#13558: Inconsistency in `CoreUtils.exprIsOk` -------------------------------------+------------------------------------- Reporter: simonpj | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Consider {{{ f1 = \x y -> let t = case x of True -> let v = Just y in (v, v) False -> (Nothing, Nothing) in \w -> t f2 = \x y -> let t = case x of True -> (Just y, Just y) False -> (Nothing, Nothing) in \w -> t }}} We give `f1` arity 1, but `f2` gets arity 2. That's bizarre, because all we've done is turn a `let` into a function application. Reason: in `CoreUtils.exprIsOk`, we recursively apply `go` in the `App` case, but we fail unconditionally in the `Let` case. That is simply inconsistent, and it bit me when trying something else. Incidentally `exprIsOk` is badly named. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13558 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler