Update documentation around non-capturing monadic bind for Action

src/Development/Shake/Internal/Core/Types.hs

@@ -60,8 +60,14 @@ import Prelude
 --   To raise an exception call 'error', 'fail' or @'liftIO' . 'throwIO'@.
 --
 --   The 'Action' type is both a 'Monad' and 'Applicative'. Anything that is depended upon applicatively
---   will have its dependencies run in parallel. For example @'need' [\"a\"] *> 'need [\"b\"]@ is equivalent
---   to @'need' [\"a\", \"b\"]@.
+--   will have its dependencies run in parallel. For example,
+--   @'Development.Shake.Internal.Rules.File.need' [\"a\"] '*>' 'Development.Shake.Internal.Rules.File.need' [\"b\"]@
+--   is equivalent to @'need' [\"a\", \"b\"]@.
+--
+--   Note that since Shake 0.18, the non-capturing monadic bind ('>>') will also run its dependencies in parallel.
+--   For example,
+--   @'Development.Shake.Internal.Rules.File.need' [\"a\"] '>>' 'Development.Shake.Internal.Rules.File.need' [\"b\"]@
+--   is also equivalent to @'Development.Shake.Internal.Rules.File.need' [\"a\", \"b\"]@.
 newtype Action a = Action {fromAction :: RAW ([String],[Key]) [Value] Global Local a}
     deriving (Functor, Applicative, Monad, MonadIO, Typeable, Semigroup, Monoid, MonadFail)
 

src/Development/Shake/Internal/Rules/File.hs

@@ -371,8 +371,13 @@ fileForward help act = addUserRule $ FileRule help $ fmap ModeForward . act
 --     'Development.Shake.cmd' \"rot13\" [src] \"-o\" [out]
 -- @
 --
---   Usually @need [foo,bar]@ is preferable to @need [foo] >> need [bar]@ as the former allows greater
---   parallelism, while the latter requires @foo@ to finish building before starting to build @bar@.
+--   Note that the following expressions are all equivalent. @foo@ and @bar@ are built in parallel:
+--
+--   - @need [foo,bar]@
+--   - @need [foo] '*>' need [bar]@
+--   - @need [foo] '>>' need [bar]@
+--
+--   In this situation, @need [foo, bar]@ is preferable, since the parallelism is the most obvious.
 --
 --   This function should not be called with wildcards (e.g. @*.txt@ - use 'getDirectoryFiles' to expand them),
 --   environment variables (e.g. @$HOME@ - use 'getEnv' to expand them) or directories (directories cannot be