Hacking referenced assemblies

Question

I am aware that there are already other questions on the topic, such as:

• This one
• This one
• This other one

.. but hey, I am new to F# and still don't get it.

I have a F# project (thelibrary) which contains some modules. This project references in the solution explorer all the necessary libraries. Each .fs file opens the libraries used in the module. The F# project compiles properly.

I have then another F# project which contains a script. I reference thelibrary and the libraries used by thelibrary itself. In the script I reference with #r the dll with thelibrary and all the libraries used by thelibrary. I then open all the modules. Intellisense says all is allright until I execute the script.

The script returns the error:

error FS0074: The type referenced through 'Fmat.Numerics.Matrix`2' is defined in an assembly that is not referenced. You must add a reference to assembly 'Fmat.Numerics'.

What is the procedure to hack this problem? How do I proceed from there? I am interested is a solution to this specific problem but, as well, a cookbook recipe to fix this type of issues that have been quite a source of frustration for me.

Thank you.

Answer 1

The behavior of F# Interactive can be a bit odd in this case. In general, I think that things work better when you use #I to include the path with referenced assemblies in the resolution context and then reference the libraries by name using #r. So if you have a library Fmat.Numerics.dll in a folder C:\libs and it references another library another.dll then you can do:

#I "C:\\libs"
#r "another.dll"
#r "Fmat.Numerics.dll`

The first line means that F# Interactive will automatically look in the folder with your libraries (this can be relative path to your script location too) - as a result, the next two lines can just reference the libraries by their file names.

Answer 2

Running things in fsi does not add references from the project, you need to use #r .... The error message is reasonably obvious in what you need to do - add a reference to Fmat.Numerics. It is also possible that you have such a reference, but that fsi is sensitive to the load order.

Answer 3

This is still a problem. I can also reproduce and fix the problem as follows:

I have three projects:

1. Informedica.Settings.Library
2. Informedica.Settings.Services.Interfaces
3. Informedica.Settings.Services.Models

Project 2 uses project 1 and project 3. Project 1 uses project 3.

When I load the references in the order (first proj 3 then proj 1):

#r @"..\..\Informedica.Settings.Services.Models\bin\Release\Informedica.Settings.Services.Models.dll"
#r @"..\..\Informedica.Settings.Library\bin\Release\Informedica.Settings.Library.dll"

Everything works. Unfortunately, when I use the VS2013 send references to fsi or use the new power tools generate references option, the order is:

#r @"..\..\Informedica.Settings.Library\bin\Release\Informedica.Settings.Library.dll"
#r @"..\..\Informedica.Settings.Services.Models\bin\Release\Informedica.Settings.Services.Models.dll"

This will result in the FS0074 error. Apparently, because a type from Services.Models is used in Settings.Library and the order of reference is reversed, fsi cannot handle this. Correcting the order of referencing solves the problem.