Right, thanks. Don't get me wrong, I like Haskell (though haven't got good at it yet; keep getting lost somewhere between fmap and applicatives/monads). Howeve

Right, thanks. Don't get me wrong, I like Haskell (though haven't got good at it yet; keep getting lost somewhere between fmap and applicatives/monads). However, I prefer the comprehension and `do` version over your `fmap` expression. The reason is that I think that filtering and transforming a stream is sufficiently common/important that a language should provide declarative syntax / a DSL for it. Whereas your `fmap` version makes too many implementation details explicit: all that should be needed is for the programmer to say "lazily filter and transform these values". I think it would be ideal for the programmer not to have to worry about `fmap` and `$`, and I think the expression should read more naturally than your fmap example. The Python and Haskell comprehension versions pass the "read naturally" test very well: "create a set/stream of manipulated items where the items pass the filter". The Haskell `fmap` version reads as "apply the manipulate function to a functor where, oh by the way the functor is a kind of list, and oh by the way use $ to separate arguments in this expression, but as I was saying do that but filter the list first". EDIT: I don't mean to imply that I know how Haskell should be written, I defer to you; the sophistication of Haskell's functor-related abstractions is such that I bet you're right that the special case syntax of a comprehension is kind of an annoying presence in the language (but that still leaves two ways to do it?). But, we were talking about javascript and there I think it makes a lot of sense to give the world a way to construct collections declaratively.