deriving for GRose
GHC 6.6 used to be happy with the program below provided that i use "-fglasgow-exts -fallow-undecidable-instances"
data GRose ff a = GRose a (ff (GRose ff a))
The same program does NOT work with GHC 6.8, 6.8.1 and 6.8.2, even if I use the options "-fglasgow-exts -XUndecidableInstances". This is the error I get:
No instance for (Show (ff (GRose ff a)))
arising from the 'deriving' clause of a data type declaration
at domotest.hs:2:0-56
Possible fix:
add an instance declaration for (Show (ff (GRose ff a)))
When deriving the instance for (Show (GRose ff a))
Trac metadata
Trac field | Value |
---|---|
Version | 6.8.2 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Compiler |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | |
Operating system | |
Architecture |