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core.async

tags
clojure asynchronous CSP

Problems

  • Function chains make poor machines
  • Real world concurrency is exposed via callback API.

core.async in Use

Source
core.async in use

  • Transducers are really important for using core.async.

  • Use transducers as much as possible in channels and go block to avoid side effect.

  • Make sure to return the channels.

  • Disadvantage: async code pollutes the return type, problem with error handling, channels are IO and hence have side effects. It introduces non-determinism in the code.

  • Don't use async, unless required.

  • Pattern fetch and them conj all the result in a callback.

  • A good api for library creators is to ask the user to take the result of the asynchronous code as a callback.

  • Make a framework where the asynchronicity is set as an implemented detail. Remove it from the interface (user or API). You need to contains the asynchronicity and hide it from the business perspective. This yields, testable data, explicit data.

  • Reifying is the act of taking virtual and making it concrete. Intangible to tangible. The interceptors (enter, exit, on-error).

  • Dataflow and FRP. Nodes are connected via communication channels, each nodes takes and emits from on or more inputs/outputs, each node consists of a function that computes outputs ased on inputs. The advantage is that it Separates transformation from communication and connection. It is functionally pure, async code is removed from the user interface, connections are explicit, and any connections can be used.

  • Actor, connections are implicit, sending message inside user code, opqare state hidden in loop local.

Pattern in Pattern

  • Keep user space code pure;
  • Move the complexity of async out of the user space;
  • Make dependencies/connections between modules/components explicit (the system can introspect itself). It increase leverage;
  • Leverage this for easier testing;
  • Use core.async to enable cleaner abstractions, not as aned in itself.

Pitfalls

Sliding/dropping buffers still required to be put into channels

(def c (chan (sliding-buffer 10)))

To Read

See also (generated)