use c# library in f#

Question

I am trying to connect to Interactive Brokers via their C# API. As an exercise, I am trying to develop my client in F#.

This is what I have done:

1. I have imported the CSharpAPI project in Visual Studio. CSharpAPI defines the IBApi namespace
2. I have created a new F# project in the solution. The project will host my implementation

3. I created a new module in a .fs file as below:

   open IBApi
   
   module ibConnectivity =
   
      type IBclient =
          interface EWrapper with
          member this.connectionClosed() = printfn "connection has been closed"
          member this.currentTime time = printfn "server time: %i" time
   ....
   

I get the following error message:

Error 1 Files in libraries or multiple-file applications must begin with a namespace or module declaration, e.g. 'namespace SomeNamespace.SubNamespace' or 'module SomeNamespace.SomeModule'

I have googled around for a solution. I am a complete noob. Some posts refer to F# file order, but in this case I am working with a C# library.

Answer 1

This means that your file must start with a namespace or module declaration. Like this:

module ibConnectivity

open IBApi

type IBclient =
    interface EWrapper with
    member this.connectionClosed() = printfn "connection has been closed"
    member this.currentTime time = printfn "server time: %i" time

The syntax module Name = <indented declarations> is used to declare sub-modules within the module or namespace declared at the top of the file.