An implementation of file or module '{0}' has already been given. Compilation order is significant in F# because of type ...

An implementation of file or module '{0}' has already been given. Compilation order is significant in F# because of type inference. You may need to adjust the order of your files to place the signature file before the implementation. In Visual Studio files are type-checked in the order they appear in the project file, which can be edited manually or adjusted using the solution explorer.