ast.md
In lobstr: Visualize R Data Structures with Trees

can print complex expression

Code
  ast(!!x)
Output
  █─`function` 
  ├─█─x = `` 
  ├─█─`if` 
  │ ├─█─`>` 
  │ │ ├─x 
  │ │ └─1 
  │ └─█─f 
  │   ├─█─`$` 
  │   │ ├─y 
  │   │ └─x 
  │   ├─"x" 
  │   └─█─g 
  └─<inline srcref>

can print complex expression without unicode

Code
  ast(!!x)
Output
  o-`function` 
  +-o-x = `` 
  +-o-`if` 
  | +-o-`>` 
  | | +-x 
  | | \-1 
  | \-o-f 
  |   +-o-`$` 
  |   | +-y 
  |   | \-x 
  |   +-"x" 
  |   \-o-g 
  \-<inline srcref>

can print scalar expressions nicely

Code
  ast(!!x)
Output
  o-list 
  +-logical = o-c 
  |           +-FALSE 
  |           +-TRUE 
  |           \-NA 
  +-integer = 1L 
  +-double = 1 
  +-character = "a" 
  \-complex = 1i