Module actyxos_data_flow::flow

Opinionated simplification of the differential-dataflow API

Differential Dataflow provides great flexibility in terms of time tracking, multiplicity tracking, etc. This comes at the cost of many type parameters and lower quality type inference and tab completions, in particular in IDEs. This module fixes most of the type parameters, leaving open only the type of data in a collection. It also contrains the signature of the user-provided closures to reject unsuitable data (for example non-static references) at their place of introduction instead of presenting the error when trying to transform the resultant collection.

The general shape of a differential dataflow remains the same:

use actyxos_data_flow::flow::{Scope, Flow, Input, Stateless};

fn mk_logic<'a>(scope: &mut Scope<'a>) -> (Input<String>, Flow<'a, usize, Stateless>) {
    let (input, flow) = Flow::new(scope);
    let out = flow.map(|s: String| s.len());
    (input, out)
}

Note how the returned flow tracks the information of whether stateful combinators are used. There is a .map_mut() method that allows a stateful closure to be passed in, which will make the example not compile unless also switching the declared output type to Stateful.

Structs

Flow	Differential dataflow Collection wrapper
Grouped	An arrangement of a collection by key
Input	An input to a Flow
Output	An output of a dataflow graph
Probe	A probe measuring the propagation of progress within the dataflow
Stateful	Marker for stateful flows that need to see previous inputs again after restart
Stateless	Marker for stateless flows that do not need to be warmed up with previous inputs

Traits

NeedsState

Marker trait that tracks whether a Flow needs to keep state.

Type Definitions

Scope

Top-level scope type where flows usually are created in.