#10875: Unexpected defaulting of partial type signatures and inconsistent behaviour when -fdefer-typed-holes is set. -------------------------------------+------------------------------------- Reporter: holzensp | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.2 Resolution: | Keywords: | PartialTypeSignatures TypedHoles Operating System: MacOS X | Architecture: x86_64 Type of failure: Incorrect | (amd64) warning at compile-time | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Revisions: -------------------------------------+------------------------------------- Comment (by simonpj): Interesting examples, thank you! As it happens I am in mid-flight on a significant refactoring of the wildcard implementation, so I'd like to park these examples and come back to them when I commit. It has turned out to be a much bigger job than I anticipated, I'm afraid. Just on the narrow question of defaulting, I think it's not unreasonable that wildcards don't affect type-class defaulting (i.e. in ambiguous cases, choose a particular type to fix the type, see [https://www.haskell.org/onlinereport/haskell2010/haskellch4.html#x10-750004.... 4.3.4 in the language definition]. Wouldn't people complain if adding wildcards changed the typing rules? Can you specify ''precisely'' what the new defaulting rules would then be? Simon -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10875#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler