[Haskell-cafe] using haskell for a project

[Nicolas Martyanoff]

Hi,

I don't think I already presented myself; I'm Nicolas, a 23y french
student, trying to learn and use haskell.

I've been using C for years, for all sort of tasks, and am quite
comfortable with it. I'm also using it 40h a week in my internship for
network systems, so I kind of know how to use it.

I discovered Haskell some monthes ago, bought `Real World Haskell',
quickly read, and enjoyed it.

So now I'd want to use it for a small project of mine, a simple
multiplayer roguelike based on telnet. I wrote a minimal server in C, and
it took me a few hours. Now I'm thinking about doing the same in Haskell,
and I'm in trouble.

I don't really know how to map my ideas in haskell code. For example, a
character can cast spells, so I'd have something like this in C:

    struct hashtable spells;

    struct character {
        int n_spells;
        struct spell **spells;
    };

I thought I could do something like this in haskell:

    spells = Data.Map.Map Int Spell

    data Character = Character { charSpells :: [Int] }

But now I don't know how to dynamically add new spells (new spells can be
created in my gameplay). Since I can't assign a new value to the `spells'
variable (Data.Map.insert returns a new map), I just don't know where to
go.

I have the same problem for a bout every problem. I love writing pure
functions in haskell, but as soon as I try to write some code involving
states or side effects, I can't write a line.

I just wanted a 2d array to store a zone, for example, dead simple in C,
but this kind of link
http://greenokapi.net/blog/2009/03/10/rough-grids-in-haskell make me
shiver.

Point is, I'd like to use haskell, but I don't know how, it seems totally
alien.

How did you manage to change the way you map ideas to code, from
imperative to pure functional ?

Thank you.

Regards,

-- 
Nicolas Martyanoff
   http://codemore.org
   khaelin at gmail.com
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