A C# library to write functional code - Part I - Background

Other posts in the se­ries:

• Part I - Background

  • Part II - Tuples

    • Part III - Records
    • Part IV - Type Unions{.}
    • Part V - The Match operator{.} In December (slow time in msft) I decided to understand what functional programming is all about. When I say ‘understanding’ I don’t mean just paying lip service to the main concepts by knowingly mentioning them in casual conversations (i.e. look at this memoization, man! or this lambda function is so hot!. I can already do that. I intellectually know what the thing is.

    I wanted to *really* un­der­stand it. For me that means writ­ing plenty of code. I had a medium size ap­pli­ca­tion in my mind that I’ve been want­ing to write for quite some time (stock price, div­i­dends, splits down­load­ing and var­i­ous re­turn cal­cu­la­tions), so I went ahead and wrote it. I also wanted to use C#. It would have been eas­ier in F#, but I work on the C# team and love us­ing our own prod­uct.

    My early at­tempts were un­pleas­ing. I would fall back to my OO back­ground and my func­tional code slowly re­verted to OO code. My way of think­ing about it, even if start­ing with the best in­ten­tions, would go back to: what are the ob­jects, what are their re­spon­si­bil­i­ties and such.

    I needed to force my­self some­how; kind of over­com­pen­sate on the other side. I hit on the idea of prag­mat­i­cally defin­ing func­tional pro­gram­ming and try to limit my­self to the sub­set of lan­guage con­structs in­side my de­f­i­n­i­tion. As a way to de­fine it, I used Chapter 3 of Expert F#. I know, I know, I could have read 1,000s of aca­d­e­mic pa­pers and come up with a meta-analy­sis of all of them that for­mally de­fines what ‘functional pro­gram­ming’ re­ally is. But life is too short. I trusted Don.

    The prob­lem is, sev­eral of the lan­guage con­structs in my small de­f­i­n­i­tion of func­tional pro­gram­ming don’t ex­ist in C#. So I went ahead and cre­ated them. I built a lit­tle li­brary to rep­re­sent them and forced my­self to write code us­ing just this li­brary. It worked.

    In this se­ries of posts I will de­scribe what’s in­side this li­brary. I want to em­pha­size that I built it for ed­u­ca­tional pur­pose only, not for per­for­mance or pro­duc­tion code. Caveat emp­tor.

    My plan is to cover the fol­low­ing:

    1. Tuples
       • Records
         • Type Unions
           • Match
    Let’s see if I can find the time to actually write these posts 🙂

Tags

• CSHARP

15 Comments

Comments

Jacob

2008-04-01T15:36:07Z

Sounds in­ter­est­ing! I re­ally hope this is­n’t some sub­tle April fool’s joke.

lucabol

2008-04-01T15:40:29Z

Nope.
But I should have thought of one :)

Nair

2008-04-02T13:01:04Z

Please do, can’t wait to read. I am a C# pro­gram­mer as well and love the lan­guage and re­cently I have started read­ing Robert’s book on F# fun­da­men­tals. It is good, but some­times it just goes over my head. I did­n’t get the “Expert F#”. I was kind of in­tim­i­dated by the name.

lucabol

2008-04-02T13:49:46Z

“Expert F#” is a fan­tas­tic book as a func­tional/​OO bridge. Don’t mind the “Expert” tag.
Also the up­com­ing “F# for sci­en­tists” is re­ally good to show prac­ti­cal ap­pli­ca­tions of it.
I sug­gest you get them both.

Luca Bolognese's WebLog

2008-04-08T17:06:24Z

Previous posts: Part I - Background Tuples are a way for you not to name things. In Object Oriented lan­guages

NN

2008-04-12T06:25:56Z

About pat­tern match.
Here: http://​rsdn.ru/​fo­rum/​mes­sage/​2783992.1.aspx, you have some ex­am­ple of pat­tern match­ing in C#
Source code:
http://​files.rsdn.ru/​27808/​CSharp­Pat­tern­Match­ing.zip

Luca Bolognese's WebLog

2008-04-21T13:35:41Z

Previous posts: Part I - Background Part II - Tuples Now that we know what Tuples are, we can start talk­ing

Charlie Calvert's Community Bl

2008-04-23T16:58:14Z

Welcome to the forty-third is­sue of Community Convergence. The last few weeks have been con­sumed by the

Frank Quednau

2008-04-28T11:26:58Z

Hm,
as to the pat­tern match­ing: Bart De Smet has done a great job on de­vel­op­ing pat­tern match beauty. I link you to his April archive, where most of his work is done:
http://​com­mu­nity.bart­desmet.net/​blogs/​bart/​archive/​2008/​04.aspx
Myself, I have worked on a func­tion com­po­si­tion in­fra­struc­ture in­spired by Haskell’s ‘dot’ op­er­a­tor: http://​re­al­fic­tion.net/?​q=node/​118
Enjoy!

lucabol

2008-04-28T13:00:01Z

This is very good stuff. My thing is much sim­pler.
Thanks for the link.

ABDULLAH MOHAMMED SALEH ALHEMY

2008-05-01T12:32:24Z

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ABDULLAH MOHAMMED SALEH ALHEMY

2008-05-01T12:58:57Z

MY NAME  :ABDULLAH MOHAMMED SALEH ALHEMYARI            / BANK ACCOUNT name:IN­TER­NA­TIONAL BANK OF YEMEN /  BRANCH: ZUBAIRY  /swift:IBOYYESAXXX  /ACCOUNT no:A/​C#:0002-186557-002′/​my E-MAIL ADDRESS: BNAFIF88@hotmail.com/COUNTRY :YEMEN

adamjcooper.com/blog

2008-06-03T15:38:15Z

The Quest for Quick-and-Easy Class-Based Immutable Value Objects in C# - Part 1: Introduction

adamjcooper.com/blog

2008-06-03T16:58:29Z

The Quest for Quick-and-Easy Immutable Value Objects in C#

Luca Bolognese's WebLog

2008-07-15T05:46:23Z

Other posts in the se­ries: Part I - Background Part II - Tuples Part III - Records Part IV - Type Unions