nREPL Redux (DCD 2019)

Slide-deck from my presentation at Dutch Clojure Days 2019.

Transcript

1. M-x
2. M-x greet-audience
3. Божидар
4. Bug cool
6. Sofia, Bulgaria Sofia, Bulgaria
10. We’re not hiring!
12. @bbatsov
13. metaredux.com
14. emacsredux.com
16. slide intentionally left blank
17. nREPL REdux
18. Dictionary Definitions
19. nREPL
20. network REPL
21. redux
22. adjective 1. brought back, revived Emacs era redux 2. (usually postpositive) (esp of an artistic work) presented in a new way Apocalypse Now Redux
23. nREPL Redux?
24. nREPL is legacy
25. nREPL is complex
26. (nREPL) middleware sucks
27. Rich hates nREPL
28. The Socket REPL is the future
29. unrepl is the future
30. prepl is the future
31. LSP is the future
32. notorious REPL
33. nice REPL
34. neo REPL
35. noble REPL
36. novel REPL
37. mREPL
38. mega REPL
39. mighty REPL
40. magic REPL
41. magnificent REPL
42. marvellous REPL
43. majestic REPL
44. Naming is hard!
45. nREPL REdux
46. nREPL is very actively maintained
47. nREPL is not complex
48. Simple by design
49. nREPL is superbly documented
51. Middleware is a very powerful concept
52. A huge ecosystem of tools exists around nREPL
53. lein repl
54. boot repl
55. vim-fireplace
56. vim-iced
57. acid.vim
58. Calva (VS Code)
59. Proto REPL (Atom)
60. Cursive
62. A REPL for (Great) Good
64. vim-clojure custom SLIME swank Enclojure custom CCW custom
65. vim-clojure nREPL SLIME nREPL Enclojure nREPL CCW nREPL
66. Project Goals •Common foundation for Clojure tooling •Trivial to embed •Zero runtime dependencies •Extremely simple wire format •Easy to extend with additional functionality
67. vim-fireplace nREPL CIDER nREPL Cursive nREPL CCW nREPL vim-iced nREPL Calva nREPL acid.vim nREPL Proto REPL nREPL
69. Clojure Contrib
70. org.clojure/tools.nrepl
71. •Contributor Agreement •No Pull Requests •JIRA for issue tracking •Hudson CI •Maven •Artifacts are deployed to Maven Central
74. The (REPL) Wasteland
75. github.com/clojure/tools.nrepl Repo deprecation announcement
77. 17 contributors in 8 years
78. Almost no activity since 2015
79. 25% 5% 70% Yes Maybe I already have Notepad No Do you want great Clojure development tools?
80. 69% 25% 5% 1% Yes Maybe I already have Notepad No Are you willing to work on Clojure development tools?
81. SLIME -> CIDER
82. CIDER loves nREPL
85. Rogue One
86. Challenges
87. I didn’t really know what I had signed up for
88. Breaking changes to one of the most widely used tools in the Clojure ecosystem
89. org.clojure/tools.nrepl -> nrepl/nrepl
90. clojure.tools.nrepl.* -> nrepl.*
91. A ton of 3rd party tools and libraries needed to be updated
92. •lein •boot •figwheel •shadow-cljs •REPLy •Ultra •All nREPL extensions in existence…
93. •piggieback •cider-nrepl •refactor-nrepl •sayid •drawbridge •and many others…
94. Migration Strategy • Teach most extensions about both versions of nREPL • Migrate tools like Lein and Boot to the new nREPL • Provide ways for users of older Boot/Lein to run the new nREPL • Drop support for tools.nrepl from the extensions • Document nREPL extensively in the process • Focus on actual nREPL improvements
95. Building a community around the project
96. A Catalyst for Change
97. REPL (R)Evolution
98. •nREPL 0.3 (initial compatibility release) •nREPL 0.4 (multiple feature releases) •nREPL 0.5 •nREPL 0.6
99. Better Versioning Policy
100. 0.feature.patch
101. Then •0.2.5 (Feature) •0.2.6 (Feature) •0.2.7 (Bug fix) •0.2.8 (Feature)
102. Now •0.5.0 (Feature) •0.5.1 (Bug fix) •0.5.2 (Bug fix) •0.6.0 (Feature)
103. Clear Compatibility Policy • All supported LTS JDKs (Currently Java 8 and Java 11) • Latest rapid cycle JDK (Currently Java 12) • Clojure 1.7+ • Extreme dedication to protocol compatibility • Surgical changes at the implementation-level
104. Fixed many long-standing bugs
105. Complete overhaul of the internals
106. •Simpler code evaluation model •Robust handling of Clojure’s special variables •Massively improved value printing logic •Better way to hook into evaluation errors •Global/project server configuration via configuration files •Reusable command-line API
107. Exhaustive documentation (nrepl.org)
108. Great integration with tools.deps
109. Transit transport (https://github.com/nrepl/fastlane)
110. EDN transport (coming in nREPL 0.7)
111. Support for hot-loading libraries in a running REPL
112. No breaking changes to the protocol
113. Minimal breaking changes on the API level
114. Team-work FTW
115. Chas creates the new repo Rogue One
117. 23 new contributors!
118. Christophe Grand
119. Michael Griffiths
122. Monopoly is good
123. Monopoly allows you to focus on innovation
124. Meet The Competition
125. The Socket REPL
126. •bundled with Clojure & ClojureScript •streaming REPL •a socket based version of the default REPL •easy if you want to evaluate something in a remote app •can be started with a JVM property •hard to build tools on it
127. $ clj -J-Dclojure.server.jvm="{:port 5555 :accept clojure.core.server/repl}” $ nc localhost 5555 user=> (+ 10 10) 20 user=> (println "Hello, world!") Hello, world! nil
128. prepl
129. $ clj -J-Dclojure.server.jvm="{:port 5555 :accept clojure.core.server/io-prepl}” $ nc localhost 5555 (+ 10 10) {:tag :ret, :val "20", :ns "user", :ms 23, :form "(+ 10 10)”} (println "Hello, world") {:tag :out, :val "Hello, world\n"} {:tag :ret, :val "nil", :ns "user", :ms 8, :form "(println \"Hello, world\")"}
130. unrepl
131. •based on the socket REPL •allows clients to customize the REPL •has a sophisticated rich data printer •streaming input, framed EDN output
132. Language Server Protocol • Language agnostic • Doesn’t rely on a running REPL • A much broader protocol (completions, code lookup, etc) • Usually is implemented in terms of static analysis • Message oriented, JSON data format • Extensible protocol • Controlled by an evil corporation turned good
134. Swiss army knife of REPLs
135. • designed to power programmings tools • message oriented • can be extended with arbitrary operations • interruptible evals • session multiplexing • supports arbitrary communication protocol/data format • async in nature
136. ;; request {:id "1" :op "eval" :code "(+ 1 1)” :ns "user"} ;; response {:id "1" :value "2"}
137. ;; request {:id "1" :op "complete" :thing "map” :ns "user"} ;; response {:id "1" :candidates […]}
138. ;; raw request {:id 1 :op "eval" :code "(+ 1 1)"} ;; encoded request “d4:code7:(+ 1 1)2:idi1e2:op4:evale"
139. “d4:code7:(+ 1 1)2:idi1e2:op4:evale" •d (dictionary) •4:code - a 4 byte string “code” •7:(+ 1 1) - a 7 byte string “(+ 1 1)” •2:id - a 2 byte string “id” •i1e - an integer 1 •… •e - end of dictionary
140. Community Driven
141. Open Source is not about You
142. nREPL is all about YOU!!!
143. Beyond Clojure
144. nREPL as a protocol
145. Simple by design
146. Key Operations •eval •load-file •interrupt •stdin
147. Bencode Data Types •strings •integers •lists •maps
149. A light-weight alternative to LSP
150. Easy to implement
151. nREPL implementations •HyREPL - an nREPL for the Hy programming language •JeeJah - an nREPL server for Fennel and Lua •Ogion - an nREPL server for Racket •Chicken NREPL - an nREPL server for Chicken Scheme •cl-nrepl - an nREPL server for Common Lisp •cljs-noderepl - an nREPL server for ClojureScript running on Node.js •R-nREPL - an nREPL server for R •nREPL CLR - an nREPL server for ClojureCLR •Arcadia nREPL - an nREPL server implemented in C# for Arcadia.
152. Dreams for the future • nREPL implemented in ClojureScript/ClojureCLR • nREPL for Erlang/Elixir • nREPL for Smalltalk • Better behaved nREPL clients (ones that don’t make assumptions they are dealing with a Clojure server)
153. (next nrepl)
154. Roadmap for nREPL 0.7 •EDN Transport (done) •Client-side resource/class injection API (unrepl) •Upgrade socket REPL to nREPL (unrepl) •Rich data printer (unrepl)
155. Personal Impact
156. Extremely proud
158. Frustrated
159. Tired
160. Burned out
164. Sustainable
165. Community Funded?
166. Clojure’s Orchard
167. $4000
168. $5400
169. We need to get Clojure companies invested in the Clojure tooling ecosystem
170. 20 companies paying $500/month can make a massive difference
171. Funding channels •https://opencollective.com/nrepl •https://opencollective.com/cider •https://patreon.com/bbatsov •https://paypal.me/bbatsov
172. Help nREPL…
173. …to help yourselves
174. –Old Dutch Saying “You can’t build an epic Clojure programming experience on top of a poor REPL.”
175. Felina
176. Resources • https://metaredux.com/posts/2018/10/29/nrepl-redux.html • https://metaredux.com/posts/2019/01/12/nrepl-beyond- clojure.html • https://metaredux.com/posts/2019/03/29/nrepl-0-6.html • https://www.youtube.com/watch?v=4X-1fJm25Ww
177. Credits twitter: @bbatsov github: @bbatsov https://metaredux.com https://emacsredux.com DCD 2019 Amsterdam, The Netherlands 06.04.2019