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  • Glasgow Haskell CompilerGlasgow Haskell Compiler
  • GHCGHC
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  • #7148
Closed
Open
Issue created Aug 15, 2012 by Carter Schonwald@carterDeveloper

generalized newtype and type families is unsound

the code from http://joyoftypes.blogspot.com/2012/08/generalizednewtypederiving-is.html type checks in the release candidate

also see discussion here http://www.reddit.com/r/haskell/comments/y8kca/generalizednewtypederiving_is_very_very_unsafe/

(punch line: the generalized newtype deriving + type families or gadts allows users to write unsafeCoerce etc)

perhaps a simple near term solution is to have any module using generalized new type deriving be inferred to be unsafe by default?

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Version 7.6.1-rc1
Type Bug
TypeOfFailure OtherFailure
Priority normal
Resolution Unresolved
Component Compiler
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