Cartesius

Implementing Event Correlation Patterns with Algebraic Effects

Or: Solving the Expression Problem for Joins

Cartesius is a DSL for defining expressive n-way joins over asynchronous event sequences. Joins exists in different domains, e.g., stream-relational algebra, complex event patterns, (functional) reactive programming and concurrent programming (join calculus). With Cartesius, we can define join variants in a uniform and structured manner, solving the expression problem. The workhorse are algebraic effects and handlers, which we employ to interpret declarative join pattern specifications in different ways.

Versions

This repository features implementations of Cartesius in different languages:

• Multicore OCaml in the ocaml/ subfolder (actively developed).

• Koka in the koka/ subfolder (currently not maintained). Please check out the old branch for the last working version.

Contributors

• I thank @namin for collaborating with me on the initial Koka prototype.

References

Versatile Event Correlation with Algebraic Effects (ICFP 2018) by Oliver Bračevac, Nada Amin, Guido Salvaneschi, Sebastian Erdweg, Patrick Eugster and Mira Mezini (pdf).

Type-safe, Polyvariadic Event Correlation (draft, 2019) by Oliver Bračevac, Guido Salvaneschi, Sebastian Erdweg and Mira Mezini (pdf).