CODEWITHSUNDEEP
blockexitraku
Timothy Nelson
Timothy Nelson

Reputation: 575

Raku last on non-loops

I have something that I can do easily in Perl, but not in Raku without fiddling around with flag variables. Here's the Perl code:

#!/usr/bin/perl

MAIN_BLOCK: {
        foreach $item (1 2 3 4 5) {
                $item == 6 and last MAIN_BLOCK;
        }
        print "No items matched!\n";
}

The relevant difference here is that Perl will allow you to use last to exit from any labelled block. Raku will only do this if the block is a loop.

Is there a good way to do this? I feel like there should be a phaser for this, but haven't figured out how to do it without flag variables, which seem like they should be avoidable.

Thanks,

Upvotes: 7

Views: 200

Answers (1)

codesections
codesections

Reputation: 9600

Raku supports similar control flow with given blocks.

Here's a fairly literal translation (i.e., not necessarily idiomatic Raku) from the Perl code you posted:

given * {
    for ^6 -> $item {
        succeed if $item == 6;
    }
    default { print "No items matched!\n"; }
}

edit: Oh, and for a less-literally-translated/more-idiomatic-Raku solution, well, TIMTOWTDI but I might go with returning from an anonymous sub:

sub { for ^6 { return when 6 }
      say "No items matched!" }()

(Of course, I suppose it's possible that the most Raku-ish way to solve do that doesn't involve any Raku syntax at all – but instead involves modifying one of Raku's braided languages to allow for loops to take an else block. But I'm not advising those sort of shenanigans!)

Upvotes: 6

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