How can a cacheline sized struct wrapping a mutable, volatile int64 be created in F#? -

i want create cacheline sized struct wrapping mutable, volatile int64 in f#. i’ve tried various struct definitions including 1 below, can't compile.

[<struct; structlayout(layoutkind.explicit, size = 64)>] type mystruct1 (initval:int64) =     [<volatilefield>]     let mutable value = initval     member x.value          () = value         , set(valin) = value <- valin 

which gives error: "structs cannot contain value definitions because default constructor structs not execute these bindings. consider adding additional arguments primary constructor type". can't see additional arguements add primary constructor above.

any ideas?

the struct definition be

[<struct; structlayout(layoutkind.explicit, size = 64)>] type mystruct =     [<fieldoffset(0)>]     val mutable value : int64     new(initval:int64) = { value = initval }     member x.value         get() = x.value         , set(valin) = x.value <- valin 

but then, [<volatilefield>] not allowed on val bindings , structs can't contain let bindings.

tl;dr: afaik this impossible in f#

as pointed out @v.b. use interlocked gives superset of volatiles guarantees (stronger guarantees ≈ more overhead). might better privateize value prevent (accidental) writes circumventing barrier:

[<struct; structlayout(layoutkind.explicit, size = 64)>] type mystruct =     [<fieldoffset(0)>]     val mutable private value : int64     new(initval:int64) = { value = initval }     member public x.value         get() = interlocked.read(&x.value)         , set(valin) = interlocked.exchange(&x.value, valin) |> ignore