対処法

以下のコマンドで解決しました。

ln -s /usr/local/opt/readline/lib/libreadline.8.0.dylib /usr/local/opt/readline/lib/libreadline.7.dylib

経緯

何かをインストールしてからpryを起動しようとして、以下のようなエラーが出てしまいました。

Sorry, you can't use Pry without Readline or a compatible library.
Possible solutions:
 * Rebuild Ruby with Readline support using `--with-readline`
 * Use the rb-readline gem, which is a pure-Ruby port of Readline
 * Use the pry-coolline gem, a pure-ruby alternative to Readline
/Users/v97ug/.rvm/rubies/ruby-2.3.0/lib/ruby/site_ruby/2.3.0/rubygems/core_ext/kernel_require.rb:55:in `require': dlopen(/Users/v97ug/.rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/x86_64-darwin16/readline.bundle, 9): Library not loaded: /usr/local/opt/readline/lib/libreadline.7.dylib (LoadError)
  Referenced from: /Users/v97ug/.rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/x86_64-darwin16/readline.bundle
  Reason: image not found - /Users/v97ug/.rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/x86_64-darwin16/readline.bundle
    from /Users/v97ug/.rvm/rubies/ruby-2.3.0/lib/ruby/site_ruby/2.3.0/rubygems/core_ext/kernel_require.rb:55:in `require'
    from /Users/v97ug/.rvm/rubies/ruby-2.3.0/lib/ruby/gems/2.3.0/gems/pry-0.11.3/lib/pry/config/default.rb:139:in `lazy_readline'
    from /Users/v97ug/.rvm/rubies/ruby-2.3.0/lib/ruby/gems/2.3.0/gems/pry-0.11.3/lib/pry/config/default.rb:7:in `block in <class:Default>'
    from /Users/v97ug/.rvm/rubies/ruby-2.3.0/lib/ruby/gems/2.3.0/gems/pry-0.11.3/lib/pry/config/memoization.rb:25:in `instance_eval'
    from /Users/v97ug/.rvm/rubies/ruby-2.3.0/lib/ruby/gems/2.3.0/gems/pry-0.11.3/lib/pry/config/memoization.rb:25:in `block (2 levels) in def_memoized'
    from /Users/v97ug/.rvm/rubies/ruby-2.3.0/lib/ruby/gems/2.3.0/gems/pry-0.11.3/lib/pry/config/behavior.rb:183:in `public_send'
    from /Users/v97ug/.rvm/rubies/ruby-2.3.0/lib/ruby/gems/2.3.0/gems/pry-0.11.3/lib/pry/config/behavior.rb:183:in `method_missing'
    from /Users/v97ug/.rvm/gems/ruby-2.3.0@global/gems/pry-0.11.3/lib/pry/history.rb:19:in `restore_default_behavior'
    from /Users/v97ug/.rvm/gems/ruby-2.3.0@global/gems/pry-0.11.3/lib/pry/history.rb:14:in `initialize'
    from /Users/v97ug/.rvm/gems/ruby-2.3.0@global/gems/pry-0.11.3/lib/pry/pry_class.rb:33:in `new'
    from /Users/v97ug/.rvm/gems/ruby-2.3.0@global/gems/pry-0.11.3/lib/pry/pry_class.rb:33:in `history'
    from /Users/v97ug/.rvm/gems/ruby-2.3.0@global/gems/pry-0.11.3/lib/pry/pry_class.rb:245:in `load_history'
    from /Users/v97ug/.rvm/gems/ruby-2.3.0@global/gems/pry-0.11.3/lib/pry/pry_class.rb:149:in `final_session_setup'
    from /Users/v97ug/.rvm/gems/ruby-2.3.0@global/gems/pry-0.11.3/lib/pry/cli.rb:84:in `parse_options'
    from /Users/v97ug/.rvm/gems/ruby-2.3.0@global/gems/pry-0.11.3/bin/pry:11:in `<top (required)>'
    from /Users/v97ug/.rvm/gems/ruby-2.3.0/bin/pry:23:in `load'
    from /Users/v97ug/.rvm/gems/ruby-2.3.0/bin/pry:23:in `<main>'
    from /Users/v97ug/.rvm/gems/ruby-2.3.0/bin/ruby_executable_hooks:15:in `eval'
    from /Users/v97ug/.rvm/gems/ruby-2.3.0/bin/ruby_executable_hooks:15:in `<main>'

それでググったら以下の記事を見つけたのでその通りにやったらできました。（パスは少し変えています）

Rails consoleでエラーが出た場合

$ ln -s /usr/local/opt/readline/lib/libreadline.8.0.dylib /usr/local/opt/readline/lib/libreadline.7.dylib
$ pry
[1] pry(main)>