function printArray(array){
  for(var i=0;i<array.length;i++){
     print(array[i]); 
  }   
}

function forEach(array,action){
  for(var i=0;i<array.length;i++){
    action(array[i]); 
  } 
}
forEach(["a","b","c"],print);

function sum(numbers){
  var total = 0;
  forEach(numbers,function(number){
     total+=number;
  })   
  return total;  
}

function negate(func){
  return function(x){
    return !func(x); 
  }
}
var isNotNaN = negate(isNaN);
isNotNaN(NaN);

传说中的组合模式：
function compose(f1,f2){
   return function(){
      return f1(f2.apply(null,arguments));
   };
}

var isNotNaN = compose(op["!"],isNaN);
isNotNaN(5); =>true

function reduce(combine,base,array){
  forEach(array,function(element){
    base = combine(base,element);
  });
}

function add(a,b){
 return a+b;
}

reduce(add,0,array);

function map(func,array){
  var result = [];
  forEach(array,function(element){
    result.push(func(element));
  });
  return result;
}

map(Math.round,[0.01,2,9,Math.PI]);

function splitParagraph(text){
  function split(pos){
     if(pos == text.length) return [];
     else if(text.charAt(pos) == "*"){
         var end = findClosing(“*”，pos+1);
         frag = {type：“emphasized”,content:text.slice(pos+1,end)};
         return [frag].concat(split(end+1));  //回调
     } else if(text.charAt(pos) == "{"){
         var end = findClosing(“{”，pos+1);
         frag = {type：“emphasized”,content:text.slice(pos+1,end)};
         return [frag].concat(split(end+1));  //回调
     } else{
        var end = findOpeningOrEnd(pos),
           frag = {type:"normal",content:text.splice(pos+1,end)};
           return [frag].concat(split(end));

     }
  }
  function findClosing(character,from){
     var end = text.indexOf(character,from);
     if(end == -1) throw new Error("Missing closing ' "+character+"'");
     return end;
  }
  function findOpeningOrEnd(from){
     function indexOrEnd(character){
        var index = text.indexOf(character,from);
        return index = -1?text.length:index;
     }
     return Math.min(indexOrEnd("*"),indexOrEnd("{"));
  }
  
  return split(0);  
}

function split(){
   var pos = 0,fragments = [];
   while(pop<text.lenght){
      if(text.charAt(pos) == "*"){
         var end = findClosing("*",pos+1);
         fragments.push({type:"emphasized",content:text.slice(pos+1,end)});
         pos = end+1;
      }else if(text.charAt(pos) == "{"){
         var end = findClosing("}",pos+1);
         fragments.push({type:"footnote",content:text.slice(pos+1,end)});
      }
      else{
         var end = findOpeningOrEnd(pos);
         fragments.push({type：“footnote”,content:text.slice(pos,end)});
         pos = end;
      }

   }
   return fragments;
}

function partial(func){
   var knownArgs = arguments;
   return function(){
      var realArgs = [];
      for(var i=1;i<knownArgs.length;i++){ //from 1
        realArgs.push(knowArgs[i]);
      }
      for(var i=0;i<arguments.length;i++){
        realArgs.push(arguments[i]); 
      }
      return func.apply(null,realArgs);
   }
}

map(partial(op["+"],1),[0,2,4,6,8,10]); // op["+"] swithcase 的一个function