side-effectis a general term in computer science. In the context of an app, it means any interaction with the world outside of the internal logic of your app. Typical examples of a include API requests, analytics, logging, local storage, and so on.
aperturecontrols the streams of data which enter Refract.
effectvalues in response.
effectis any value, passed from an
handler. These can be any value: numbers, strings, booleans, etc - you get to decide how to structure your effects.
handlercauses side-effects in response to any
effectvalue output by the
dispatchfor example), but could also include external side-effects which do not loop back into your app (such as localstorage or analytics).
errorHandlercauses side-effects in response to any fatal error occurring within your
errorHandler. Usually, you would be expected to log this error for further investigation.