Applicative do-notation desugaring preserves the original semantics,
#13875: ApplicativeDo desugaring is lazier than standard desugaring -------------------------------------+------------------------------------- Reporter: dfeuer | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.4.1 Component: Compiler | Version: 8.3 Resolution: | Keywords: ApplicativeDo Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: Other | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by dfeuer): Note that the documentation indicates provided that the `Applicative` instance satisfies `<*> = ap` and `pure = return` (these are true of all the common monadic types). Thus, you can normally turn on `-XApplicativeDo` without fear of breaking your program. There is one pitfall to watch out for; see Things to watch out for. This is simply not true at the moment. The "Things to watch out for" section is unrelated. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13875#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler