// Total ordering of primitive types

export const compareNumbers = x => y => {
  if (typeof(x) !== 'number' || typeof(y) !== 'number') {
    throw new Error(`was only meant to compare numbers! got ${x} and ${y}`);
  }
  return (x < y) ? -1 : (x > y) ? 1 : 0;
}

export const compareStrings = x => y => {
  if (typeof(x) !== 'string' || typeof(y) !== 'string') {
    throw new Error(`was only meant to compare strings! got ${x} and ${y}`);
  }
  return (x < y) ? -1 : (x > y) ? 1 : 0;
}

export const compareBools = x => y => {
  if (typeof(x) !== 'boolean' || typeof(y) !== 'boolean') {
    throw new Error(`was only meant to compare booleans! got ${x} and ${y}`);
  }
  return x - y;
};

// The Unit-type has only one instance, which is equal to itself:
export const compareUnits = _ => _ => 0;

// Symbols are encoded as strings
export const compareSymbols = a => b => compareStrings(a)(b);