Character translation — trans with ranges

Map whole ranges of characters at once — upcasing, rot13, and the like.

.trans translates characters by a mapping. Beyond single characters (see String methods), the two sides can be ranges, so a whole alphabet maps in one go — the tr/// of other languages, generalised.

Range-to-range mapping #

say "hello".trans("a..z" => "A..Z");
say "abc".trans("abc" => "xyz");

HELLO
xyz

"a..z" => "A..Z" maps each lowercase letter to its uppercase counterpart by position.

rot13 in one call #

Multiple ranges concatenate, so a single .trans can rotate both cases — the classic rot13.

say "Hello".trans("a..zA..Z" => "n..za..mN..ZA..M");

Uryyb

Notes #

• The from- and to-sides are matched position by position, so their lengths must correspond; a range on one side pairs with a range of equal size on the other.
• Pass a list of pairs to apply several independent mappings at once: .trans(['a' => '1', 'b' => '2']).
• Unlike a regex substitution, .trans is a pure per-character map — fast and with no backtracking — ideal for transliteration.