When type classes are redefined in GHCi bindings that use old instances are still accessible
I found the following behavior surprising:
GHCi, version 8.0.1: http://www.haskell.org/ghc/ :? for help
Loaded GHCi configuration from /tmp/ghci7261/ghci-script
Prelude> class Foo a where { foo :: a -> Int }
Prelude> instance Foo () where { foo _ = 1 }
Prelude> f = foo ()
Prelude> class Foo a where { foo :: a -> IO () }
Prelude> f
1
Foo
is redefined but f
which uses a now illegal instance of Foo
is still accessible. I would have expected that any bindings that use the old foo
(or have the old foo
in their call graph) would be cleared.
Trac metadata
Trac field | Value |
---|---|
Version | 8.0.1 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | GHCi |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | |
Operating system | |
Architecture |