>>

>>* this is ok
>>? 10-3-2
>>* typo 3 => bad result (better a syntax error !)
>>? 10--2
>>* Need a constraint in the grammar
>>? 10-(-2)
>>

>
>Why would that be wrong? If I substract 10 minus negative two, that is the same as 10 plus 2. What do you expect, and why?

Of course, but the question is how you should write this.
With 3 or more signs VFP fail! VFP requires brackets.
I'd rather the obligation of the brackets with 2 signs too.

Why this allow a small typo to create a valid expression,
but that is a calculation that the programmer did not want to do!
This may result in errors discovered after months,
you have lots of corrupted data
and to find the wrong expression you become crazy.

The only help they can give you the language of development is the syntax,
I prefer a rigid syntax, to avoid a future in a mental hospital.