const gt = x => y => x > y;
const lt = x => y => x < y;

const or = x => y => x || y;
const and = x => y => x && y;

const type = x => typeof x;
// like type('foo') => 'string';
// like type(undefined) => 'undefined';

const equal = x => y => x === y;
// like eq(false)(false) => true;
// like eq(false)(true) => false;

const nequal = x => y => x !== y;
// like neq(false)(true) => true;
// like neq(true)(true) => false;

const $typeof = x => y => equal(x)(type(y));
// like $typeof('string')('foo') => true;
// like $typeof('undefined')(undefined) => true;
// like $typeof('boolean')('fizzbuzz') => false;

const undef = x => $typeof('undefined')(x);
// like undef(undefined) => true;
// like undef('foo') => false;

const def = x => nequal(type(x))('undefined');
// like def(undefined) => false;
// like def('foo') => true;

const gte = x => y => or(gt(x)(y))(eq(x)(y));
const lte = x => y => or(lt(x)(y))(eq(x)(y));

const ss = x => y => or(or(and(gt(x)(y))(1))(and(gt(y)(x))(-1)))(0);
// like ss(10)(1) => 1;
// like ss(1)(10) => -1;
// like ss(1)(1) => 0;

const is = x => y => x.__proto__.isPrototypeOf(new y());
// like is(x)(Array); => true;
// like is(true)(String) => false;

const is_not = x => y => equal(is(x)(y))(false);

const is_null = x => equal(x)(null);

export {
  gt,
  lt,
  and,
  or,
  type,
  equal,
  nequal,
  undef,
  def,
  gte,
  lte,
  ss,
  is,
  is_not,
  is_null
};