This chapter covers simple interactive programming with F# and .NET. To begin, you should download and install a version of the F# distribution from
www.fsharp.net. You may also have a version on your machine already. The sections that follow use F# Interactive, a tool you can use to execute fragments of F# code interactively and a convenient way to explore the language. Along the way, you see examples of the most important F# language constructs and many important libraries.
Listing 2-1 shows your first complete F# program. You may not follow it all at first glance, but we explain it piece by piece after the listing.
Example 2.1. Analyzing a String for Duplicate Words