Natural collation

natural-collation.p6

sub natural ($a) { $a.subst(/(\d+)/, ->$/ {0~$0.chars~$0},:g)~$a }

sub ncollate (@list){     # this works... but yuck
    @list[@list.kv.map( { [$^k, $^v.&natural] } ).sort( { $^a[1] unicmp $^b[1] } )[*;0]]
};

my @words = <32nd 3rd 144th 17th 2 95 apple ball Bald
             Æon æon aether Évian evoke außen Autumn file3 file21 file17>;

#say @words.sort;
#say @words.collate;
#say @words.sort( &[coll] );
#say @words.sort( *.&natural );
#say @words.sort( *.fc.&natural );
say @words.&ncollate;

# if the collate transfor routine is exposed, we can then use it a single
# arity tranform routine to sort... which can then easily be chained.
# Instead of the ugly ncollate routine I am envisioning something like:

#say @words.sort( *.&natural.&collated );