Like most modern languages, F# comes with its own standard library. The F# library, however, comes in two parts:
implicitly referenced by every single F# application and is
the F# library. It contains the definitions for
common types such as
option, and so on.
The F# PowerPack is a set of experimental extensions and additional functionality meant to augment the F# library: for example, modules enabling F# applications to be source-level-compatible with the OCaml programming language.
Learning more about
FSharp.Core.dll will enable you to get the
most out of your F# projects. We’ve covered a lot of functionality in
the F# library throughout the book so far, but there are several gems
tucked away under the
Microsoft.FSharp namespace, the most useful of
which are a couple of purely functional (immutable) data
Chapter 4 introduced mutable
collection types as an easier-to-use alternative to
seq. However, if you want to strive for pure functional
programming, you can use functional collection types instead.
behave much like the
Dictionary<_,_> types from
Chapter 4, except that you cannot modify
any instance. So when you add a new element to the collection by using
Add method, rather than returning
unit and updating the internal data
structure, a new instance of the
Map<_,_> is returned instead.
Example A-13 uses the