Using f# on a mac with the dotnet cli

Question

I was trying to follow https://github.com/enricosada/fsharp-dotnet-cli-samples/wiki/Getting-Started#hello-world to get started with f# and dotnet core on my mac.

% mkdir helloworld
% cd helloworld
% dotnet new --lang "f#"
Created new F# project in /Users/User/dotnet/helloworld.
% ls
Program.fs   project.json

Here, I can already tell, that there is no NuGet.Config as outlined in the tutorial I followed. Then

% dotnet restore
log  : Restoring packages for /Users/User/dotnet/helloworld/project.json...
log  : Restoring packages for tool 'dotnet-compile-fsc' in /Users/User/dotnet/helloworld/project.json...
log  : Writing lock file to disk. Path: /Users/User/dotnet/helloworld/project.lock.json
log  : /Users/User/dotnet/helloworld/project.json
log  : Restore completed in 2148ms.
% dotnet run
Project helloworld (.NETCoreApp,Version=v1.1) will be compiled because expected outputs are missing
Compiling helloworld for .NETCoreApp,Version=v1.1
The specified framework 'Microsoft.NETCore.App', version '1.0.0' was not found.
  - Check application dependencies and target a framework version installed at:
      /usr/local/share/dotnet/shared/Microsoft.NETCore.App
  - The following versions are installed:
      1.1.0
  - Alternatively, install the framework version '1.0.0'.
/usr/local/share/dotnet/dotnet compile-fsc @/Users/User/dotnet/helloworld/obj/Debug/netcoreapp1.1/dotnet-compile.rsp returned Exit Code 131

Compilation failed.
    0 Warning(s)
    0 Error(s)

Time elapsed 00:00:00.4439997

Dotnet info says

% dotnet --info
.NET Command Line Tools (1.0.0-preview2-1-003177)

Product Information:
 Version:            1.0.0-preview2-1-003177
 Commit SHA-1 hash:  a2df9c2576

Runtime Environment:
 OS Name:     Mac OS X
 OS Version:  10.12
 OS Platform: Darwin
 RID:         osx.10.12-x64

Those instructions mention (at the top) installing the .Net Core Preview 1. But https://github.com/dotnet/cli/releases lists Preview 3, whose [release announcement](https://blogs.msdn.microsoft.com/dotnet/2016/11/16/announcing-net-core-tools-msbuild-alpha/) mentions that they're moving away from `project.json` and back to a `.csproj` format, though it's a `.csproj` format that's apparently greatly simplified from what it used to look like. Perhaps you simply need to update your .NET CLI tools to 1.0 preview 3 and try again? — rmunn, Nov 25 '16 at 07:48

score 2 · Answer 1 · answered Jan 09 '17 at 22:49

I had a similar issue before when creating the F# project using dotnet new --lang "f#"

The problem is this dependency, which you should see in you project.json file: dotnet-compile-fsc.

"tools": {
    "dotnet-compile-fsc": "1.0.0-preview2.1-*"
},

At the time of writing this only supports the .Net Core 1.0.* runtime, not the .Net Core 1.1.* runtime you have installed.

To fix this you can install the .Net Core 1.0.* runtime from here and run dotnet run again. Both the 1.1.* and 1.0.* runtimes can be installed locally without issue.

For reference, here is the issue reported on GitHub. There is a fix but it's not on NuGet yet.

score 1 · Answer 2 · answered Jan 16 '17 at 12:54

The current dotnet-compile-fsc doesnt work yet with .NET Core 1.1 (current, sdk preview2.1), only with .NET Core 1.0 (LTS, sdk preview2).

You can workaround doing the dotnet restore like the following, using the dev feed because the new package is not yet on nuget.org

dotnet restore -f https://www.myget.org/F/netcorecli-fsc-preview2-1/api/v3/index.json

see https://github.com/dotnet/netcorecli-fsc/wiki/.NET-Core-SDK-preview2.1 for more info/workaround

Using f# on a mac with the dotnet cli

2 Answers2