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New to f# need help
f#parsingfunctionaljava

hi everyone...so iv been racking my

brain trying to translate a couple of java functions that i wrote into F# and it

just isn't working for me...mainly cause im a begaining coder and iv never played with a functional language before...anyways i was wondering if theres anyone out there that

might be able to help explain F# in a way that actually makes sense in

my head...basically the functions i have written deal with parsing a

list, unions of 2 lists, intersects of 2 lists, and creating a power

set list out of a list....any help will be greatly appreciated...

heres what i got in java...

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public void union(Integer[] A, Integer[] B, Integer[] union_AB)
{
        for (int i=0; i<B.length; i++)
        {
                union_AB[i] = A[i] + B[i];
          }
}


//and
public void intersection ( int[] A, int[] B, int[] intersection_AB)
{
    for (int i =0; i< A.length; i++)
        {
            if ((A[i] == 1) && (B[i] == 1))
                intersection_AB[i]=1;
                else
                intersection_AB[i]=0;
         }
}
.

Hi Kane:

While zakaluka is teaching you to fish, I'll make lunch.

If you just want to use library functions, then the Set module provides the functionality you are looking for:

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#light
let a = Set.of_list [2;3;4]
let b = Set.of_list [3;4;5]
let union = a + b
let inter = Set.inter a b
printfn "Union = %A" union
printfn "Intersection = %A" inter

If, however, you are interested in writing these yourself, then see the good (free) O'Riley OCaml book at [link:caml.inria.fr] or pick up Robert Pickering's excellent book, which has great chapters on functional, imperative, and OO programming in F#. [link:www.amazon.com]

By on 10/15/2007 12:07 AM ()

I recently discovered that you can actually create a set with only:

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set [1;2;3]

Very cool! :-)

By on 10/19/2007 1:11 PM ()

Well, if I didn't know better, I'd say this is a classic homework assignment for any elementary Programming Languages class.

As such, I only offer 1 hint: make use of F#'s built-in looping operators over lists (map, fold, etc). They'll reduce the majority of the functions you have to 1-liners.

Regards,

Z.

By on 10/14/2007 10:49 PM ()

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