I have been learning F# recently, and one of the great things about it is the REPL, called F# Interactive.
I ran into a problem when I tried to reference the
NuGet package in an
.fsx file, like so:
#I @"C:\Users\Jon\.nuget\packages\" #r @"Newtonsoft.Json\11.0.2\lib\netstandard2.0\Newtonsoft.Json.dll"
Those lines give no indication of any potential problems, but when I try to use
JsonConvert.DeserializeObject to deserialize a
JSON string, I get an ugly red squiggly with the following error message:
The type ‘Object’ is required here and is unavailable. You must add a reference to assembly ‘netstandard, Version=188.8.131.52, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51’.
Oh my. What to do?
I poked around a little bit on Google and Stack Overflow, but didn’t really find an easy fix, so I set out to find
netstandard.dll on my local machine. After a few false starts, I just did an Explorer search in
netstandard.dll and picked the most promising result.
I shift-right-clicked on the file to get the path and added it to my references in the
#I @"C:\Users\Jon\.nuget\packages\" #r @"Microsoft.NETCore.App\2.1.0-rtm-26502-02\ref\netcoreapp2.1\netstandard.dll" #r @"Newtonsoft.Json\11.0.2\lib\netstandard2.0\Newtonsoft.Json.dll"
And voilà! The ugly red squiggly disappeared, and my script ran correctly in
If you know of a more elegant solution, please contact me on Twitter (@jonsagara) and I’ll update this post.
I’ve heard rumors that the F# team will make it easier to reference NuGet packages in future versions of
FSI. I can’t wait!
Visual Studio 2017, 15.7.4 F# Interactive version 10.1.0 for F# 4.1 Newtonsoft.Json 11.0.2 .NET Standard 2.0 .NET Core 2.1