Unicode strings

Unicode strings is a draft programming task. It is not yet considered ready to be promoted as a complete task, for reasons that should be found in its talk page.

Task

Demonstrate how one is expected to handle Unicode strings. Some example considerations: can a Unicode string be directly written in the source code? How does one do IO with unicode strings? Can these strings be manipulated easily? Can non-ASCII characters be used for keywords/identifiers/etc? What encodings (UTF-8, UTF-16, etc) can your language accept without much trouble?

Perl

In Perl, "Unicode" means "UTF-8". If you want to include utf8 characters in your source file, unless you have set PERL_UNICODE environment correctly, you should do<lang Perl>use utf8;</lang> or you rick the parser treating the file as raw bytes.

Inside the script, utf8 characters can be used both as identifiers and literal strings, and built-in string functions will respect it:<lang Perl>$四十二 = "voilà"; print "$四十二"; # voilà print uc($四十二); # VOILÀ</lang> or you can specify unicode characters by name or ordinal:<lang Perl>use charnames qw(greek); $x = "\N{sigma} \U\N{sigma}"; $y = "\x{2708}"; print scalar reverse("$x $y"); # ✈ Σ σ</lang>

Regular expressions also have support for unicode based on properties, for example, finding characters that's normally written from right to left:<lang Perl>print "Say עִבְרִית" =~ /(\p{BidiClass:R})/g; # עברית</lang>

When it comes to IO, one should specify whether a file is to be opened in utf8 or raw byte mode:<lang Perl>open IN, "<:utf8", "file_utf"; open OUT, ">:raw", "file_byte";</lang> The default of IO behavior can also be set in PERL_UNICODE.

However, when your program interacts with the environment, you may still run into tricky spots if you have imcompatible locale settings or your OS is not using unicode; that's not what Perl has control over, unfortunately.

PicoLisp

PicoLisp can directly handle _only_ Unicode (UTF-8) strings. So the problem is rather how to handle non-Unicode strings: They must be pre- or post-processed by external tools, typically with pipes during I/O. For example, to read a line from a file in 8859 encoding: <lang PicoLisp>(in '(iconv "-f" "ISO-8859-15" "file.txt") (line))</lang>