Bas van Dijk
Do we still need idiom brackets if we have ApplicativeDo?
I think they solve different things. ApplicativeDo is a nice extension when I need to run n different effectful computations, but either use m < n results (that is, emulating the <* and *> operators), and/or if I need to return the results in a different order. For example: do a <- x b <- y c <- z (b, a) That's going to be a pain to write using idiom brackets: (| (\a b _ -> (b, a)) x y z |) However, for the common case where you do want to apply a function to the result of all effectful computations, then ApplicativeDo just forces you to introduce new symbol names: do x' <- x y' <- y z' <- z f x' y' z' I'm against this not just due to the extra amount of typing, but choosing names is often an unnecessary cognitive burden - I've often already used up the "obvious" name, and now I'm forced to come up with another set of names, unless I want to live with shadowing warnings (not an option, I use -Werror). - Ollie