Monoidal stream computation
Monoidal categories provide an algebra of processes that compose sequentially and in parallel (MacLane). This algebra is abstract enough that it can deal with multiple paradigms of computation in a unified fashion: we have a monoidal category PAR of partial functions, a monoidal category STOCH of finite-support stochastic processes, or a monoidal category REL of relational queries. Moreover, monoidal categories have a practical graphical calculus in terms of string diagrams.
References: