Re: Operator precedence and unary minus

[dyngeccetor8 <dyngeccetor8@...>]

On 05/22/2018 07:52 AM, Egor Skriptunoff wrote:
> On Tue, May 22, 2018 at 1:57 AM, dyngeccetor8 wrote:
> 
>>
>> Lua 5.3 has four unary operators: "#", "~", "-", "not".
>> Lowering priority of "-" looks inconsistent.
>> Lowering priority of all unary operators hurts more than cures.
>>
>>
> Unary operators are very different.
> Why do you want all unary operators to have the same priority?
> I see no point in it.
> 

I find it easy to state that all unary operators have the same
priority than to explain why unary minus is so different.

By the way, "~ - 1" is "0" now. After you change it'll become
"- ~ 1" which is "2".

Your well explained case with non-symmetric "mod" is one of
features of languages which have to be kept in mind.
Just like platinum question about "broken" "#" operator.

--

I believe all unary operators should have highest priority.

Current operator priorities:

  3.4.8 – Precedence

  Operator precedence in Lua follows the table below, from lower to higher priority:

       or
       and
       <     >     <=    >=    ~=    ==
       |
       ~
       &
       <<    >>
       ..
       +     -
       *     /     //    %
       unary operators (not   #     -     ~)
       ^

  -- https://www.lua.org/manual/5.3/manual.html

So "- 2 ^ 2" is "-4.0" and to square length of string "s" you
have to write "(# s) ^ 2".

-- Martin