[GeZe]

If you are looking for a syntax closer to Haskell's, you can take a look at LiveScript (http://livescript.net/)

eg.

    getUserFriends = (userName) ->
      user <- findUser userName
      friends <- findFriends user
      ...

Specifically, the section on "backcalls": http://livescript.net/#backcalls

[damncabbage]

If you are looking for Haskell, you can take a look at Fay (https://github.com/faylang/fay/wiki).

[chx]

What about Haste? https://github.com/valderman/haste-compiler

[seanmcdirmid]

Back calls look like array programming gone even crazier. Was live script inspired by APL?