anchor.diff:  %% new
   %%------------------------------------------------------------------------------
   ast(#{op := new} = Expr, State) ->
  +  ?DEBUG(new),
     #{ type := TypeExpr
      , args := ArgsExprs
      , env  := Env
  
positive.code: %% Literal data structures
  %%------------------------------------------------------------------------------
  ast(#{op := vector} = Expr, State) ->
    #{ items := ItemsExprs
     , env   := Env
     } = Expr,
  
negative.code: %% throw
  %%------------------------------------------------------------------------------
  ast(#{op := throw} = Expr, State) ->
    ?DEBUG(throw),
    #{ exception := ExceptionExpr
     , env       := Env
     } = Expr,
  