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Implicit/Explicit Conversions
f#

I'm trying to define a structure type which can be implicitly (or explicitly) converted to an int. Why doesn't the following code work? (Maybe I'm not understanding the docs correctly).

type EvenRoll =

struct

val value: int

new(x) = { value = let rec loop a =

if IsEven a then a else loop(RandomDieRoll())

loop x }

static member op_Implicit(e:EvenRoll) : int = e.value

static member op_Explicit(e:EvenRoll) : int = e.value

end

let x:int = int(EvenRoll(0))

I get 'The type 'EvenRoll' does not support a conversion to type 'int''.

.

Define op_Implicit, or op_Explicit, but not both. The diagnostic is bad here, but that's the problem. Comment either one out and it works.

By on 11/6/2010 1:12 PM ()

Hi,

the int conversion operator works with predefined primitive types, but the type you defined already supports conversion to int:

let x = EvenRoll 0

let x1 = x |> EvenRoll.op_Explicit

or:

let x2 = x.value

I Hope this is the answer you're looking for, regards Taha.

By on 11/6/2010 10:40 AM ()

Okay. But what's the point of defining op_Implicit or op_Explicit for a user type? Couldn't you just define any arbitrary member that does this, since you have to call it explicitly anyway?

By on 11/6/2010 10:48 AM ()

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