Fibonacci sequence generator

fib_generator.coffee

class fib_generator
  constructor: ->
    last = 0
    current = 1
    @first = ->
      last = 0
      current = 1
    @next = ->
      temp = last
      last = current
      current = current + temp

fib = new fib_generator

fib_generator.js

fib = (function() {
  var current = 1,
      next = 1;
  return {
    first: function() {
      current = next = 1;
      return current;
    },
    next: function() {
      var temp = current;
      current = next;
      next = current + temp;
      return current;
    }
  }
})()

fib_generator_compact.js

fib=(function(a,b){a=b=1;return{first:function(){return a=b=1;},next:function(){return a=[b,b+=a][0];}}})()

fib_generator_full.js

fib = (function () {
  var s = [ 1 , 1 ],
      i = 0;
  return {
    first: function() {
      i = 0;
      return s[ i ];
    },
    next: function() {
      i = i + 1;
      if ( typeof( s[ i ] ) === "undefined" ) {
            
        s[ i ] = s[ i - 2 ] + s[ i - 1 ];

      }
      return s[ i ];
    },
    nth: function( n ) {
      while ( typeof( s[ n ] ) === "undefined" ) {
        this.next();
      }
      return s[ n ];
    },
    take: function( n ) {
      // Ensure that the nth element has been generated
      this.nth( n );
      return s.slice( 0 , n );
    }
  };
})()

fib_generator_full_compact.js

fib=(function(s,i){s=[1,1];i=0;return{first:function(){return s[i=0];},next:function(){return s.length<=++i?s[i]=s[i-2]+s[i-1]:s[i];},nth:function(n){while(s.length<=n)this.next();return s[n];},take:function(n){this.nth(n);return s.slice(0,n);}};})()

fib_generator_memo_compact.js

fib=(function(s,i){s=[1,1];i=0;return{first:function(){return s[i=0];},next:function(){return s.length<=++i?s[i]=s[i-2]+s[i-1]:s[i];}}})()

A series of generator functions for the Fibonacci sequence. A basic one, one including memoization, and a final one incorporating a large set of generator functionality (first,next,nth, and take).