  We introduce a new diagrammatic notation for representing the result of
(algebraic) effectful computations. Our notation explicitly separates the
effects produced during a computation from the possible values returned, this
way simplifying the extension of definitions and results on pure computations
to an effectful setting. Additionally, we show a number of algebraic and
order-theoretic laws on diagrams, this way laying the foundations for a
diagrammatic calculus of algebraic effects. We give a formal foundation for
such a calculus in terms of Lawvere theories and generic effects.
