 end
 
 defmodule TokenMissingError do
-  defexception [file: nil, line: nil, description: "expression is incomplete"]
+  defexception [:file, :line, description: "expression is incomplete"]
 
   def message(%{file: file, line: line, description: description}) do
     Exception.format_file_line(file && Path.relative_to_cwd(file), line) <>

end

defmodule BadMapError do
  defexception [term: nil]

  def message(exception) do
    "expected a map, got: #{inspect(exception.term)}"

end

defmodule FunctionClauseError do
  defexception [:module, :function, :arity]

  def message(exception) do
    if exception.function do
