Code readthrough, comments

[bisqwit]

I had a brief read through your cons_expr.hpp. Fascinating code. Assorted comments below:

Category: Great idea!

— [[nodiscard]] attribute on ++(int), --(int), begin() etc.

Category: Could be better?

— pow(): Could use the much more efficient binary exponentiation algorithm: for(result = 1; power != 0; power >>= 1, base *= base) if(power & 1) result *= base; (similarly /= for negative exponents)

Category: Why the discrepancy?

— pow(): Parameter is long long, but is iterated using int.
— parse_float(): Accepts "-.4" but not ".4".
— parse_float(): Accepts "13.4e2" and "13.4e-2". Accepts "13e2" but not "13e-2".

Category: Errors?

— parse_float(): Accepts "-e2".
— next_token(): Interprets both "a\"b" and "a\\"b" as valid string constants.