40 columns                              |
>>> Unary negate.
-  foo  ;
<<<
-foo;
>>> Bitwise not.
~  foo  ;
<<<
~foo;
>>> Boolean not.
!  foo  ;
<<<
!foo;
>>> Prefix increment.
++  foo  ;
<<<
++foo;
>>> Prefix decrement.
--  foo  ;
<<<
--foo;
>>> Multiple prefix operators.
-  ~  !  foo;
<<<
-~!foo;
>>> Sequential `-` operators are not joined.
-  -  -  -foo;
<<<
- - - -foo;
>>> A `-` operator before a negative integer is not joined.
-  -1;
<<<
- -1;
>>> A `-` operator before a negative floating point number is not joined.
-  -1.2;
<<<
- -1.2;
>>> A `-` before a `--` is not joined.
-  --  foo;
<<<
- --foo;