ExtCore is an extended core library for F#. ExtCore is designed to the same coding guidelines and quality standards as the F# core library (FSharp.Core), so the API is simple and intuitive to use.

ExtCore does not aim to be a "batteries-included" library; instead, ExtCore functionality is concentrated into a few key areas:

• Pervasives

  Top-level operators, functions, and modules providing common functionality. For example, the notImpl operator can be used to raise a System.NotImplementedException instead of the less-specific failwith, and the Option module provides additional functions for working with the 'T option type to complement those available in FSharp.Core's Option module.

• Collections

  Immutable data structures. Some of these are drop-in (almost) replacements for the Map and Set types in FSharp.Core which provide improved performance in specific scenarios (e.g., HashMap). Others provide unique functionality to help tackle specific coding tasks (e.g., LazyList and LruCache).

• Control

  Computation expressions (a.k.a. "workflows" or "monads") aimed at simplifying the implementation of common functional programming patterns. For example, ExtCore provides an asyncMaybe workflow which is similar to async in FSharp.Core but includes additional logic to handle cases where a computation encounters an error or fails to return a valid result.

• Control.Collections

  Modules which mirror the built-in collections modules in FSharp.Core like Array or Map, but whose functions are designed to work with the computation expressions included in ExtCore. For example, you might have some code that uses the Array.map function; if your mapping function can sometimes fail, you can use the Choice.Array.map function instead to gracefully handle the error instead of raising an exception.

Known bugs or other issues are listed on the ExtCore issues page.

ExtCore is licensed under the terms of the Apache 2.0 license.