Object algebras are a simple technique that solves a long-standing problem of extensibility in programming languages, called the expression problem. CWI-researcher Tijs van der Storm presented the technique at Joy of Coding 2014, a conference for software developers that took place in March 2014. The video registration of his talk is published online at InfoQ.
The concept of Object Algebras was invented by Bruno C. d. S. Oliveira of the University of Hong Kong and William R. Cook of the University of Texas at Austin. Tijs van der Storm participated in follow-up research, improving the technique.