Re: MethodHandle loop body parameters and Stream.reduce accumulator parameters are not in the same order

[Michael Haupt]

Hi Rémi,

I think you can stay tuned for the fix to JDK-8151179; part of what it 
addresses is just this. The changes are currently in the CCC loop but should 
come up for public re-review soon.

Best,

Michael

> Am 14.09.2016 um 15:19 schrieb Remi Forax :
> 
> Hi everybody,
> i've just found that the parameters of the body (a MethodHandle) of 
> MethodHandles.countedLoop (both overloads) and iteratedLoop are not in the 
> same order as the accumulator in methods Stream.reduce, given that they 
> conceptually represent the same thing, i think the first two parameters of 
> body should be swapped in countedLoop and iteratedLoop.
> 
> in Stream:
>  U reduce(U identity,
> BiFunction accumulator,
> BinaryOperator combiner)
> so this is equivalent to value = accumulator(value, element)
> 
> In MethodHandles:
>   MethodHandle iteratedLoop(MethodHandle iterator,
> MethodHandle init,
> MethodHandle body)
>  with value = body(element, value, iterable)
> it should be
>  value = body(value, element, iterable).
> 
> Same things for 
>   MethodHandle countedLoop(MethodHandle start,
>MethodHandle end,
>MethodHandle init,
>MethodHandle body)  
>  it should be
>value = body(value, index, array); 
>  instead of
>value = body(index, value, array);
> 
> the other loop combinators do not be to be changed.
> 
> cheers,
> Rémi
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MethodHandle loop body parameters and Stream.reduce accumulator parameters are not in the same order

[Remi Forax]

Hi everybody,
i've just found that the parameters of the body (a MethodHandle) of 
MethodHandles.countedLoop (both overloads) and iteratedLoop are not in the same 
order as the accumulator in methods Stream.reduce, given that they conceptually 
represent the same thing, i think the first two parameters of body should be 
swapped in countedLoop and iteratedLoop.

in Stream:
 U reduce(U identity,
 BiFunction accumulator,
 BinaryOperator combiner)
 so this is equivalent to value = accumulator(value, element)

In MethodHandles:
   MethodHandle iteratedLoop(MethodHandle iterator,
 MethodHandle init,
 MethodHandle body)
  with value = body(element, value, iterable)
it should be
  value = body(value, element, iterable).

Same things for 
   MethodHandle countedLoop(MethodHandle start,
MethodHandle end,
MethodHandle init,
MethodHandle body)  
  it should be
value = body(value, index, array); 
  instead of
value = body(index, value, array);

the other loop combinators do not be to be changed.

cheers,
Rémi
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