The various synopses contain many mentions of Iterators. These are used, for instance, to implement lazy lists so the expression 1..1_000_000 does not have to allocate a million element array. But as far as I can tell the term is never defined anywhere in the synopses. Is Iterator a role, and if so what methods is it required to have? Do functions like map and grep, which in Perl5 return lists, return Iterators in Perl6? Can an Iterator be passed to a function (like map and grep again) that requires a list as an input? Does an array or hash have only one Iterator or can it have several independent ones?
Joe Gottman
