Why referential transparency matters...

reverse in 3 langauges

//this is valid Ruby, Python and JavaScript

myList = [1,2,3]
myList.reverse()
newList = myList.reverse()

//Q. What is the value of newList in each of those three languages??
//answers below!!!
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
//Answers
Ruby: newList == [3,2,1]
Python: newList == None
JavaScript: newList == [1,2,3]