Something like Haskell seems like a good fit for the brevity of working with sequences using higher order functions, but maybe the type system is too verbose...

Something like Haskell seems like a good fit for the brevity of working with sequences using higher order functions, but maybe the type system is too verbose... I'm sure there's some better candidates, but it'd be a nice start and maybe an excuse to look at the work of that one person who turned a Haskell dialect that compiles to javascript into a fulltime job.