Tsuyoshi Ito
How can I use combinators like repeat, which takes a plain function as an argument, in the arrow notation in a more readable way? Or am I trying to do an impossible thing?
To answer your question: Arrow notation has no support for what you want, so if you stick with it you will have to write the inner proc explicitly. However: The code may look much nicer, if you use applicative style for the outer computation using Applicative, Category and Profunctor [1]: test2 :: MyArr [Double] String test2 = repeat 100 rmap . liftA3 (,,) id y z where y = arr func1 z = job1 rmap i = lmap (\(xs, y, z) -> xs !! i + y + z) (job3 (i * 2)) If you prefer, you can use arrow notation for the inner computation. [1]: http://hackage.haskell.org/package/profunctors Greets, Ertugrul -- Not to be or to be and (not to be or to be and (not to be or to be and (not to be or to be and ... that is the list monad.