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Repls

• Read-eval-print-loop
• Misc
  • History of REPLs?
  • There's a startup: replit.com
• Papers
  • A principled approach to REPL interpreters
    • https://maveme.github.io/assets/pdfs/Onward2020-preprint.pdf
    • Features considered essential for REPLs
      • Snippet execution
      • Snippet completion
      • Save and load (state, program, snippets)
      • Summary of effects -- previous results
      • Command history
      • Help
      • Modify definitions
    • "Sequential Language"
      • Full input to a REPL is a valid program
      • Written as sequences of valid programs that manipulate context (configuration)
    • REPLs accumulate effects
    • "Exploring interpreters"
      • Allow reverting to a previous good state of the program
    • Interesting references
      • Refers to http://history.siam.org/sup/Fox_1960_LISP.pdf as /probably/ the earliest known REPL.
      • Additionally, Pilot: https://dspace.mit.edu/handle/1721.1/6905
  • Programming with a Read-Eval-Synth-Loop
    • https://dl.acm.org/doi/pdf/10.1145/3428227
    • Looks interesting, and makes me wonder how effective copilot is in REPLs
  • History of REPLs
    • https://www.reddit.com/r/lisp/comments/roov9z/history_when_was_the_repl_invented/
    • http://s3data.computerhistory.org/pdp-1/DEC.pdp_1.1964.102650371.pdf
  • Also referred to as a means for exploratory programming
    • https://link.springer.com/chapter/10.1007/978-3-030-83978-9_2
  • Notebook on top of an exploratory interpreter
    • https://ltvanbinsbergen.nl/files/theses/joey-lai-2021.pdf
    • "viscosity" ease of changing code while preserving design
  • Clojure
    • https://clojure.org/guides/repl/enhancing_your_repl_workflow
      • https://cognitect.com/blog/2013/06/04/clojure-workflow-reloaded
      • Writing code to be REPL friendly

• Notes to self:
  • Explore IPython REPLs; very few people seem to use them the way I do
    • discussion between going between production code and exploratory programming
    • I almost use them like a PHP endpoint -- edit file, refresh page (call function), see changes
      • state is maintained that otherwise wasn't
  • VSCode Jupyter REPLs and their adoption, any discussions online?
  • Figure out the mechanics and shortcomings of %autoreload
    • What would an ideal autoreload look like
      • the idea of being able to revert to a good state is amazing
  • Explore Web App REPLs -- the tech is there, putting it together is missing
  • Explore prominent REPLs and their histories, as well as their forms of interaction; go only for widely adopted variants (ie not pasted on after the fact)
    • Lisps -- get a lisp machine?
      • Clojure
    • Forth
    • Erlang
    • Javascript
    • Smalltalk (why isn't this considered a REPL)
  • Standard shell is also a REPL? yes/no?
    • What about SQL
    • Any CLI that allows interactive programming?
  • Debugger vs repl?
    • is there a difference?

— Kunal