Fuzion • Idioms • Idiom # 198: Abort program execution with error condition

Idiom # 198: Abort program execution with error condition

Code

exit x

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exit x
 
 
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:

ex198 is

  f =>
    say "in f, perform exit:"
    x := u8 4
    exit x
    say "** not reachable code **"

  f
  say "** not reachable code **"

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ex198 is
  f =>
    say "in f, perform exit:"
    x := u8 4
    exit x
    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:

ex198a is

  f =>
    say "in f, perform exit:"
    x := u8 4
    exit x
    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 "exit normally"

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ex198a is
  f =>
    say "in f, perform exit:"
    x := u8 4
    exit x
    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 "exit normally"
 
 
הההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההה
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What are effects?

last changed: 2025-05-13

next: NYI: Idiom # 199: Truncate a file at the current file position