Combine results within a monad without do

I have a snippet of code which can abstractly be described as this:

foobar = do
  foo <- getFoo
  bar <- getBar
  return $ foo ++ bar

It feels like there must be a nice way to combine foo and bar that doesn’t require four lines of do notation – some infix operator I can apply directly to getFoo and getBar maybe (perhaps specifying (++) as a combining function, but given that the results are a Monoid I shouldn’t really have to…) – but I can’t find anything like this.

I searched Hoogle for things like Monad m => (a -> a -> a) -> m a -> m a -> m a and Monad m, Monoid a => m a -> m a -> m a but came up empty.

Is there a combine function/operator like this?

>Solution :

Applicative notation is rather popular:

foobar = (++) <$> getFoo <*> getBar

This naturally extends to n-ary functions. The expression f <$> action1 <*> ... <*> actionN works under the following hypotheses:

-- F is any applicative (including monads)
actioni :: F ti   -- for i in 1..N
f :: t1 -> t2 -> ... -> tN -> r

in which case

f <$> action1 <*> ... <*> actionN :: F r