Anyway, the very bleak humour in this is that all the characters are school kids (though played by actors in their twenties). It's not like 'Bugsy Malone' - there's real violence. But it is very funny to hear noir dialogue, as you might recognise from scenes in other films between a police chief and a private eye, in the mouth of a Vice Principal telling a kid off for not going to class. Or the scene in Red Harvest where the 'private eye' is beaten unconscious by the henchman, followed in this version by the protagonists eating cereal in a kitchen under the watchful eye of the chief gangster's mum.
And yet, of course kids of this age do get killed, get pregnant, get addicted and exploited. And they aren't listened to. Just in the month I have been teaching there has been serious stuff happened to kids in my classes, which would challenge any adult. The use of highly stylised noir dialogue is, as I say, comic, but also provides a way for adults to see into the world of children, in adult terms. I would like to see more recognition that the suffering of children is as serious as the suffering of adults.
Turning it around, the restrictions and powerlessness of children enables the noir plot to unfold, and makes clear the alienation and futility which Hammett's communist novel was portraying.
(I'm actually posting this before I have seen the whole film, because I have to go to work now)