Minimal Adaptive Cells (fable compatible)

An implementation of minimal adaptive cells

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type Cell<'T>(initial: 'T) =
    let mutable value = initial
    let mutable listeners : (unit -> unit) list = []  
    member _.Value = value
    member _.Set v =
        value <- v
        for l in listeners do l()
    
    member _.Subscribe(callback: unit -> unit) =
        listeners <- callback :: listeners

type RuleBuilder() =
    member _.Bind(cell: Cell<'T>, f: 'T -> unit) =
        f cell.Value
        cell.Subscribe(fun () -> f cell.Value)
    member _.Return(x) = x
    member _.Delay(f: unit -> unit) = f()
    member _.Zero() = () 

let rule = RuleBuilder()

// Define some reactive cells.
let a = Cell(3)
let b = Cell(4)
let sum = Cell(0)

// Create a reactive rule that computes the sum of a and b.
rule {
    let! va = a
    let! vb = b
    sum.Set (va + vb)
}

printfn "Initial sum: %d" sum.Value

// Changing 'a' will automatically update the computed sum.
a.Set 10
printfn "Updated sum: %d" sum.Value

Multiple items
type Cell<'T> =
  new : initial:'T -> Cell<'T>
  member Set : v:'T -> unit
  member Subscribe : callback:(unit -> unit) -> unit
  member Value : 'T

--------------------
new : initial:'T -> Cell<'T>

val initial : 'T

val mutable value : 'T

val mutable listeners : (unit -> unit) list

type unit = Unit

type 'T list = List<'T>

Multiple items
module Set

from Microsoft.FSharp.Collections

--------------------
type Set<'T (requires comparison)> =
  interface IReadOnlyCollection<'T>
  interface IComparable
  interface IEnumerable
  interface IEnumerable<'T>
  interface ICollection<'T>
  new : elements:seq<'T> -> Set<'T>
  member Add : value:'T -> Set<'T>
  member Contains : value:'T -> bool
  override Equals : obj -> bool
  member IsProperSubsetOf : otherSet:Set<'T> -> bool
  ...

--------------------
new : elements:seq<'T> -> Set<'T>

val v : 'T

val l : (unit -> unit)

val callback : (unit -> unit)

Multiple items
type RuleBuilder =
  new : unit -> RuleBuilder
  member Bind : cell:Cell<'T> * f:('T -> unit) -> unit
  member Delay : f:(unit -> unit) -> unit
  member Return : x:'a -> 'a
  member Zero : unit -> unit

--------------------
new : unit -> RuleBuilder

val cell : Cell<'T>

val f : ('T -> unit)

property Cell.Value: 'T with get

member Cell.Subscribe : callback:(unit -> unit) -> unit

val x : 'a

val f : (unit -> unit)

val rule : RuleBuilder

val a : Cell<int>

val b : Cell<int>

val sum : Cell<int>

val va : int

val vb : int

member Cell.Set : v:'T -> unit

val printfn : format:Printf.TextWriterFormat<'T> -> 'T

property Cell.Value: int with get

Raw view Test code New version

More information

Link:	http://fssnip.net/8aI
Posted:	28 days ago
Author:	Onur Gumus
Tags:	computation expressions