F# compilation error in Linqpad 7 when trying to use FSharp.Data packages

costa

Hi,

On my computer I have .Net SDK 3.1 & .Net SDK 5.0. I am using Windows 2016. Linqpad version: 7.1.5. Other info:

Host runtime version: 5.0.12
Default query runtime version: 5.0.12
Default query reference assembly version: 5.0.0
Roslyn Version: 4.0.1-1.21558.15
FSharp.Compiler.Service version: 41.0.1.0
NuGet client version: 5.11.0.10
Results rendering engine: Microsoft WebBrowser 11

I created a new query with type F# Program:

<Query Kind="FSharpProgram">
  <NuGetReference>FSharp.Data.SqlClient</NuGetReference>
  <Namespace>FSharp.Data.SqlClient</Namespace>
</Query>

[<Literal>]
let compileTimeCn = 
    @"Data Source=MyServer;Initial Catalog=MyDb;Integrated Security=True"

use cmd = new SqlCommandProvider<"SELECT * from dbo.SomeTable" , compileTimeCn>(compileTimeCn)
let data = cmd.Execute() 

When I compile this I get:

The type provider 'C:\Users\xyz\.nuget\packages\FSharp.Data.SqlClient\2.0.7\lib\netstandard2.0\FSharp.Data.SqlClient.dll' reported an error: The type provider designer assembly 'FSharp.Data.SqlClient.DesignTime.dll' could not be loaded from folder 'C:\Users\xyz\.nuget\packages\FSharp.Data.SqlClient\2.0.7\lib\typeproviders\fsharp41\netstandard2.0'. The exception reported was: System.IO.FileNotFoundException - Could not load file or assembly 'FSharp.Core, Version=4.4.3.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'. The system cannot find the file specified.

I also got a similar error when I tried to add the FSharp.Data package to read CSV files:
The type provider 'C:\Users\xyz\.nuget\packages\FSharp.Data\4.2.6\lib\netstandard2.0\FSharp.Data.dll' reported an error: The type provider designer assembly 'FSharp.Data.DesignTime' could not be loaded from folder 'C:\Users\xyz\.nuget\packages\FSharp.Data\4.2.6\typeproviders\fsharp41\netstandard2.0'. The exception reported was: System.IO.FileNotFoundException - Could not load file or assembly 'FSharp.Core, Version=4.7.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'. The system cannot find the file specified.

Any idea on how to fix this? Linqpad seems to have a problem with the F# type providers.

As a side note, in VS2019 I don't have these issues.

Thanks

costa

In Linqpad 6 I get a different error:

The type provider 'FSharp.Data.SqlCommandProvider' reported an error: Could not load file or assembly 'System.Data.SqlClient, Version=4.4.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'. Reference assemblies should not be loaded for execution. They can only be loaded in the Reflection-only loader context. (0x80131058)

I added the reference to System.Data.SqlClient but it still gives the above error. So, I am not too sure what's going on here.

JoeAlbahari

Have you tried the latest LINQPad 7 beta?
https://www.linqpad.net/linqpad7.aspx#beta

costa

I am still getting an error in the beta version.

The type provider 'FSharp.Data.SqlCommandProvider' reported an error: Could not load file or assembly 'System.Data.SqlClient, Version=4.4.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'. Reference assemblies should not be loaded for execution. They can only be loaded in the Reflection-only loader context. (0x80131058)

<Query Kind="FSharpProgram">
  <NuGetReference>FSharp.Data.SqlClient</NuGetReference>
  <NuGetReference>Microsoft.Data.SqlClient</NuGetReference>
  <NuGetReference>System.Data.SqlClient</NuGetReference>
  <Namespace>FSharp.Data</Namespace>
  <Namespace>FSharp.Data.SqlClient</Namespace>
  <RuntimeVersion>6.0</RuntimeVersion>
</Query>

[<Literal>]
let compileTimeCn = 
    @"Data Source=db_server;Initial Catalog=db;Integrated Security=True"

use cmd = new SqlCommandProvider<"SELECT * from dbo.SomeTable" , compileTimeCn>(compileTimeCn)
let data = cmd.Execute() 

JoeAlbahari

Looks like it could be this issue:
https://github.com/fsprojects/FSharp.Data.SqlClient/issues/373

Fundamentally, it's a difficult problem to solve in .NET Core. Without application domains, resolving and loading arbitrary assemblies into the host (and unloading them again) is inherently hacky and unreliable.