#13875: ApplicativeDo desugaring is lazier than standard desugaring -------------------------------------+------------------------------------- Reporter: dfeuer | Owner: simonmar Type: bug | Status: new Priority: high | Milestone: 8.2.1 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): Yet another few thoughts. This is a situation that could be improved offering, in addition, separate `ado` syntax. Such syntax would offer deeply-lazy-always pattern matching, prohibit inappropriate bangs, and throw an error if desugaring would require `>>=`. Along with setting laziness appropriately, this would allow the user to declare that they expect applicative optimizations to kick in, even when a monad is actually available. While I'm mentioning idle thoughts: monad comprehension syntax seems to handle the `pure`/`return`/`pure $`/whatever issue a lot more cleanly than anything `do`-like. Has anyone considered applicative comprehensions? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13875#comment:6 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler