm UTC](https://www.ruby-forum.com/t/how-much-of-the-rubyspec-does-hotruby-implement/191932/1 "2010-07-20T22:39:35Z")

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Greetings,

Does anyone know how feature complete hot ruby is?  
That is, how much of the rubyspec it implements?

Also, does anyone know if it uses 1.8 or 1.9 syntax?

Thanks,  
Andrew McElroy  
[TryRuby.org](http://TryRuby.org)

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<div class="post-metadata">

**Author:** ![akm](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/57b2e6/32.png) [@akm](https://www.ruby-forum.com/u/akm)\
**Post date:** [July 20, 2010, 10:57pm UTC](https://www.ruby-forum.com/t/how-much-of-the-rubyspec-does-hotruby-implement/191932/2 "2010-07-20T22:57:09Z")

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On Tue, Jul 20, 2010 at 3:38 PM, andrew mcelroy [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)  
wrote:

> Greetings,
> 
> Does anyone know how feature complete hot ruby is?  
> That is, how much of the rubyspec it implements?
> 
> Also, does anyone know if it uses 1.8 or 1.9 syntax?  
> I realize that it targets ruby 1.9. I don’t know why I asked this.

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<div class="post-metadata">

**Author:** ![akm](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/57b2e6/32.png) [@akm](https://www.ruby-forum.com/u/akm)\
**Post date:** [July 21, 2010, 1:56am UTC](https://www.ruby-forum.com/t/how-much-of-the-rubyspec-does-hotruby-implement/191932/3 "2010-07-21T01:56:20Z")

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andrew mcelroy wrote:

> Does anyone know how feature complete hot ruby is?  
> That is, how much of the rubyspec it implements?

I don’t know, but I have faint memories of reading an article which  
mentioned that it didn’t even implement enough of Ruby to _run_ the  
specs, let alone pass them. Although that was a long time ago, and it  
probably has significantly improved since then.

> Also, does anyone know if it uses 1.8 or 1.9 syntax?

Neither, actually. HotRuby doesn’t run Ruby, it runs YARV bytecode.  
So, if you can get your hands on a compiler that spits out YARV  
bytecode, HotRuby runs it.

One such compiler is obviously the one built into YARV itself, which  
implements Ruby 1.9, but there’s nothing stopping you from writing a  
compiler which compiles Ruby 1.8 or indeed _any_ language to YARV  
bytecode. Indeed, I vaguely remember reading about a Lisp  
implementation which targets YARV bytecode.

jwm