From: "stomar (Marcus Stollsteimer)" <redmine@...>
Date: 2012-11-22T23:30:15+09:00
Subject: [ruby-core:49880] [ruby-trunk - Bug #7331] Set the precedence of unary `-` equal to the precedence `-`, same for `+`


Issue #7331 has been updated by stomar (Marcus Stollsteimer).


@alexeymuranov: I understood that you were talking about parsing.

I refute your primary supposition. In the mathematical expression -2��3, the unary `-' can be interpreted both as a multiplication, (-1)��2��3, and as subtraction, 0 - 2��3. Both interpretations are equally valid. Which one you choose has no effect on the result.

I think there is no sense in discussing or speculating further, as long as you do not provide a citation that confirms your mere **assumption** that the "mathematical parsing rule" (I doubt there is one) is -(a * b). And which one feels more "natural" to you (or to any Ruby user) is no argument at all.

And BTW, I do not think anyone of us is really qualified enough in this field to decide on this issue.
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Bug #7331: Set the precedence of unary `-` equal to the precedence `-`, same for `+`
https://bugs.ruby-lang.org/issues/7331#change-33636

Author: alexeymuranov (Alexey Muranov)
Status: Rejected
Priority: Normal
Assignee: 
Category: core
Target version: 
ruby -v: 1.9.3


=begin
I will not be surprised if this proposal is rejected, because the compatibility would be a mess, but i feel i need to start a discussion.  This continues the discussion in #7328.

To the best of my knowledge, in mathematics the unary minus has the same precedence as the binary one.  However, in the expression

  - a * b

Ruby computes first (({-a})), and then the product.  This means that if i want (for whatever reason) to compute the expression in the natural order, i have to put the parentheses:

  - (a * b)

which looks very strange to me.  I would consider this a bug.
=end



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