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From Steve Loughran <ste...@apache.org>
Subject Re: Defining Hadoop Compatibility -revisiting-
Date Mon, 16 May 2011 10:50:03 GMT
On 13/05/11 05:52, Milind Bhandarkar wrote:
> Ok, my mistake. They have only asked for documented specifications. I may
> have been influenced by all the specifications I have read. All of them
> were in English, which is characterized as a natural language.
>
> But then, if you are proposing a specification in a non-natural-language,
> isn't that called a test suite ? Or is there a middle ground ?

There's formal specifications in languages like Z, We don't really want 
to go there if we can help it, as all it lets you do is prove 
correctness if you're a mathematician, and I haven't found the 
mathematician plugin for Jenkins yet.

There's also languages like Extended ML, from Sanella et al, who may be 
familiar to Doug from his time in the frozen lands of the north 
(edinburgh):
	http://homepages.inf.ed.ac.uk/dts/eml/
Some of the bits of spec in this language can be executed, as long as 
you don't start declaring things about state over time. Again, though, 
it's hard work, unless your target language is, say ML or Haskell, as 
there you can jump from Specification to Implementation fairly rapidly

Where the formal stuff is good for is things like consistency protocols, 
so I'd hope someone did get out the proofs for Zookeeper, so the rest of 
us can rely on it working.

-Steve



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