2 "tcfail023.hs", line 8: Duplicate/overlapping instances:
3 class "A", type "B"; at "tcfail023.hs", line 8 and "tcfail023.hs", line 11
5 "tcfail023.hs", line 11:
6 Couldn't match type "Bool" against "B".
7 Inside a function binding:
9 Fail: Compilation errors found
11 ghc: execution of the Haskell compiler had trouble