Abstract
Effect handlers are a programming language construct able to express and combine diverse computational features such as backtracking, stream redirection, multiple scheduling strategies, or continuations. This flexibility comes as no surprise since handlers are based on even more versatile homomorphisms of algebraic theories. Even though the design of handlers witnessed multiple iterations and extensions, their mathematical core remained unchanged.
This seminar discusses the discovery of effect handlers and initial considerations behind their design, in particular steps required when translating a mathematical concept into a useful programming tool. We shall also take a look at subsequent research on handlers, for example various effect systems or an efficient transpiler to OCaml, comparing features guided by mathematics and those with a more practical motivation.
