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Quotations and byref functions
f#

I'd like to use atomic ops in functions marked as reflected definition. Unfortunately it doesn't compile and I have this error:<i>"Quotations cannot contain this kind of type"<i>. <code lang=fsharp> open System open System.Threading [<ReflectedDefinition>] let myFunc (i:int) (a:int[]) = Interlocked.Add(&(a.[ i ]), 7) |> ignore let main () = let myArray = [|0 .. 19|] myFunc 5 myArray do main () </code> This seems to be cause by usage of an <i>address-of<i> expression in a reflected definition. If I try to write this, compilation failed too with the same error message but more accurately placed under "loc": <code lang=fsharp> [<ReflectedDefinition>] let addWithByRef (loc : int byref) (value:int) = loc <- loc + value let main () = let myArray = [|0 .. 19|] addWithByRef (&myArray.[ 5 ]) 7 do main () </code> Thanks!

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I'm afraid this is a limitation of F# quotations (there are a couple of others), that you can't do much about. It seems that it's just not possible to use 'byref' types in the quoted code. I'd probably write my own function that encapsulates Interlocked.Add without using 'byref' types and then call this function from the quoted code (your quotation analyzer can easily deal with one additional 'special' function). Something like this:

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open System
open System.Threading

let interlockedAdd (a:int[]) i n = 
  Interlocked.Add(&(a.[ i ]), n) |> ignore
  
[<ReflectedDefinition>]
let myFunc (i:int) (a:int[]) = interlockedAdd a i 7
By on 2/3/2010 3:25 PM ()

Thanks Tomas. It does the trick pretty nicely.

By on 2/3/2010 4:28 PM ()

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