https://icfp20.sigplan.org/details/ho...
Algebras give us a way to interpret or handle effectful computations, and can be used as a lifting of quantitative predicates. A coeffect producer describes the dynamics of the environment, which can be consulted by a program, or can be used to resolve issues raised by a program. In this talk, we discuss a method of using an interaction law between the program and the environment, to merge an environment dynamics given by a coalgebra into a handler of residual effects after interaction given by an algebra. This results in a new algebra that can handle the effects of the program, without interaction with the environment.