1. 08 May, 2014 1 commit
  2. 21 Jun, 2013 1 commit
    • eir@cis.upenn.edu's avatar
      Revise implementation of overlapping type family instances. · 569b2652
      eir@cis.upenn.edu authored
      This commit changes the syntax and story around overlapping type
      family instances. Before, we had "unbranched" instances and
      "branched" instances. Now, we have closed type families and
      open ones.
      
      The behavior of open families is completely unchanged. In particular,
      coincident overlap of open type family instances still works, despite
      emails to the contrary.
      
      A closed type family is declared like this:
      > type family F a where
      >   F Int = Bool
      >   F a   = Char
      The equations are tried in order, from top to bottom, subject to
      certain constraints, as described in the user manual. It is not
      allowed to declare an instance of a closed family.
      569b2652
  3. 04 Feb, 2013 1 commit
    • chak@cse.unsw.edu.au.'s avatar
      Fix tidying of vectorised code · 82a30378
      chak@cse.unsw.edu.au. authored
      * We need to keep the vectorised version of a variable alive while the original is alive.
      * This implies that the vectorised version needs to get into the iface if the original appears in an unfolding.
      82a30378
  4. 22 Dec, 2012 1 commit
    • eir@cis.upenn.edu's avatar
      Implement overlapping type family instances. · 8366792e
      eir@cis.upenn.edu authored
      An ordered, overlapping type family instance is introduced by 'type
      instance
      where', followed by equations. See the new section in the user manual
      (7.7.2.2) for details. The canonical example is Boolean equality at the
      type
      level:
      
      type family Equals (a :: k) (b :: k) :: Bool
      type instance where
        Equals a a = True
        Equals a b = False
      
      A branched family instance, such as this one, checks its equations in
      order
      and applies only the first the matches. As explained in the note
      [Instance
      checking within groups] in FamInstEnv.lhs, we must be careful not to
      simplify,
      say, (Equals Int b) to False, because b might later unify with Int.
      
      This commit includes all of the commits on the overlapping-tyfams
      branch. SPJ
      requested that I combine all my commits over the past several months
      into one
      monolithic commit. The following GHC repos are affected: ghc, testsuite,
      utils/haddock, libraries/template-haskell, and libraries/dph.
      
      Here are some details for the interested:
      
      - The definition of CoAxiom has been moved from TyCon.lhs to a
        new file CoAxiom.lhs. I made this decision because of the
        number of definitions necessary to support BranchList.
      
      - BranchList is a GADT whose type tracks whether it is a
        singleton list or not-necessarily-a-singleton-list. The reason
        I introduced this type is to increase static checking of places
        where GHC code assumes that a FamInst or CoAxiom is indeed a
        singleton. This assumption takes place roughly 10 times
        throughout the code. I was worried that a future change to GHC
        would invalidate the assumption, and GHC might subtly fail to
        do the right thing. By explicitly labeling CoAxioms and
        FamInsts as being Unbranched (singleton) or
        Branched (not-necessarily-singleton), we make this assumption
        explicit and checkable. Furthermore, to enforce the accuracy of
        this label, the list of branches of a CoAxiom or FamInst is
        stored using a BranchList, whose constructors constrain its
        type index appropriately.
      
      I think that the decision to use BranchList is probably the most
      controversial decision I made from a code design point of view.
      Although I provide conversions to/from ordinary lists, it is more
      efficient to use the brList... functions provided in CoAxiom than
      always to convert. The use of these functions does not wander far
      from the core CoAxiom/FamInst logic.
      
      BranchLists are motivated and explained in the note [Branched axioms] in
      CoAxiom.lhs.
      
      - The CoAxiom type has changed significantly. You can see the new
        type in CoAxiom.lhs. It uses a CoAxBranch type to track
        branches of the CoAxiom. Correspondingly various functions
        producing and consuming CoAxioms had to change, including the
        binary layout of interface files.
      
      - To get branched axioms to work correctly, it is important to have a
        notion
        of type "apartness": two types are apart if they cannot unify, and no
        substitution of variables can ever get them to unify, even after type
      family
        simplification. (This is different than the normal failure to unify
      because
        of the type family bit.) This notion in encoded in tcApartTys, in
      Unify.lhs.
        Because apartness is finer-grained than unification, the tcUnifyTys
      now
        calls tcApartTys.
      
      - CoreLinting axioms has been updated, both to reflect the new
        form of CoAxiom and to enforce the apartness rules of branch
        application. The formalization of the new rules is in
        docs/core-spec/core-spec.pdf.
      
      - The FamInst type (in types/FamInstEnv.lhs) has changed
        significantly, paralleling the changes to CoAxiom. Of course,
        this forced minor changes in many files.
      
      - There are several new Notes in FamInstEnv.lhs, including one
        discussing confluent overlap and why we're not doing it.
      
      - lookupFamInstEnv, lookupFamInstEnvConflicts, and
        lookup_fam_inst_env' (the function that actually does the work)
        have all been more-or-less completely rewritten. There is a
        Note [lookup_fam_inst_env' implementation] describing the
        implementation. One of the changes that affects other files is
        to change the type of matches from a pair of (FamInst, [Type])
        to a new datatype (which now includes the index of the matching
        branch). This seemed a better design.
      
      - The TySynInstD constructor in Template Haskell was updated to
        use the new datatype TySynEqn. I also bumped the TH version
        number, requiring changes to DPH cabal files. (That's why the
        DPH repo has an overlapping-tyfams branch.)
      
      - As SPJ requested, I refactored some of the code in HsDecls:
      
       * splitting up TyDecl into SynDecl and DataDecl, correspondingly
         changing HsTyDefn to HsDataDefn (with only one constructor)
      
       * splitting FamInstD into TyFamInstD and DataFamInstD and
         splitting FamInstDecl into DataFamInstDecl and TyFamInstDecl
      
       * making the ClsInstD take a ClsInstDecl, for parallelism with
         InstDecl's other constructors
      
       * changing constructor TyFamily into FamDecl
      
       * creating a FamilyDecl type that stores the details for a family
         declaration; this is useful because FamilyDecls can appear in classes
      but
         other decls cannot
      
       * restricting the associated types and associated type defaults for a
       * class
         to be the new, more restrictive types
      
       * splitting cid_fam_insts into cid_tyfam_insts and cid_datafam_insts,
         according to the new types
      
       * perhaps one or two more that I'm overlooking
      
      None of these changes has far-reaching implications.
      
      - The user manual, section 7.7.2.2, is updated to describe the new type
        family
        instances.
      8366792e
  5. 15 Dec, 2012 1 commit
  6. 12 Dec, 2012 1 commit
  7. 05 Dec, 2012 1 commit
  8. 12 Jun, 2012 3 commits
  9. 07 May, 2012 1 commit
  10. 25 Apr, 2012 1 commit
  11. 18 Dec, 2011 1 commit
  12. 25 Nov, 2011 1 commit
  13. 17 Nov, 2011 1 commit
  14. 09 Nov, 2011 1 commit
  15. 04 Nov, 2011 1 commit
  16. 31 Oct, 2011 1 commit
  17. 10 Oct, 2011 1 commit
  18. 21 Sep, 2011 1 commit
    • Simon Marlow's avatar
      Add support for all top-level declarations to GHCi · 3db75724
      Simon Marlow authored
        This is work mostly done by Daniel Winograd-Cort during his
        internship at MSR Cambridge, with some further refactoring by me.
      
      This commit adds support to GHCi for most top-level declarations that
      can be used in Haskell source files.  Class, data, newtype, type,
      instance are all supported, as are Type Family-related declarations.
      
      The current set of declarations are shown by :show bindings.  As with
      variable bindings, entities bound by newer declarations shadow earlier
      ones.
      
      Tests are in testsuite/tests/ghci/scripts/ghci039--ghci054.
      Documentation to follow.
      3db75724
  19. 10 Sep, 2011 1 commit
  20. 24 Aug, 2011 2 commits
  21. 18 Aug, 2011 1 commit
  22. 21 Jul, 2011 1 commit
    • Simon Peyton Jones's avatar
      Change loop breaker terminology · e815d4b1
      Simon Peyton Jones authored
      We used to have "loop breaker" and "non-rule loop breaker", but
      the unqualified version in particualr was pretty confusing.  So
      now we have "strong loop breaker" and "weak loop breaker";
      comments in BasicTypes and OccurAnal.
      e815d4b1
  23. 30 Jun, 2011 1 commit
  24. 13 Jun, 2011 1 commit
  25. 19 Apr, 2011 1 commit
    • Simon Peyton Jones's avatar
      This BIG PATCH contains most of the work for the New Coercion Representation · fdf86568
      Simon Peyton Jones authored
      See the paper "Practical aspects of evidence based compilation in System FC"
      
      * Coercion becomes a data type, distinct from Type
      
      * Coercions become value-level things, rather than type-level things,
        (although the value is zero bits wide, like the State token)
        A consequence is that a coerion abstraction increases the arity by 1
        (just like a dictionary abstraction)
      
      * There is a new constructor in CoreExpr, namely Coercion, to inject
        coercions into terms
      fdf86568
  26. 26 Jan, 2011 1 commit
  27. 05 Mar, 2011 1 commit
    • chak@cse.unsw.edu.au.'s avatar
      Completed the implementation of VECTORISE SCALAR · 2db562c7
      chak@cse.unsw.edu.au. authored
      - The pragma {-# VECTORISE SCALAR foo #-} marks 'foo' as a
        scalar function for for vectorisation and generates a
        vectorised version by applying 'scalar_map' and friends.
      - The set of scalar functions is not yet emitted into
        interface files.  This will be added in a subsequent
        patch via 'VectInfo'.
      2db562c7
  28. 20 Feb, 2011 1 commit
    • chak@cse.unsw.edu.au.'s avatar
      Added a VECTORISE pragma · f2aaae97
      chak@cse.unsw.edu.au. authored
      - Added a pragma {-# VECTORISE var = exp #-} that prevents
        the vectoriser from vectorising the definition of 'var'.
        Instead it uses the binding '$v_var = exp' to vectorise
        'var'.  The vectoriser checks that the Core type of 'exp'
        matches the vectorised Core type of 'var'.  (It would be
        quite complicated to perform that check in the type checker
        as the vectorisation of a type needs the state of the VM
        monad.)
      - Added parts of a related VECTORISE SCALAR pragma
      - Documented -ddump-vect
      - Added -ddump-vt-trace
      - Some clean up
      f2aaae97
  29. 15 Feb, 2011 1 commit
  30. 14 Feb, 2011 1 commit
  31. 09 Feb, 2011 1 commit
  32. 27 Oct, 2010 1 commit
    • Simon Marlow's avatar
      Refactoring and tidyup of HscMain and related things (also fix #1666) · 94bf0d36
      Simon Marlow authored
      While trying to fix #1666 (-Werror aborts too early) I decided to some
      tidyup in GHC/DriverPipeline/HscMain.
      
       - The GhcMonad overloading is gone from DriverPipeline and HscMain
         now.  GhcMonad is now defined in a module of its own, and only
         used in the top-level GHC layer.  DriverPipeline and HscMain
         use the plain IO monad and take HscEnv as an argument.
      
       - WarnLogMonad is gone.  printExceptionAndWarnings is now called
         printException (the old name is deprecated).  Session no longer
         contains warnings.
      
       - HscMain has its own little monad that collects warnings, and also
         plumbs HscEnv around.  The idea here is that warnings are collected
         while we're in HscMain, but on exit from HscMain (any function) we
         check for warnings and either print them (via log_action, so IDEs
         can still override the printing), or turn them into an error if
         -Werror is on.
      
       - GhcApiCallbacks is gone, along with GHC.loadWithLogger.  Thomas
         Schilling told me he wasn't using these, and I don't see a good
         reason to have them.
      
       - there's a new pure API to the parser (suggestion from Neil Mitchell):
            parser :: String
                   -> DynFlags
                   -> FilePath
                   -> Either ErrorMessages (WarningMessages, 
                                            Located (HsModule RdrName))
      94bf0d36
  33. 19 Oct, 2010 1 commit
  34. 15 Sep, 2010 1 commit
  35. 09 Sep, 2010 1 commit
  36. 08 Sep, 2010 2 commits