Top 20 NuGet functional Packages

Lightweight library with basic types of functional-programming style
Unified Utility Library Underscore.cs
Maybe/Optional monad implementation for C#. For more information see http://csharp-functional.readthedocs.io/en/latest/maybe-monad.html.
Package Description
Minimal template for using Fable 2.1
Core for building domain-driven, functional and event-based applications.
Revolutionize your MVVM. Compose and connect properties, reuse property patterns, and make your presentation logic code concise, predictable, and less error-prone. Make your async VMs portable.
The Reactive Extensions for C++ (RxCpp) is a library of algorithms for values-distributed-in-time. The Range-v3 library does the same for values-distributed-in-space. Compiles for gcc, clang and VisualStudio on Linux, OSX and Windows.
Functional primitives for Unity3D - inspired by csharp-monads, Haskell & F#
Extension methods and other objects for integrating the Optional# Optional type into .NET.
A Freya Router based on URI Templates for route matching
An extension to the Freya HTTP Machine adding Patch support
An extension to the Freya HTTP Machine adding CORS support
Extensions that support the C# functional paradigm, focusing mainly on infinite enumerables.
Alternative routing API for Giraffe web applications which is aimed at maximum performance.
An implementation of the Tcl scripting language. This package contains the MSBuild tasks and PowerShell cmdlets that enable integration [with Eagle] as well as the command-line shell [for Eagle].
An implementation of the Tcl scripting language. This package contains the MSBuild tasks and PowerShell cmdlets that enable integration [with Eagle] as well as the command-line shell [for Eagle].
A collection of useful types and operations specialized for errors.
An implementation of the Tcl scripting language.
JSON serialization capabilites for Tiger Types.