like map erlang function

gistfile1.groovy

/*
Closure with 2  arguments:
  -closure_F is the function F
  -list_L is list L
*/
def map = {  list_L , closure_F -> 
    
    // Delegate is the elment to actue over
    delegate.collect(list_L) { element ->
            
        closure_F(element)
    }          
 
}
 
// Add to metaClass of List dynamically with name "map"    
List.metaClass.map = map 
 
def list = [1,2,3,4] 
def newList = []  
 
list.map(  newList  ){ it * 2 } 
 
assert newList == [2,4,6,8] 
assert list == [1,2,3,4]