RPR

$ echo 'puts "Hello world"' > hello.rb
$ rpr hello.rb
[:program,
 [[:command,
   [:@ident, "puts", [1, 0]],
   [:args_add_block,
    [[:string_literal,
      [:string_content, [:@tstring_content, "Hello world", [1, 6]]]]],
    false]]]]

$ rpr hello.rb --parser rubocop
s(:send, nil, :puts,
  s(:str, "Hello world"))

$ rpr hello.rb --method tokenize
["puts", " ", "\"", "Hello world", "\"", "\n"]

$ rpr hello.rb --formatter json
[
  "program",
  [
    [
      "command",
      [
        "@ident",
        "puts",
        [
          1,
          0
        ]
      ],
      [
        "args_add_block",
        [
          [
            "string_literal",
            [
              "string_content",
              [
                "@tstring_content",
                "Hello world",
                [
                  1,
                  6
                ]
              ]
            ]
          ]
        ],
        false
      ]
    ]
  ]
]

$ rpr hello.rb --formatter pry
[1] pry(#<Array>)> self
=> [:program, [[:command, [:@ident, "puts", [1, 0]], [:args_add_block, [[:string_literal, [:string_content, [:@tstring_content, "Hello world", [1, 6]]]]], false]]]]
[2] pry(#<Array>)> ls
Enumerable#methods:
  all?   chunk_while     detect     each_entry  each_with_index   entries  find_all  grep    group_by  lazy  max_by   min     minmax     none?  partition  slice_after   slice_when
  chunk  collect_concat  each_cons  each_slice  each_with_object  find     flat_map  grep_v  inject    max   member?  min_by  minmax_by  one?   reduce     slice_before  sort_by
Array#methods:
  &  <<   []=    bsearch        collect!     concat  delete_at  drop_while  eql?        first     hash      inspect  length  permutation         product  reject!               reverse       rotate   select!    shuffle!  sort      take_while  to_s       unshift
  *  <=>  any?   bsearch_index  combination  count   delete_if  each        fetch       flatten   include?  join     map     pop                 push     repeated_combination  reverse!      rotate!  shelljoin  size      sort!     to_a        transpose  values_at
  +  ==   assoc  clear          compact      cycle   dig        each_index  fill        flatten!  index     keep_if  map!    pretty_print        rassoc   repeated_permutation  reverse_each  sample   shift      slice     sort_by!  to_ary      uniq       zip
  -  []   at     collect        compact!     delete  drop       empty?      find_index  frozen?   insert    last     pack    pretty_print_cycle  reject   replace               rindex        select   shuffle    slice!    take      to_h        uniq!      |
self.methods: __pry__
locals: _  __  _dir_  _ex_  _file_  _in_  _out_  _pry_
[3] pry(#<Array>)> exit

$ rpr hello.rb -f dot | dot -Tpng -oast.png
$ open ast.png