ThingLab is a visual programming environment implemented in Smalltalk and designed at Xerox PARC by Alan Borning. wikipedia 
– https://youtu.be/8uGV9hcIN_Y?t=1995
– https://ftp.squeak.org/goodies/ThingLab/
YOUTUBE z0CCG12ieiU Modularity 2016 Keynote - Alan Borning - Constraints and Modularity