B# .NET Blog

Introduced in my previous blog post on The Essence of LINQ – MinLINQ, the first release of this project is now available for reference at the LINQSQO CodePlex website at http://linqsqo.codeplex.com. Compared to the write-up over here in my previous post, there are a few small differences and caveats:

• Only FEnumerable functionality is available currently; the FObservable dual may follow later.
• Option<T> has been renamed to Maybe<T>, to be CLS compliant and avoid clashes with the VB keyword.
• Some operators are not provided, in particular GroupBy, GroupJoin and Join. They’re left as an exercise.
• A few operator implementations are categorized as “cheaters” since they roundtrip through System.Linq.
• Don’t nag about performance. The MinLINQ code base is by no means optimal and so be it.
• Very few System.Interactive operators are included since those often require extra foundations (such as concurrency).

A few highlights:

• FEnumerable.Essentials.cs is where the fun starts. Here the three primitives – Ana, Bind and Cata – form the ABC of LINQ.
• There’s a Naturals() constructor function generating an infinite sequence of natural numbers, used in operators that use indexes.
• OrderBy and ThenBy are supported through roundtripping to System.Linq with a handy trick to keep track of IOrderedEnumerable<T>.
• As a sample, I’ve included Luke Hoban’s LINQified RayTracer with AsFEnumerable and AsEnumerable roundtripping. It works just fine.
• Creating an architectural diagram in Visual Studio 2010 yields the following result (not meant to zoomed in), where I’ve used the following colors:
• Green = Ana
• Blue = Bind
• Red = Cata

Obviously, all sorts of warnings apply. People familiar to my blog adventures will know this already, but just in case:

//
// This project is meant as an illustration of how an academically satifying layering
// of a LINQ to Objects implementation can be realized using monadic concepts and only
// three primitives: anamorphism, bind and catamorphism.
//
// The code in this project is not meant to be used in production and no guarantees are
// made about its functionality. Use it for academic stimulation purposes only. To use
// LINQ for real, use System.Linq in .NET 3.5 or higher.
//
// All of the source code may be used in presentations of LINQ or for other educational
// purposes, but references to http://www.codeplex.com/LINQSQO and the blog post referred
// to above - "The Essence of LINQ - MinLINQ" - are required.
//

Either way, if you find LINQ interesting and can stand some “brain pain of the highest quality” (a Twitter quote by dahlbyk), this will likely be something for you.