The declarations in this file will be placed in an implicit module '{0}' based on the file name '{1}'. However this is not ...

The declarations in this file will be placed in an implicit module '{0}' based on the file name '{1}'. However this is not a valid F# identifier, so the contents will not be accessible from other files. Consider renaming the file or adding a 'module' or 'namespace' declaration at the top of the file.