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 🙂