• Simon Peyton Jones's avatar
    Fix an obscure but terrible bug in the simplifier (Trac #9567) · b8392ae7
    Simon Peyton Jones authored
    The issue was that contInputType simply gave the wrong answer
    for type applications.
    
    There was no way to fix contInputType; it just didn't have enough
    information.  So I did this:
    
    * Split the ApplyTo constructor of SimplUtils.SimplCont into
          ApplyToVal
          ApplyToTy
      I used record syntax for them; we should do this for some
      of the other constructors too.
    
    * The latter carries a sc_hole_ty, which is the type of the
      continuation's "hole"
    
    * Maintaining this type meant that I had do to something
      similar for SimplUtils.ArgSpec.
    
    * I renamed contInputType to contHoleType for consistency.
    
    * I did a bit of refactoring around the call to tryRules
      in Simplify, which was jolly confusing before.
    
    The resulting code is quite nice now.  And it has the additional
    merit that it works.
    
    The tests are simply tc124 and T7891 with -O enabled.
    b8392ae7
Simplify.hs 115 KB