Incremental.NET

A library for incremental computations.

Based on janestreet/incremental for OCaml. Also inspired by Gjallarhorn.

Usage -- see tests

use Incr = new Incremental()
let Var = Incr.Var

let myOrders = Var.Create([100; 150; 200])
use maxOrder = Incremental.map Incr myOrders List.max
use minOrder = Incremental.map Incr myOrders List.min
use orderRange = Incremental.map2 Incr maxOrder minOrder (-)

let log = ResizeArray<string>()
use maxChanged = maxOrder.Subscribe (fun maxOrder -> log.Add(sprintf "Max changed to %d" maxOrder))

let worldVersion = Incr.Stabilize()

Assert.AreEqual([100; 150; 200], myOrders.Value)
Assert.AreEqual(200, maxOrder.Value)
Assert.AreEqual(100, minOrder.Value)
Assert.AreEqual(100, orderRange.Value)

myOrders.SetValue([300;400;500])
Incr.Stabilize() |> ignore

Assert.AreEqual(500, maxOrder.Value)

Assert.AreEqual("Max changed to 500", Seq.last(log))

Differences from Gjallarhorn:

• Thread safety (easy for user to make sure they get a consistent view)
• Control when computations happen (user must call .Stabilize())
• Fewer features, less code

Roadmap

• More tests
• Nuget release
• Incremental.Bind support

See also

• Gjallarhorn for F#.
• https://opensource.janestreet.com/incremental/