#10599: Template Haskell doesn't allow `newName "type"` -------------------------------------+------------------------------------- Reporter: meteficha | Owner: goldfire Type: bug | Status: new Priority: high | Milestone: 7.12.1 Component: Template Haskell | Version: 7.10.2-rc2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: None/Unknown | Unknown/Multiple Blocked By: | Test Case: Related Tickets: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- Comment (by GregWeber):
So when you say newName "type", the variable's name really is type, but because it comes from newName, GHC prints it specially, as it's different from any other variable named type. So what you're trying to do -- create a variable named type -- is objectionable
This isn't the goal here. If it was, `mkName` would be used.
It seems to me that we should be closing up the cases where type can be used as a name, not opening more of these holes. It would be quite confusing to the user if they end up with a situation where a they see an export named type, find that it can be imported without trouble if qualified, and then try to define another similarly named definition without of TH, only to find that they get a syntax error.
Again, "type" is not being used for a name but instead to seed a new name From a TH user perspective it seems that in 7.10 `newName` has become a leaky abstraction where I am forced to understand how GHC is internalizing these names in a way that is different than what is printed out. As a library author, I can certainly work around this. But it isn't something I would think to test and I only found out about it when a user reported that their program stopped working on 7.10. So at this point there is no way for us to quantify the breakage it would cause. I would expect it to be fairly rare that a name gets into a TH function that is reserved as an identifier: for persistent this happens because it later adds a record field prefix to the name before generating a record field. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10599#comment:6 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler