Should we distinguish the minus sign from the negative sign? In the set $\mathbb{C}$ of complex numbers, the minus sign "-" may be used for following:


*

*As a unary operator $-_u$, given a complex number $a$, $-_ua$ is the unique number (called the negative of a) $c$ such that $a+c=c+a=0$, where $0$ is the additive identity.

*As a binary opeartor $-_b$, given two complex numbers $a$ and $d$, $a-_bd$ is the sum of $a$ and $-_ub$.


Though $-_u$ and $-_b$ are closely related, they are completely different objects in mathematics: $_u$ is considered as a map from $\mathbb{C}$ to $\mathbb{C}$ while $-_b$ is a map from $\mathbb{C}\times\mathbb{C}$ to $\mathbb{C}$. As maps, they have the same codomain but different domains.
In some calculators such as TI nspire, two different keys are used for the two different meanings of $-$. However, in our everyday writing, we seldom differentiate the unary opeartor $-_u$ and $-_b$. Shouldn't we use diffrent symbols for them; after all, though closely related, they are different?
If we do not use different symbols for them, the following simple calculation appears confusing:
\begin{equation*}\begin{array}{c}
\phantom{\times9}-23\\
\underline{-\phantom{9}-15}
\\
\phantom{999}-8
\end{array}\end{equation*}
Also, I find the idea that in the same equation $-1-1=-2$, the first $-$ has different meaning from the second $-$ unsatisfactory.

First, note that there is already a distinction that is made, in the sense that you don't pronounce them the same: $$0-6=-6\qquad \text{"zero } \textbf{minus}\text{ six}=\textbf{negative}\text{ six}"$$
while other languages wouldn't - French, for instance, has "zéro moins six = moins six".
Now perhaps there is one case where it could be relevant to also point out the difference as you're writing, and that's when you're teaching at low level. Pupils get confused about the rules involving the $-$ sign partially because of this intentional mix-up by mathematicians and teachers (another, though related, source of confusion being the fact that you systematically write down the $-$ attached to negative numbers, while positive numbers don't have to have a $+$ at all times).
