amb.p6

# possible solution for http://rosettacode.org/wiki/Amb

my @a =
(all «the that a»),
(all «frog elephant thing»),
(all «walked treaded grows»),
(all «slowly quickly»);

sub test (Str $l, Str $r) {
    $l.ends-with($r.substr(0,1))
}

(sub ($w1, $w2, $w3, $w4){
        return unless [and] test($w1, $w2), test($w2, $w3),test($w3, $w4);
        say "$w1 $w2 $w3 $w4"
})(|@a);

# prints "that thing grows slowly"