Hi,

I used Helium(subsetlanguage of Haskell) in the past few months and I think it's working better dan C++(especially because there's a lot to know about C++, before you really "know" C++).

The same can be said about Haskell, too :).

need some speed(code can't be more than 1.5 times slower than C++). And I want to use large array's(>60000 elements) where each element had an type in it with another 5 elements.

You will need to use stateful, mutable arrays, which means you need to know about monads, at least the IO monad.

data Thing=ConFunction Int Int Int Int Int Thus an array of Thing.

This wouldn't be a problem. Using clever instance declarations, you could even "under the hood" represent this by five unboxed arrays, which will give you speed and good memory usage, at the expense of laziness.

I want to use Haskell for creating a GUI. Furtermore I I use Windows 98 Se (It seems that some libs. are only for UNIX.)

This is going to be your biggest hurdle (the GUI). I don't know how well along the port for ObjectIO is, but probably your best bet is going to be GTK, which is pretty well supported in Haskell, but I don't know about in Windows (I believe it works, though). You could also use Tk, but this is kind of ugly (though it's easy and well supported) and lacks some modern controls.

Is it usefull for me to use Haskell, are there enough libraries so I can easily recreate and improve my program?

Perhaps, perhaps not. I'd say it depends how well you know Haskell. - Hal