• simonpj@microsoft.com's avatar
    Fix a deriving bug, arising from recent refactoring · 66f73ee4
    simonpj@microsoft.com authored
    This one is a hangover from something I did a month or two ago, but
    didn't get quite right.  tcSimplifyDefault should not check for no-instances;
    instead the checkValidInstance in TcDeriv does so.
    
    Conal's DeepArrow needs this fix.  Test is drv015.
    
    66f73ee4
TcSimplify.lhs 88.5 KB