Intersperse function in Perl 6 and Haskell

intersperse.hs

intersperse             :: a -> [a] -> [a]
intersperse _   []      = []
intersperse sep (x:xs)  = x : prependToAll sep xs

prependToAll            :: a -> [a] -> [a]
prependToAll _   []     = []
prependToAll sep (x:xs) = sep : x : prependToAll sep xs

intersperse.p6

multi intersperse ($, []) { [] }
multi intersperse ($sep, [$x, **@xs]) {
    $x, |prepend_to_all($sep, @xs)
}

multi prepend_to_all ($, []) { [] }
multi prepend_to_all ($sep, [$x, **@xs]) {
    $sep, $x, |prepend_to_all($sep, @xs);
}

say intersperse 0, [1,2,3];
say intersperse <X Y>, [<a b>, <c d>, <e f>];
# say intersperse(0, 1..*);
# say intersperse(0, 1...*);