[Haskell-cafe] can the default instances in GHC be recompiled with
jason.dusek at gmail.com
Mon Aug 25 15:00:07 EDT 2008
Per the GHC manual section on instance overlap:
If an instance declaration is compiled without
-XOverlappingInstances, then that instance can never be
overlapped. This could perhaps be inconvenient.
It is inconvenient for certain things. If I want to declare a
special `instance Show [MyType] where...` I am out of luck.
However, the solution need not involve a change to the way
instances are handled -- if all the `GHC.*` instances were
compiled with overlapping instances, I'd be able to declare my
Is there a substantial barrier, either theoretical or
practical, to recompiling GHC this way?
|...GHC manual section...|
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