Fuzion • Idioms • Idiom # 186: Exit program cleanly

Idiom # 186: Exit program cleanly

Code

exit 0

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exit 0
 
 
הההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההה
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What are effects?

Running Example

Note that exit is an effect that can have different implementations. The default behaviour is to exit the program:

ex186 is

  f =>
    say "perform exit:"
    exit 0
    say "** not reachable code **"

  f
  say "** not reachable code **"

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ex186 is
  f =>
    say "perform exit:"
    exit 0
    say "** not reachable code **"
  f
  say "** not reachable code **"
 
 
הההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההה
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What are effects?

However, we might provide a different handler for this effect that continues the execution of the program:

ex186a is

  f =>
    say "perform exit:"
    exit 0
    say "** not reachable code **"

  my_exit : Exit_Handler is
    public redef exit(code u8) void =>
      io.err.println "*** user defined exit handler diverting exit $code ***"
      exit.abort

  exit my_exit ()->
    f
    say "** not reachable code **"

  say "continue even though exit was called..."

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ex186a is
  f =>
    say "perform exit:"
    exit 0
    say "** not reachable code **"
  my_exit : Exit_Handler is
    public redef exit(code u8) void =>
      io.err.println "*** user defined exit handler diverting exit $code ***"
      exit.abort
  exit my_exit ()->
    f
    say "** not reachable code **"
  say "continue even though exit was called..."
 
 
הההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההה
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What are effects?

last changed: 2025-05-13

next: Idiom # 187: Disjoint Set