can't declare instance for type synonim
Trying to load into GHCi simple program (in attached
file) I receive error stating I can declare class instances
only for types defined using "data". I beleive it is a bug
because Hugs handles this situation normally.
Error message:
/igor/tst.hs:1:
No instance for `Eq (Stack -> Stack)'
When deriving the `Eq' instance for type `Object'
/igor/tst.hs:1:
No instance for `Show (Stack -> Stack)'
When deriving the `Show' instance for type `Object'
/igor/tst.hs:4:
Illegal instance declaration for `Eq Operator'
(The instance type must be of form (T a b c)
where T is not a synonym, and a,b,c are distinct
type variables)
In the instance declaration for `Eq Operator'
/igor/tst.hs:6:
Illegal instance declaration for `Show Operator'
(The instance type must be of form (T a b c)
where T is not a synonym, and a,b,c are distinct
type variables)
In the instance declaration for `Show Operator'
Trac metadata
Trac field |
Value |
Version |
None |
Type |
Bug |
TypeOfFailure |
OtherFailure |
Priority |
normal |
Resolution |
ResolvedRejected |
Component |
Compiler (Type checker) |
Test case |
|
Differential revisions |
|
BlockedBy |
|
Related |
|
Blocking |
|
CC |
|
Operating system |
|
Architecture |
|