Josua Jäger JaggerJo

Fsharp goodies (Vol 1)

After the 'F# Compiler Community Session' I read the first 1K lines of SyntaxTree.fs. That's what I learned about the language.

There is a byte string

let a = "abc"B
val a : byte [] = [|97uy; 98uy; 99uy|]

Painless translations with F# and a bit of Magic.

A few weeks ago the unavoidable happened, a customer asked for a translated (non English) version of our SPA. We knew this would happen at some point, but as it happens always had more important work in our backlog.

There was no way to postpone this further.

Our requirements:

Translations can be outsourced/ done by non developers
Translations can be changed without releasing a new version

A 1000x improvement in performance

We recently had to provide (near) live data to a set of views in our application. After considering the most common ways to build this we decided to go with long polling. Our entire app is event based, so we know if a certain event happed the data might have changed. Lets assume the following types represent what can happen in our application:

type CounterEvent =
  | CounterWasIncremented byValue: int

	(* State *)
	type IState<'data> =
	abstract member Data: 'data
	abstract member Update: 'data -> unit

	[<CLIEvent>]
	abstract member Updated: IEvent<'data>

	(* Tracked State *)
	type ITrackedState<'data> =

	type OpenGLControl() as this =
	inherit Control()

	let mode = new Graphics.GraphicsMode(new Graphics.ColorFormat(8, 8, 8, 8), 24, 0, 0, Graphics.ColorFormat.Empty, 1);
	let mutable win : GameWindow = null

	do
	this.IsHitTestVisible <- false

	override this.OnAttachedToVisualTree args =

	module Observable =
	open System

	// ('a -> 'b -> unit) -> 'a -> IObservable<'b>
	let subscribeWeakly callback target source =

	let mutable sub:IDisposable = null
	let mutable disposed = false
	let wr = new WeakReference<_>(target)

	[<AutoOpen>]
	module NSImageExtensions =
	open AppKit

	type NSImage with

	static member GetSystemSymbolTinted (symbolName: string, accessibilityDescription: string, tint: NSColor) : NSImage =
	let original = NSImage.GetSystemSymbol(symbolName, accessibilityDescription)

	NSImage.ImageWithSize(original.Size, false, (fun bounds ->

	let editMenu =
	let undoMenuItem =
	let item = new NSMenuItem("Undo")
	item.KeyEquivalent <- "z"
	item.Action <- ObjCRuntime.Selector("undo:")
	item

	let redoMenuItem =
	let item = new NSMenuItem("Redo")
	item.KeyEquivalent <- "z"

	open Fable.React

	type private GlobalState =
	{\| current: Map<string, obj>
	update: Map<string, obj> -> unit \|}

	[<RequireQualifiedAccess>]
	module GlobalState =

	let private defaultValue =