[coolsunglasses]

Haste is a strong, useful, and impressively complete Haskell to JS compiler.

Fay is used in production apps as well.

PureScript is less mature still but pretty nice.

[spyder81]

I looked at Haskell options - fay and haste are both good, but not complete (try compiling tagsoup). GHCJS works, but generates 5mb JavaScript files.

This is what I meant when I said "by virtue of support for existing libraries". js_of_ocaml translates compiled bytecode and can therefore make any pure OCaml library work in JavaScript without recompilation.