anchor.diff:  %% Syntax quote
   %%------------------------------------------------------------------------------
   
  +-spec read_syntax_quote(state()) -> state().
   read_syntax_quote(#{src := <<"`"/utf8, _/binary>>, env := Env} = State) ->
     {Form, NewState} = pop_form(read_one(consume_char(State))),
     %% TODO: using process dictionary here might be a code smell
  
positive.code: %% Symbol
  %%------------------------------------------------------------------------------
  
  read_symbol(State) ->
    Loc  = maps:get(loc, State),
    Meta = #{loc => Loc},
  
negative.code: %% #() fn
  %%------------------------------------------------------------------------------
  
  -spec read_fn(state()) -> state().
  read_fn(#{loc := Loc} = State) ->
    case erlang:get(arg_env) of
      undefined -> ok;
  