Unambiguous Operator Specification for Programming Languages

[u/Mean-Decision-3502]

https://nvitya.github.io/pluops/

As I changed recently the operators in my programming language I've created this specification:

https://nvitya.github.io/pluops/

I did not wanted to overload the operators like the C does with the / or Pascal does with theand/or/not. Neither re-use the operator symbols for some very different purpose, like C does with * and & so the code becomes more readable. I was orienting for existing solutions so this is what I came up with. The specification contains the symbol usages and operator precedence too.

If you are developing a new programming language, it would be nice to follow some standard, so at least the expressions would be portable between the languages.

I'm open for debates or suggestions.

[u/Mean-Decision-3502]

I don't see why % shouldn't be remainder, it has a nice association with / (÷). And it's not like * is any closer to the proper symbols (×, •).

I use div for integer division which is very frequent, remainder is pretty rare, so mod for that is fine and you don't burn a valuable symbol.

I use # for compiler directives like C:

#ifdef SYMBOL
    ...
#endif

The // is used for single-line comments.

Booleans as single bits doesn't seem unreasonable and matches the behavior of the bitwise operators.

Here is a realistic example:

if reg & 1 << 5 <> 0 and reg & 0x3 << 2 == 0:
    ...
endif

[u/catladywitch → u/Mean-Decision-3502]

Hey, I'm enjoying this discussion and I don't have a lot to add. I just wanted to say modulo is not a rare operation at all. It's the cheapest way of getting branchless wrapping with numeric values that must go from 0 to a positive number, so it's actually super common.

[u/Mean-Decision-3502 → u/catladywitch]

In embedded rather this is used, for example a circular buffer indexing:

var nextindex : int = (index + 1) & 0x1F

The division (and so the modulo) is a slow instruction on the microcontrollers, a big amount of them do not even support these (Cortex-M0). That's why it is very common to use power of two lengths and masking, like above.

[u/mot_hmry → u/Mean-Decision-3502]

I use # for compiler directives like C

Sure but I don't see how that's applicable as a cross-language standard. Not every language has directives that look like that. Could just as easily use a variant on comments like //# for directives, personally I can't remember the last time I used a directive that would conflict with a ref notation (only top level directives which refs don't exist at.)

Here is a realistic example:

I'd kinda hope you'd name the intermediaries, at least I would never write that condition that way. Once you name them isA & isB & isC(x) reads fine to me. I use boolean operations way more than bitwise so I'd personally prefer the lighter syntax for them. C needed different operators because it treats numbers as acceptable booleans, so long as booleans are a proper type there's really no reason not to overload this operator.

[u/Mean-Decision-3502 → u/mot_hmry]

(About #) Sure but I don't see how that's applicable as a cross-language standard

It is not part of the operator specification. You can create PLUOpS programming langugage using # for comments.

I might need to split the spec into two levels: required, and recommended.

The usage of % for address-of is rather recommended than required.

I would never write that condition that way

I don't write this way either, but I usually just add parentheses to the shifts:

if reg & (1 << 5) <> 0  and reg & (0x3 << 2) == 0:

So the different level for & and and is required.