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From Jochen Theodorou <blackd...@gmx.org>
Subject Re: About the native-lambda branch
Date Fri, 12 Jan 2018 11:48:05 GMT


Am 12.01.2018 um 04:05 schrieb Daniel Sun:
> Hi Nathan,
> 
>> What's will the differences be between closures and lambdas?
> The native lambda will have better performance than closure. In addition,
> native lambda, which conforms to Java specification,  is less versatile than
> closure, which is really powerful...

but I think you should then not use the closure inner class mechanism. I 
had a bit a look at your code, but there is a ton of things missing. I 
did also not understand the innclass attribute visit... I thought you 
need that only to enable reflection to find your inner classes. 
MethodHandles.Lookup is no such thing. And then I would also question 
the early transformation you do where you store the lambda as body in a 
method node... which resides in the current class and which may have a 
name conflicting with an existing name... and a name check is something 
I would not do in that ast builder. In fact I would do this logic just 
before or even in ACG. Otherwise you will always have trouble with code 
that transforms the lambda expression. And then again we miss totally 
the handling of local variables, not in the lambda. And actually there 
is a performance related decision to do here. if we follow the closure 
logic, there will be a wrapper containing the value of the local 
variable, which is then used in the lambda. This costs. Not much, but it 
does. Since in Java you have only quasi final variables allowed, you do 
not need any wrapper. Not using the wrapper means less Closure 
implementation code we can use. But this wrapper also has quite special 
handling in many areas, like the VariableScopeVisitor. Oh yes... should 
you go with one inner class for all lambdas, then you have to add bridge 
methods to be able to access private fields in the outer class.

bye Jochen

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