TypePromotion

TypePromotion exposes the promotion policy used by core arithmetic:

Integer (level 0) → Rational (level 1) → RationalInterval (level 2)

Most callers can use instance methods directly. This class is useful to evaluators and other dispatch layers that receive heterogeneous core values.

Inspection and conversion

Static method	Result
`getTypeLevel(value)`	`0`, `1`, or `2`; unknown types throw
`integerToRational(integer)`	Denominator-one `Rational`
`rationalToInterval(rational)`	Point `RationalInterval`
`integerToInterval(integer)`	Point interval through both promotion steps
`promoteToLevel(value, level)`	Upward promotion; invalid levels and demotion throw
`promoteToCommonType(a,b)`	Pair promoted to the higher input level

import {
  Integer,
  Rational,
  RationalInterval,
  TypePromotion,
} from "@ratmath/core";

TypePromotion.getTypeLevel(new Rational(1, 2)); // 1

const [a, b] = TypePromotion.promoteToCommonType(
  new Integer(1),
  new RationalInterval(2, 3),
);

a instanceof RationalInterval; // true
b instanceof RationalInterval; // true

Operations

Static method	Behavior
`add(a,b)`	Promote, then add
`subtract(a,b)`	Promote, then subtract
`multiply(a,b)`	Promote, then multiply
`divide(a,b)`	Promote, then divide; preserves smart integer division
`eNotation(base,exponent)`	Apply exact multiplication by `10^exponent`
`power(base,exponent)`	Call `base.pow(exponent)`
`multiplyPower(base,exponent)`	Call `mpow` when available, otherwise `pow`
`negate(value)`	Preserve the value’s core type while negating

TypePromotion.add(new Integer(2), new Rational(1, 3)).toString();
// "7/3"

TypePromotion.divide(new Integer(8), new Integer(4)).toString();
// "2"

TypePromotion.divide(new Integer(8), new Integer(3)).toString();
// "8/3"

For intervals, power and multiplyPower intentionally differ; see RationalInterval.

Syntactic classification

determineTypeFromString(text) is a lightweight classifier, not a validator:

TypePromotion.determineTypeFromString("42");       // "integer"
TypePromotion.determineTypeFromString("3/4");      // "rational"
TypePromotion.determineTypeFromString("1:2");      // "interval"
TypePromotion.determineTypeFromString("1.2[+-1]"); // "interval"

It reports a likely type from punctuation and may classify malformed text. Use parseNumber when validation and value construction are needed.