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Raku port of Perl's length() built-in


use P5length; # exports length()

say length("foobar"); # 6
say length(Str);      # Str

$_ = "foobar";
say length;           # 6


This module tries to mimic the behaviour of Perl's length built-in as closely as possible in the Raku Programming Language.


length EXPR
length  Returns the length in characters of the value of EXPR. If EXPR is
        omitted, returns the length of $_. If EXPR is undefined, returns

        This function cannot be used on an entire array or hash to find
        out how many elements these have. For that, use "scalar @array"
        and "scalar keys %hash", respectively.

        Like all Perl character operations, length() normally deals in
        logical characters, not physical bytes. For how many bytes a
        string encoded as UTF-8 would take up, use
        "length(Encode::encode_utf8(EXPR))" (you'll have to "use Encode"
        first). See Encode and perlunicode.


Characters vs codepoints

Since the Perl documentation mentions characters rather than codepoints, length will return the number of characters, as seen using Normalization Form Grapheme (NFG).

Handling of type objects

length in Perl is supposed to return undef when given undef. Since undefined values are type objects in Raku, and it looks like length is simply returning what it was given in the undefined case, it felt appropriate to simply return the given type object rather than Nil.

$_ no longer accessible from caller's scope

In future language versions of Raku, it will become impossible to access the $_ variable of the caller's scope, because it will not have been marked as a dynamic variable. So please consider changing:


to either:


or, using the subroutine as a method syntax, with the prefix . shortcut to use that scope's $_ as the invocant:



Elizabeth Mattijsen liz@raku.rocks

If you like this module, or what I’m doing more generally, committing to a small sponsorship would mean a great deal to me!

Source can be located at: https://github.com/lizmat/P5length . Comments and Pull Requests are welcome.


Copyright 2018, 2019, 2020, 2021, 2023 Elizabeth Mattijsen

Re-imagined from Perl as part of the CPAN Butterfly Plan.

This library is free software; you can redistribute it and/or modify it under the Artistic License 2.0.