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Once upon a time I have implemented POP3 server protocol state machine in Clojure. 180 lines in total, of which 40 were FSM declaration, 140 command handling f

Once upon a time I have implemented POP3 server protocol state machine in Clojure. 180 lines in total, of which 40 were FSM declaration, 140 command handling functions. Not sure I'll ever want to approach FSM in any other language, unless no other choice.

harperlee 7y ago
Can you perhaps point to it? Sounds interesting to read that code!
- juskrey 7y ago
  Yes. Can't share the whole repo (it's our internal product), but here are two files (FSM macro and FSM itself) you can explore. Let me know it that helps. https://gist.github.com/juskrey/61148c98bdde871a8d3743f54b822ae5 https://gist.github.com/juskrey/61148c98bdde871a8d3743f54b82... https://gist.github.com/juskrey/127cf8456fc527d20ed5e244ce01e312 https://gist.github.com/juskrey/127cf8456fc527d20ed5e244ce01...
  - diggan 7y ago
    Interesting, thanks a lot for being able to share those examples! I think you managed to find a bug in the GitHub syntax highlighter, as https://gist.github.com/juskrey/61148c98bdde871a8d3743f54b822ae5 https://gist.github.com/juskrey/61148c98bdde871a8d3743f54b82... has no colors after line ~108.
- diggan 7y ago
  Not OP but there is tons of FSM implementations/libs in Clojure scattered around GitHub and GitLab if you search for them. Some of them: - https://github.com/ztellman/automat https://github.com/ztellman/automat - https://github.com/metosin/tilakone https://github.com/metosin/tilakone - https://github.com/cdorrat/reduce-fsm https://github.com/cdorrat/reduce-fsm
Dowwie 7y ago
Did you iterate to a FSM solution, from many nested conditions, or use it right from the start? I'm fighting the urge to write any FSM without having the absolute certainty that it is needed. There seems no other way than by refactoring to an FSM.
- deleted 7y ago
  [deleted]
- juskrey 7y ago
  I have started from already existing FSM libs (which did not fit well) and after couple of experiments understood that creating own custom FSM processor is a no-brainer with clojure/core.match

harperlee 7y ago

Can you perhaps point to it? Sounds interesting to read that code!

juskrey 7y ago
Yes. Can't share the whole repo (it's our internal product), but here are two files (FSM macro and FSM itself) you can explore. Let me know it that helps. https://gist.github.com/juskrey/61148c98bdde871a8d3743f54b822ae5 https://gist.github.com/juskrey/61148c98bdde871a8d3743f54b82... https://gist.github.com/juskrey/127cf8456fc527d20ed5e244ce01e312 https://gist.github.com/juskrey/127cf8456fc527d20ed5e244ce01...
- diggan 7y ago
  Interesting, thanks a lot for being able to share those examples! I think you managed to find a bug in the GitHub syntax highlighter, as https://gist.github.com/juskrey/61148c98bdde871a8d3743f54b822ae5 https://gist.github.com/juskrey/61148c98bdde871a8d3743f54b82... has no colors after line ~108.
diggan 7y ago
Not OP but there is tons of FSM implementations/libs in Clojure scattered around GitHub and GitLab if you search for them. Some of them: - https://github.com/ztellman/automat https://github.com/ztellman/automat - https://github.com/metosin/tilakone https://github.com/metosin/tilakone - https://github.com/cdorrat/reduce-fsm https://github.com/cdorrat/reduce-fsm

Dowwie 7y ago

Did you iterate to a FSM solution, from many nested conditions, or use it right from the start? I'm fighting the urge to write any FSM without having the absolute certainty that it is needed. There seems no other way than by refactoring to an FSM.

deleted 7y ago
[deleted]
juskrey 7y ago
I have started from already existing FSM libs (which did not fit well) and after couple of experiments understood that creating own custom FSM processor is a no-brainer with clojure/core.match