composable lensOver constructs w/ Immutable.js instead of lodash's deepClone

immutable-lensover.js

function curry(fx) {
  var arity = fx.length;

  return function f1() {
    var args = Array.prototype.slice.call(arguments, 0);
    if (args.length >= arity) {
      return fx.apply(null, args);
    }
    else {
      return function f2() {
        var args2 = Array.prototype.slice.call(arguments, 0);
        return f1.apply(null, args.concat(args2)); 
      }
    }
  };
}

function simpleCompose(fn1,fn2){
  return function(x){
    return fn1(fn2(x));
  }
}

var lensOver = curry(function(keypath, fn, imobj){
  keypath = typeof keypath === "string"?[keypath]:keypath;
  return imobj.hasIn(keypath) ?
    imobj.setIn(keypath, fn(imobj.getIn(keypath))) :
    imobj;
});



var example  = Immutable.fromJS({name:'guy',job:{role:'dev',employer:'BSD'}}),
    toUpper = function(str){return str.toUpperCase();}


var upperName = lensOver('name',toUpper),
    fixDev = lensOver(['job','role'],function(str){return str.replace('dev','Developer')});

upperName(example).toJS();//returns {name:'GUY',job:{role:'dev',employer:'BSD'}}
fixDev(example).toJS();// returns {name:'guy',job:{role:'Developer',employer:'BSD'}}

simpleCompose(upperName,fixDev)(example).toJS();// returns {name:'GUY',job:{role:'Developer',employer:'BSD'}}