Tagged location in the source code
Labels are used in Raku to tag loops so that you can specify the specific one you want to jump to with statements such as
last. You can use it to jump out of loops and get to outer ones, instead of just exiting the current loop or going to the previous statement.
USERS: # the labelfor ->say USERS.^name; # OUTPUT: «Label␤»
Those labels are objects of type
Label, as shown in the last statement. Labels can be used in any loop construct, as long as they appear right before the loop statement.
my = 0;my = 0;my = '';A: while ++ < 2say ; # OUTPUT: «A1B1A1A2␤»
Putting them on the line before the loop or the same line is optional.
Labels must follow the syntax of ordinary identifiers, although traditionally we will use the latin alphabet in uppercase so that they stand out in the source. You can use, however, other alphabets like here:
駱駝道: while True# OUTPUT: «駱駝道␤»
Not terribly useful, returns the name of the defined label:
A: while True
Returns the file the label is defined in.
Returns the line where the label has been defined.
Converts to a string including the name, file and line it's been defined in.
Begin the next iteration of the loop associated with the label.
MY-LABEL:for 1..10# OUTPUT: «5 6 7 8 9 10 »
Repeat the same iteration of the loop associated with the label.
my = False;MY-LABEL:for 1..10# OUTPUT: «1 2 3 4 5 5 6 7 8 9 10 »
Terminate the execution of the loop associated with the label.
MY-LABEL:for 1..10# OUTPUT: «1 2 3 4 5 »