defining instance in GHCi leads to duplicated instances
Bizarre:
claude@jazzyjeff:~$ cat Foo.hs
module Foo where
data Foo = Foo
instance Num Foo where
claude@jazzyjeff:~$ ~/opt/ghc-7.4/bin/ghci -w Foo.hs
GHCi, version 7.4.0.20120119: http://www.haskell.org/ghc/ :? for help
Loading package ghc-prim ... linking ... done.
Loading package integer-gmp ... linking ... done.
Loading package base ... linking ... done.
[1 of 1] Compiling Foo ( Foo.hs, interpreted )
Ok, modules loaded: Foo.
*Foo> :info Foo
data Foo = Foo -- Defined at Foo.hs:2:6
instance Num Foo -- Defined at Foo.hs:3:10
*Foo> instance Fractional Foo where
*Foo> :info Foo
data Foo = Foo -- Defined at Foo.hs:2:6
instance Fractional Foo -- Defined at <interactive>:3:10
instance Num Foo -- Defined at Foo.hs:3:10
instance Num Foo -- Defined at Foo.hs:3:10
I get an extra Num instance (where from? same source location??), which causes overlapping problems.
Trac metadata
Trac field | Value |
---|---|
Version | 7.4.1-rc1 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | GHCi |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | claudiusmaximus@goto10.org |
Operating system | |
Architecture |