[muth02446]

This reminded me of two other recommendations:

1) write a pretty printer early on (I had one for the s-expr based syntax and one for the concrete syntax I introduced later) This will allow you to automatically apply the syntax changes on the example code you have written in your PL with only very little programming

2) instead of parser generators use recursive descent + Pratt parsing Pratt parsing is a little bit magical at first but it is easy to develop a working intuition without understanding all the details of the algorithm.