// Learn more about F# at http://fsharp.net
// See the 'F# Tutorial' project for more help.
let rec NWD = function
    | (0, n) -> n
    | (m, n) -> NWD(n % m, m)

let skroc (l,m) =
    let znak = if l*m<0 then -1 else 1
    let al = abs l
    let am = abs m
    let d  = NWD(al,am)
    in (znak * (al / d), am / d)

let naString (l, m) =
    let znak = if l*m<0 then "-" else "" (* deklaracje wewnetrzne
*)
    let al = abs l                  (* wart.bezw. = liczba nat.
*)
    let am = abs m
    let d = NWD(al, am)
    in znak + (System.Convert.ToString(al / d))
           + "/" + (System.Convert.ToString(am / d))

[<EntryPoint>]
let main argv =
    let ( ++ ) (a, b) (c, d) = (a*d + b*c, b*d)
    let ( -- ) (a, b) (c, d) = (a*d - b*c, b*d)
    let ( ** ) (a, b) (c, d) = (a*c, b*d)
    let ( /./ ) (a, b) (c, d) = (a,b) ** (d,c)
    let ( == ) (a, b)  (c, d) = (a*d = b*c)

    let a= (1,2) ++ (2,3)
    let b =  1./2. + 2./3. * 3./4.
    let c = (1, 2) ++ (2, 3) ** (3, 4)
    printfn "pierwsze %A" a
    printfn "drugie %A" b
    printfn "trzecie %A" c
    let q1 = (-2, 3);
    let q2 = (5, -10);
    let q3 = q1 ++ q2
    let q3_1 = q1 -- q2
    let q4 = q2 **q3
    let q5 = q4 /./ q3
    let q5_1 = q1 == q2
    let ns1 = naString q4
    let ns2 = naString q5

    printfn "q1= %A" q1
    printfn "q2= %A" q2
    printfn "q3= %A" q3
    printfn "q31= %A" q3_1
    printfn "q4= %A" q4
    printfn "q5= %A" q5
    printfn "q51= %A" q5_1
    printfn "ns1= %A" ns1
    printfn "ns2= %A" ns2

    0 // return an integer exit code