Chaining Side Effects in F# (and WPF DependencyProperty as a Special Case)

The first question that any functional programmer should ask is, “why are there side effects?!” Side effects are anathema to functional programming purists because they introduce many kinds of undesirable characteristics into code, limiting optimisation and restructuring options. However, most object-oriented libraries, including the .NET BCL, depend on side effects and many of these are intrinsic to writing .NET applications.

WPF is a special case where this applies, with DependencyProperty fields.

Creating WPF Dependency Properties in F#

This is a quick post demonstrating how to create WPF Dependency Properties in F#. There is a bit of a trick to it as you have to use the val keyword to define a field and that field must be mutable and you also have to use explicit interface access.