Access Global Object from Purescript

Main.js

"use strict";

// module Main

exports.instGlobal = function(name){
	return function (value) {
		global[name]=value;
		return global[name];
	}
}

exports.getGlobal = function(name){ return global[name] }

Main.purs

module Main where

import Prelude
import Control.Monad.Eff
import Control.Monad.Eff.Console

foreign import instGlobal :: String -> String -> String
foreign import getGlobal :: String -> String

main :: forall e. Eff (console :: CONSOLE | e) Unit
main = do
  log "Hello sailor!"

psci_session.md

> instGlobal "D3" "its me!"
  "its me!"

> getGlobal "D3"
   /clean/.psci_modules/node_modules/Prelude/foreign.js:230
   TypeError: Cannot read property 'length' of undefined
   at exports.showStringImpl (/clean/.psci_modules/node_modules/Prelude/foreign.js:230:12)
   at /clean/.psci_modules/node_modules/Control.Monad.Eff.Console/index.js:15:51
 ...

I changed the return to "" + Object.keys(global); on both foreign fns. The interesting thing is. That on the instGlobal the keys is existing and when calling getGlobal its not there anymore.

Therefore this exception.

The question is why?