NixOS, VS Code and Haskell-related extensions for VS Code

Thanks! I added Nix package haskell-language-server to:

environment.systemPackages = with pkgs; [
  ];

in /etc/nixos/configuration.nix and sudo nixos-rebuild switch;

installed, in the normal way:

• Haskell Syntax Highlighting - Visual Studio Marketplace
• Haskell - Visual Studio Marketplace ;

and set:

 "haskell.manageHLS": "PATH"

and all seems good.