• Simon Peyton Jones's avatar
    Apply the right substitution in ty-fam improvement · 2b64e926
    Simon Peyton Jones authored
    Trac #13135 showed that we were failing to apply the
    correct substitution to the un-substituted tyvars during
    type-family improvement using injectivity.  Specifically
    in TcInteractlinjImproveEqns we need to use instFlexiX.
    
    An outright bug, easy to fix.
    
    Slight refactoring along the way.  The quantified tyars of the axiom are
    readily to hand; we don't need to take the free tyvars of the LHS
    2b64e926
TcSMonad.hs 112 KB