tcfail001.hs:9: Warning:
- Duplicated class assertion `A a' in the context: (A a, A a)
+ Duplicate class assertion `A a' in the context: (A a, A a) =>
tcfail001.hs:9:
- Couldn't match the type `[a]' against `aqv -> aqw'
- Expected: [a]
- Inferred: aqv -> aqw
+ Couldn't match `[a]' against `$0 -> $1'
+ Expected type: [a]
+ Inferred type: $0 -> $1
In an equation for function `op': op [] = []
In the definition for method `op'