[Javascript] Monads

Monads to nest computations. They is a pointed functor that adds mjoin and chain functions to combine other functors. Brian shows a number of code examples of different monads in action.

Functions: "Mjoin", "Chain"

Mjoin:

 var  setsearchinput = function (x) {return  (  #input    var  getsearchterm = function () { return  GetParam ( term   " , Location.search)}.toio ()  var  initsearchform = compose (Mjoin, map (setsearchinput), getsearchterm) Initsearchform ()  // => IO (Dom)  runio (Initsearchform ())  

"Getsearchterm" return a IO, so in "setsearchinput" we need to use map (), but itself would return another IO, so the Resul T is io (IO ()) and then we apply mjoin, the result would be "IO ()".

Chain

var chain =return  compose (mjoin, map (f))}

 var  setsearchinput = function (x) {return  (  #input    var  getsearchterm = function () { return  GetParam ( term   " , Location.search)}.toio ()  var  initsearchform = compose (chain  ( Setsearchinput), Getsearchterm) initsearchform ()  // => IO (Dom)  runio (Initsearchform ())  

var sendtoserver = HttpGet ('/upload')var uploadfromfile =  Compose (Chain (Sendtoserver), Chain (ReadFile), Askuser) uploadfromfile ('whatfile? '). Fork (LogErr, alertsuccess)

Requirejs.config ({shim: {}, Paths: {domready:'Https://cdnjs.cloudflare.com/ajax/libs/require-domReady/2.0.1/domReady.min', Ramda:'//cdnjs.cloudflare.com/ajax/libs/ramda/0.8.0/ramda.min', maybe:'Http://looprecur.com/hostedjs/v2/maybe', io:'Http://looprecur.com/hostedjs/v2/io', Future:'HTTP://LOOPRECUR.COM/HOSTEDJS/V2/DATA.FUTURE.UMD', Hcjs:'Http://looprecur.com/hostedjs/v2/hcjs'}}); Require (['Ramda',    'maybe',    'io',    ' Future',    'Hcjs',    'domready!'], function (_, maybe, io, future) {console.clear (); varRunio =Io.runio; //Exercise 1// ==========    //Use Safeget and mjoin or chain to safetly get the street nameConsole.log ("--------Start Exercise 1--------"); varSafeget =_.curry (function (x, O) {returnmaybe (o[x]);    }); varuser ={ID:2, Name:"Albert", Address: {street: {number: A, Name:'Walnut St'        }      }    };      function log (x) {Console.log (x.tostring ()); returnx; }    varEx1 = Compose (Mjoin, map (Safeget ('name'), Mjoin, Map (Safeget ('Street')), Safeget ('Address')); varEx1 = Compose (Chain (Safeget ('name')), Chain (Safeget ('Street')), Safeget ('Address')); Assertequal (Maybe ('Walnut St'), Ex1 (user)); Console.log ("Exercise 1...ok!"); //Exercise 2// ==========    //Use monads to get the href and then purely log it.Console.log ("--------Start Exercise 2--------"); varGethref =function () {returnLocation.href;    }.toio (); varPurelog =function (x) {console.log (x); returnx;    }.toio (); varEX2 =Compose (Chain (Purelog), gethref); Assertequal ("Http://run.jsbin.com/runner", Runio (EX2 (NULL))); Console.log ("Exercise 2...ok!"); //Exercise 3// ==========    //Use monads to first get the Post with Getpost () and then pass it's ID in to Getcomments ().Console.log ("--------Start Exercise 3--------"); varEx3 = Compose (Chain (Compose (getcomments, _.Get('ID')) , getpost); varEx3 = Compose (Mjoin, map (Compose (getcomments, _.Get('ID')) , Getpost) ex3 ( -). Fork (log, function (res) {assertequal (2, res.length); Console.log ("Exercise 3...ok!");    }); //HELPERS// =====================function Getpost (i) {return NewFuture (function (Rej, res) {setTimeout (function () {res () {id:i, title:'Love them futures'          }); },  -);    }); } function Getcomments (i) {return NewFuture (function (Rej, res) {setTimeout (function () {res) (["This class should is illegal","monads is like space burritos"]); },  -);    }); }  });

[Javascript] Monads