Not sure if this has been linked before, but just finished (and enjoyed!) this 1994 CMU paper about the structure editors that were made for introductory programming classes (namely GNOME, MacGnome, and ACSE): https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.110.3146&rep=rep1&type=pdf Includes some good insights for those creating structure editors.