This is a common approach in compilers. It makes things more manageable. Each of the languages is simpler but has more constraints until you reach to the constr

This is a common approach in compilers. It makes things more manageable. Each of the languages is simpler but has more constraints until you reach to the constraints that machine provides. Here is example of compiler construction class: http://web.cs.ucla.edu/~palsberg/course/cs132/project.html http://web.cs.ucla.edu/~palsberg/course/cs132/project.html The mid languages were named after character in Winnie the Pooh, you can also see how factorial example looked in each stage.