Course of Raku / Essentials

Notes on using Unicode

Raku assumes that all your program files are saved as UTF-8 files. From the practical point of view, that means that you don’t have to worry about non-ASCII characters in, for example, string literals. But that’s not only that. You most likely will not need to worry if your program reads a text file that is also a UTF-8 file. It also means that string length is correctly detected as the number of characters and not the number of bytes. (We will have a more detailed look into it later.)

The next thing you want to know is that you can use non-Latin or non-English letters for identifiers. You can name your variable $ι instead of $i if you prefer, and the compiler will parse it correctly.

Raku treats the Unicode properties of the characters pedantically enough. For example, it not only knows if a character is a letter or a digit, but also correctly identifies pair characters such as parentheses or different kind of brackets. In many cases, you can choose a different type of brackets for separate parts of the program. For instance, you can modify our ‘Hello, World!’ program to use these non-Latin quoting characters (you will see them again when we’ll work with Raku grammars):

say ｢Hello, World!｣;

Some built-in operators have two forms: a Unicode and an ASCII versions. For example, one can type a negated comparison as != or as ≠. The same applies to set operations: for instance, ∈ has a pure ASCII equivalent (elem). Or, there is a built-in constant which you can refer to as pi or π.

When working with numbers, you can choose to use fractions in the form of ½ instead of 0.5. Or, evaluating the square of $x as $x² using a superscript character.

Find the full list of such pairs at the following documentation page: 📖 Unicode versus ASCII symbols.

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