Question

I’m just getting started off with F#, so there could be something very simple that I’m missing, but I’m getting a compiler error that no one seems to have run into:

The signature file ‘AsyncSocket’ does not have a corresponding
implementation file. If an implementation file exists then check the
‘module’ and ‘namespace’ declarations in the signature and
implementation files match.

I thought it could be something wrong with my code, so I copied the example from msdn and I’m getting the exact same thing. Any idea what’s happening?

Signature:

namespace Library1
  module Module1 = 
    val function1 : int -> int
    type Type1 =
        new : unit -> Type1
        member method1 : unit -> unit
        member method2 : unit -> unit

    [<Sealed>]
    type Type2 = 
        new : unit -> Type2
        member method1 : unit -> unit
        member method2 : unit -> unit

    [<Interface>]
    type InterfaceType1 =  
        abstract member method1 : int -> int
        abstract member method2 : string -> unit

Implementation:

namespace Library1
module Module1 =

    let function1 x = x + 1

    type Type1() =
        member type1.method1() =
            printfn "test1.method1" 
        member type1.method2() =
            printfn "test1.method2"


    [<Sealed>]
    type Type2() =
        member type2.method1() =
            printfn "test1.method1" 
        member type1.method2() =
            printfn "test1.method2"

    [<Interface>]
    type InterfaceType1 =
        abstract member method1 : int -> int
        abstract member method2 : string -> unit

Answer 1

This error occurs if the signature and implementation files have different names (sans extensions). The signatures and implementations should be in separate files named <same-name>.fsi and <same-name>.fs, respectively. As pad commented, the signature file should immediately precede the implementation file in the build order (or Solution Explorer treeview).