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javascriptnode.jsreactive-programmingfrpbacon.js

Lazy.js based fibonacci to map Bacon.js interval?


I have a code to generate fib sequences with lazy.js

var fibF = function()
{
  var seq = []; //build sequence array in this closure
  var f = function(n)
  {
    var val;
    if (n <= 1)
    {
      val = 1; // as the Fib definition in Math
    }
    else
    {
      val = seq[n - 2] + seq[n - 1]; // as the Fib definition in Math
    }
    seq[n] = val;
    return val;
  };
  return f;
}();

var fibSequence = _.generate(fibF);  


/*  just for test
var fib_1000 =
  fibSequence
  .take(1000)  
  .toArray();  

console.log(fib_1000); 
//[ 1, 1, 2, 3, 5, 8, 13, 21, 34, 55,...........,4.346655768693743e+208 ]

*/

At the same time, I have a code of timer with Bacon.js

var B = require('baconjs');

var timeSequence = B
      .interval(1000); //every second
     
timeSequence 
    .onValue(function() 
      {
        console.log(require('moment')().format('MMMM Do YYYY, h:mm:ss')); 
        // print timestamps every second
      }); 

Then,

I want to map the the fibSequence onto timeSequence such as

var mySequence = fibSequence.map(timeSequence);

or

var mySequence = timeSequence.map(fibSequence);

Is it possible?

If so, please show me the way.

Any workaround solution is welcome.

Thanks.

EDIT working code:

//to simplify use Natrual, instead of Fib

var _ = require('lazy.js');
var __ = require('baconjs');

var natural = function(n)
{
  return n;
};

var _natural = _.generate(natural); //natural numbers
var __timer = __.interval(1000); //every second

var map_to__ = function(_seq, __seq)
{
  var it = _seq.getIterator();

  var sequence =
    __seq
    .map(function()
    {
      it.moveNext();
      return it.current();
    });

  return sequence;
};

var __mappedTimer = map_to__(_natural, __timer);

__mappedTimer
  .onValue(function(x)
  {
    console.log(x); // print every second
  });

Solution

  • I'm not sure whether this is the intended use of iterators, but it should work:

    var it = fibSequence.getIterator()
    var mySequence = timeSequence.map(function() {
        return it.moveNext() && it.current();
    });