sha1 hash

sha1.p6

subset Sha1 of Str where *.chars == 40 and m:i/<[A..F 0..9]>/;

class Sha1H does Associative {
  has %!h;
  method AT-KEY(Sha1 $_) { %!h{ .lc } };
  method ASSIGN-KEY(Sha1 $_, $v) { %!h{ .lc } = $v }
}

my %h is Sha1H;
my  $sha1 = '64B0F6C3681E428CCE2EB830B05F27B3D7ED643E';
say $sha1.chars;
%h{$sha1} = 'a';
say %h{$sha1};
%h<a> = 'b'; # fail here because not Sha1 :)