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From Paul King <pa...@asert.com.au>
Subject Re: precedence rules for power operator vs -, +, ++, --
Date Sun, 07 Jun 2015 11:50:18 GMT

What do lua/python/ruby return for "-8 - 1"?

On 7/06/2015 8:40 PM, Jochen Theodorou wrote:
> Am 06.06.2015 13:08, schrieb Paul King:
> [...]
>> def x = 5
>> assert -x ** 2 == -25  // treated as -(x ** 2)
>> assert --x ** 2 == 24  // treated as --(x ** 2)
>>
>> This behavior is different to the other operators and different to what
>> the comments in the grammar describe as the intended behavior but the
>> order of two rules was presumably accidentally reversed in the grammar.
>>
>> After the change, the following executes:
>>
>> def x = 5
>> assert -x ** 2 == 25   // treated as (-x) ** 2
>> assert --x ** 2 == 16  // treated as (--x) ** 2
>
> I just checked Ruby and Python and there -2**4 will return -16, same for -2^4 in Lua.
So now I am wondering if that is the right thing for unary minus
>
> bye blackdrag
>


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