It seems like that problem is needlessly being complicated by conflating key extraction and sorting. (This was an issue that was discussed on perl6-language about the current sort operator — how do we make it possible to isolate the extraction code from the actual sort order, which should then be possible to request declaratively?)
sub order_of_sorted {
my ( @num, @suff );
for( @_ ) {
m/ \A (\d+) \. (.*) /x or die "malformed data";
push @num, $1;
push @suff, $2;
}
sort { $num[$a] <=> $num[$b] or $suff[$a] cmp $suff[$b] } 0 .. $#_
+;
}
for my $outer ( ( values %hash )[ order_of_sorted keys %hash ] ) {
for my $inner ( ( values %$outer )[ order_of_sorted keys %$outer ]
+ ) {
# ...
}
}
If you want to store the data rather than output it, you can transform the nested for-loops to an equivalent chain of maps (but note that that doesn't make it an ST).
I know which version I'd prefer to maintain, even though this is probably slower than your GRT.
Update: the following, which I originally wrote, is obviously wrong:
for my $inner ( ( values %$outer )[ order_of_sorted keys %$inner ]
+) {
# ^^^^^^^ Correct. ^^^^^^^ Oo
+ps.
Makeshifts last the longest.
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