ajs

#Toward a Specification for Perl 6-like Regular Expressions

##Notation

"..." will be used throughout this document to indicate some arbitrary content, which should be explained subsequently.

Otherwise, very little is left to the reader to imagine other than when we get to language-specific concepts.

##Unicode

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use v6;

class Filename is Str {
    # Do some filename type stuff, here...
}

sub MAIN(
    :$foo is copy where { $foo = Filename.new: :value($foo) }
    #= A filename argument.
  ) {

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use v6;

class Filename is Str {
    # Do some filename type stuff, here...
}

sub MAIN(
    Filename(Str) :$foo
    #= A filename argument.
  ) {

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# A trivial program that breaks when run like so:
#  perl6 --target=PIR --output=broken.pir broken.p6
#  parrot broken.pir

use v6;

BEGIN { say "begin" }
START { say "start" }
ENTER { say "enter" }

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role EXPRish is Parser {}
grammar EXPR does EXPRish {
  rule TOP { <expr> }
  rule expr { <num> '+' <num> | <num> }
  token num { (\d+) }
}
class EXPR::Actions does EXPRish {
  action TOP { make $<expr>.ast }
  action expr {
    if $<num>.elems == 1 {

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# Based on Python's itertools.tee, takes a list and a count and returns
# count number of iterators, each of which will "contain" all elements
# of the input list, but without evaluating/flattening the input list
# until needed.
#
sub tee(@list, :$count = 2) {
        my @indices = 0...^$count;
        my @inputs = @indices.map({[]});
        my $maketee = -> $i {
                gather loop {