monad-code-pen

index.html

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monad-code-pen

A Pen by karl on CodePen.

License.

script.js

// // ex:1
// var safeProp = R.curry(function (x, o) { return R.of(o[x]); });
// var user = [{
//   id: 334,
//   name: "albert",
//   address: {
//     stre11et: {
//       number: 22,
//       name: 'hehe'
//     }
//   }
// },{
//   id: 2,
//   name: "albert",
//   address: {
//     street: {
//       number: 22,
//       name: 'Walnut St'
//     }
//   }
// }];
// // console.log(user.address.street.name);
// // safeProp('name')safeProp('street')safeProp('address')
// var getAddress = safeProp('address');
// var getStreet = safeProp('street');   
// var getName = safeProp('name');
// var ret = R.map(R.compose(R.chain(getName), R.chain(getStreet),getAddress))(user);
// console.log(ret);
// var Maybe = function(x) {
//   this.__value = x;
// }

// Maybe.of = function(x) {
//   return new Maybe(x);
// }

// Maybe.prototype.isNothing = function() {
//   return (this.__value === null || this.__value === undefined);
// }

// Maybe.prototype.map = function(f) {
//   return this.isNothing() ? Maybe.of(null) : Maybe.of(f(this.__value));
// }
// const a = Maybe.of({a: 1}).map((v)=>(v.c)).map((v)=>{v.b}).map((v)=>{v.ccc});
// // const a = Maybe.of({a: 1}).map(R.prop('b')).map(R.prop('dd'));
// // console.log(a);
// var duplicate = n => [n, n];
// const ret = R.chain(duplicate, [1, 2, 3]); //=> [1, 1, 2, 2, 3, 3]
// console.log(ret);

// truncate :: String -> String
var truncate = R.when(
  R.propSatisfies(R.gt(R.__, 10), 'length'),
  R.pipe(R.take(10), R.append('…'), R.join(''))
);

const getArea = function (payload) {
   return R.when(!R.isNil(payload.country.province.area), payload.country.province.area);
}
const area = getArea({
  country:
  {
    province: {
      area: '2121'
    }
  }
});
console.log(area);

scripts

<script src="http://npmcdn.com/ramda/dist/ramda.js"></script>