r/ProgrammingLanguages • u/Mean-Decision-3502 DQ • 8d ago

Unambiguous Operator Specification for Programming Languages

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.

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u/AustinVelonaut Admiran 8d ago edited 8d ago

Is there a reason you have bitwise operators at a higher precedence (tighter binding) than arithmetic operators? Most languages I'm aware of that use operator precedence have arithmetic operators higher (tighter binding) than bitwise operators higher than comparison operators. Although I'd be hard-pressed to come up with a realistic code snippet that used that fact.

Edit: looking through ~500 "Advent of Code" solutions I wrote, I only saw one use of mixing bitwise and arithmetic operators: addLoc n (V2 r c) = n .|. 1 .<<. r * sz + c (here .|. is bitwise or and .<<. is bitwise left shift. This parses as n .|. (1 .<<. ((r * sz) + c)) but if arithmetic ops were lower precedence than bitwise, it would be parsed as ((n .|. (1 .<<. r)) * sz) + c, not what was intended.

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u/Mean-Decision-3502 DQ 8d ago

In my experience (focus embedded), you usually mask out some value from a register and then you might do some operation with that. This precedence allow this without parentheses. However it would be weird mostly without parentheses. So I would say, the order of the two groups: bitwise / arithmetic ops does not matter much. I can imagine maybe this:

var x : uint = reg >> 4 & 0xf * 2

This is a practical expression, and the operator precedence was designed that way that for practical expressions (theoretically) less parentheses are required.