import { isFunction } from '../util'

export interface Comparable {
  equals: (rhs: any) => boolean;
  gt: (rhs: any) => boolean;
  geq: (rhs: any) => boolean;
  lt: (rhs: any) => boolean;
  leq: (rhs: any) => boolean;
}

export function isComparable (arg: any): arg is Comparable {
  return (
    arg &&
    isFunction(arg.equals) &&
    isFunction(arg.gt) &&
    isFunction(arg.geq) &&
    isFunction(arg.lt) &&
    isFunction(arg.leq)
  )
}