ℙ𝕖𝕡 🙴 ℕ𝕠𝕞

Que nos quiten lo bailao Spanish Untranslatable Saying of great profundity.

the ℕ𝕠𝕞 "quit" command

This command immediately exits out of the nom script without processing any more script commands or input stream characters. The command takes no parameters. The current value of the accumulator register is returned as an exit code for the script. So, to follow, normal conventions, the accumulator should be set to zero (if it was altered) before executing quit .

a successful script exit

 clear; add "all good!"; print; zero; quit;

exit with some error condition 2

 clear; add "not good!"; print; zero; a+; a+; quit;

This command is often used when some kind of format or syntax error is detected in the input or it is used at the end of the input-stream.

exit the script if a 'bad' character is found



    read; 
    [:alnum:],[:space:] { print; clear; }
    !"" {
      put; clear;
      add "! strange character found '"; get; add "'\n";
      add "  sampai jumpa lagi...\n"; print;
      # exit with exit code 1.
      zero; a+; quit;
    }

The idiom above of handling different character classes and then clearing the workspace buffer. Then we can use the workspace not empty" text ( !""* ) to check for characters that should not be in the input-stream for whatever format that ℕ𝕠𝕞 is parsing or transforming.

using quit when a syntax error is encountered



    # script snippet ...
    "parameter*parameter*" {
      clear; 
      add "! Error in input at line "; lines; add " \n";
      add "! character "; chars; add "\n";
      add " (Multiple parameters are not allowed in 'Gurgle')";
      print; 
      zero; a+; quit;
    }

notes

The nom commands while , whilenot and until do not automatically exit when the EOF marker is encountered in the input-stream. So, in this case an explicit quit command must be used, if desired.

a required quit at end-of-file or stream



    while [:space:]; clear;
    whilenot [:space:]; add "\n"; print; clear; 
    # without this quit the script will never exit.
    (eof} { quit; }

The read command will automatically (and 'silently') exit the script when the end-of-stream is encountered. This is what it is supposed to do, but sometimes it is surprising and mysterious.

Some compilers or interpreters (such as gcc or perl or rust) will produce a vast number of errors if you make one teensy little error in the program or script. For example in perl, if you forget a semi colon as the end of a statement, you get an incredible litany of rubbish error messages, non of which mention the actual problem. I think this is silly and that compilers should really on display the first encountered error, because all the others may be spurious. So, in my nom scripts I just print a hopefully helpful error message (often using an error* parse token) and then quit the script with an appropriate error code in the accumulator

This command is similar to the SED command 'q'