[GHC] #13347: Abstract classes in hs-boot should not be treated as injective
GHC
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Mon Feb 27 03:49:54 UTC 2017
#13347: Abstract classes in hs-boot should not be treated as injective
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Reporter: ezyang | Owner: (none)
Type: bug | Status: new
Priority: low | Milestone:
Component: Compiler | Version: 8.1
(Type checker) |
Keywords: hs-boot | Operating System: Unknown/Multiple
Architecture: | Type of failure: None/Unknown
Unknown/Multiple |
Test Case: | Blocked By:
Blocking: | Related Tickets:
Differential Rev(s): | Wiki Page:
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They could be implemented by a newtype (see `mkClass`), making them non-
injective.
Fortunately, this doesn't seem to cause any unsoundness, because the
*constructor* for the newtype corresponding to a class is never in scope,
so we are never allowed to unwrap "class newtypes". Phew!
--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13347>
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