Simple usage
$ cat config.json
{
"nixInstantiatePath" : "/run/current-system/sw/bin/nix-instantiate",
"nixPath" : [ "nixpkgs=/nix/store/arm3y37s9k9z5axyya210r0z1fryp2cs-nixpkgs/nixpkgs" ],
"exprFilePath": "/tmp/expr.nix",
"token" : "<your telegram bot token>"
}
$ nix-build
$ ./result/bin/nixbot-telegram config.json