#14370: non-deferred typed hole despite -fdefer-typed-holes -------------------------------------+------------------------------------- Reporter: int-e | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Incorrect | Unknown/Multiple error/warning at compile-time | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by int-e): Replying to [comment:1 monoidal]:
Does [https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/glasgow_exts... #deferred-type-errors-in-ghci this] answer your question?
Yes and no. I still believe that the behavior is surprising, but this means it's a feature, not a bug (I don't care enough to argue otherwise). Btw, from this section I would conclude that `length [r]` should also produce an error, since both typed holes and out of scope variables fall under the headline [https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/glasgow_exts... #deferring-type-errors-to-runtime Deferring type errors to runtime]. In any case it appears that the documentation can be improved a bit. * clarify in [https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/glasgow_exts... #deferred-type-errors-in-ghci Deferred type errors in GHCi] that this applies to type checking errors (including typed holes) but not to name resolution (out of scope variables) * I didn't find the GHCi exception when reading [https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/glasgow_exts... #typed-holes Typed Holes] so a forward reference may be helpful * The description of [https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/using- warnings.html#ghc-flag--fdefer-type-errors -fdefer-type-errors] should mention that it implies -fdefer-out-of-scope-variables -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14370#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler