functional-abstraction/measure Home Manual Reference Source

src/0-core/0-base/Measure.js

  1. /**
  2.  * Abstract Measure class.
  3.  */
  4. export class Measure {
  5. 	/**
  6. 	 * Constructor, stores the monoid.
  7. 	 */
  8. 	constructor(monoid) {
  9. 		this.monoid = monoid;
  10. 	}
  11.  
  12. 	/**
  13. 	 * Returns the zero measure according to the monoid.
  14. 	 */
  15. 	zero() {
  16. 		return this.monoid.zero();
  17. 	}
  18.  
  19. 	/**
  20. 	 * Adds measures together using monoid#plus.
  21. 	 */
  22. 	plus(a, b, c = undefined) {
  23. 		if (c === undefined) return this.monoid.plus(a, b);
  24.  
  25. 		return this.monoid.plus(a, this.monoid.plus(b, c));
  26. 	}
  27.  
  28. 	/**
  29. 	 * Returns the measure of an element. Must be implemented by classes
  30. 	 * extending Measure
  31. 	 */
  32. 	measure(_element) {
  33. 		throw new Error('measure : not implemented');
  34. 	}
  35. }