F#: is there no UI (like WPF) for it?

Question

i recently saw some videos on F#. it seems it used mainly for Service or Classes only? i see no "F# WPF" app in VS2010 Beta?

Answer 1

F# actually has some very nice constructs for creating event-driven UI applications, such as First Class Events, Object Expressions, calling property setters from a constructor e.g.:

new Form(Text="My Window Title", Width=600, Height=400),

and much else.

However, creating a forms designer in VS reqiures a CodeDom for your language. The current CodeDom architecture works great, as long as your language looks exactly like C# or VB; it does not lend itself well to generation of F# code (this from a webcast or interview that I can't locate right now). It also requires partial classes, which if I recall correctly, are not supported in the language as of Beta 1. Rather than focus on designer support in the first release, the F# team decided to spend their resources on enhancing other parts of the language, such as asynchronous and parallel programming, etc.

What this means is that you have at least 4 choices for creating UI in F#:

• Write all UI code by hand, which is fine for simple apps;
• Create your F# code as a library to handle the "hard parts," like asynchronous and parallel code, or computation centric code, and call it from C#/VB;
• Create your UI code as a C#/VB library, and both drive it from F# and delegate event handling to F#; or
• Use a DSL or Computation Expression (monad) to simplify building the UI by hand (just discovered this while looking for other links in this answer).

Of these, calling a C# UI library from F# may be the most flexible while still retaining a familiar paradigm. But, using computation expressions for quickly building UI by hand is certainly worth looking at.