Since you have done a significant amount of work with Haskell, I must presume you have a solid understanding of monads. If so, I can suggest reading http://stackoverflow.com/questions/2704652/monad-in-plain-english-for-the-oo... It is "for the OO programmer", but it does a good job of clarifying some issues. In particular, a "class hierarchy" is analogous to a stack of monads (made with monad transformers). That is to say, a class attaches 'methods' to an 'object' (i.e., a context, which might include data). Different languages use different monads to attach methods to objects -- for example, JavaScript uses "prototype-based" object orientation, which is very much analogous to the Haskell pattern: data SomeData = ... defaultData :: SomeData defaultData = ... setName :: Name -> SomeData -> SomeData setName = ... namedData :: SomeData namedData = setName (Name "Pete") defaultData Typically, an object oriented language provides an enriched IO monad which provides method dispatch based on context, state "for free" by setting variables (i.e., the dreaded side-effect), and so on. From a functional perspective, this is all syntactic sugar for a complicated monad transformer stack: type OO a = ClassT a (StateT a IO) a Typical object oriented languages are procedural in nature, and use explicit looping to handle iterating over data structures. Typically, all work is done in the same monad and it is "impossible" to define your own monads using "best practices" for that OO language. On Sun, Dec 30, 2012 at 11:58 AM, Daniel Díaz Casanueva < dhelta.diaz@gmail.com> wrote:
Hello, Haskell Cafe folks.
My programming life (which has started about 3-4 years ago) has always been in the functional paradigm. Eventually, I had to program in Pascal and Prolog for my University (where I learned Haskell). I also did some PHP, SQL and HTML while building some web sites, languages that I taught to myself. I have never had any contact with JavaScript though.
But all these languages were in my life as secondary languages, being Haskell my predominant preference. Haskell was the first programming language I learned, and subsequent languages never seemed so natural and worthwhile to me. In fact, every time I had to use another language, I created a combinator library in Haskell to write it (this was the reason that brought me to start with the HaTeX library). Of course, this practice wasn't always the best approach.
But, why I am writing this to you, haskellers?
Well, my curiosity is bringing me to learn a new general purpose programming language. Haskellers are frequently comparing Object-Oriented languages with Haskell itself, but I have never programmed in any OO-language! (perhaps this is an uncommon case) I thought it could be good to me (as a programmer) to learn C/C++. Many interesting courses (most of them) use these languages and I feel like limited for being a Haskell programmer. It looks like I have to learn imperative programming (with side effects all over around) in some point of my programming life.
So my questions for you all are:
* Is it really worthwhile for me to learn OO-programming?
* If so, where should I start? There are plenty of "functional programming for OO programmers" but I have never seen "OO programming for functional programmers".
* Is it true that learning other programming languages leads to a better use of your favorite programming language?
* Will I learn new programming strategies that I can use back in the Haskell world?
Thanks in advance for your kind responses, Daniel Díaz.
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