-- main.mcl --
$prefix = "hello"

# this should be a function as a value, iow a lambda
$prefixer = func($x) {
	$prefix + ":" + $x	# i'd only ever expect one ":" in the graph
}

$out1 = $prefixer("world")
$out2 = $prefixer($out1)

test $out1 {}
test $out2 {}
-- OUTPUT --
Vertex: test[hello:world]
Vertex: test[hello:hello:world]