#4020: Please consider adding support for local type synonyms -------------------------------------+------------------------------------- Reporter: nr | Owner: (none) Type: feature request | Status: new Priority: low | Milestone: Component: Compiler (Type | Version: 6.12.2 checker) | Resolution: | Keywords: type synonym Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by AntC): Replying to [comment:18 ezyang]:
Yeah, local type synonyms are probably the least controversial
Thanks Edward, but I see no controversy. Only the usual questions about what are the use cases/benefits? what does it provide that can't be written now/only written clumsily? how does it work? what complications does the user need to understand? what complications does the compiler need to understand?
of "make global things possible locally" proposals. There are pretty clear semantics for how it works in all cases.
Then it should be easy for someone to write up a proposal on github. I've seen plenty of "make global things possible locally" proposals. None of them have given a coherent explanation for how the local thing is to behave when something containing it or mentioning it or bound to it gets exported globally. (For example with class instances; that's why Wadler made them global despite his initial proposal making them let-bound.) -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/4020#comment:20 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler