I’m making my way through the The book of F# and been playing with implementing the RPN calculator

personally I found it quite interesting to see my choices during this small exercise, especially the use of Option types to handle error cases comes quite naturally. Another interesting thing I found was that, similar to how I would write the same thing in Lisp, it is very obvious to define functions inside other functions to hide implementation details I would like to give a name to but don’t want to share with the rest of the program.