My PhD research (completed in 1996) was to create the SPARCL programming language. The dissertation is Seeing the Logic of Programming With Sets. From the abstract:
This dissertation studies the hypothesis that visual logic programming based on sets with partitioning constraints provides a superior basis for exploratory program- ming languages. Our research program is to design and implement such a program- ming language with an integrated development environment, and to analyze this implementation.
The programming language we have created is named SPARCL (Sets and Partitioning Constraints in Logic). It has the four elements of the hypothesis: it is a visual language, it is a logic programming language, it relies entirely on sets to organize data (which implies that programs are organized using sets, since programs can be viewed as data in this language), and it supports partitioning constraints on the contents of sets. In developing this language, we invented new visual language representation techniques (the automatically laid out “smooth” hyperedge in two and three dimensions) and a new kind of unification for logic programming (the partitioned set unification algorithm).
The SPARCL language was implemented in Logic Programming Associate’s (LPA) MacProlog32 on an Apple Macintosh. Unfortunately LPA stopped supporting MacProlog32. I started the XGP open source project to replace MacProlog32 so that I could continue SPARCL (and other projects). XGP almost succeeded…