1. 12 Jan, 2014 1 commit
  2. 22 Nov, 2013 1 commit
  3. 18 Nov, 2013 2 commits
  4. 01 Oct, 2013 1 commit
  5. 20 Sep, 2013 1 commit
  6. 02 Aug, 2013 1 commit
  7. 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
  8. 19 Jun, 2013 1 commit
  9. 09 May, 2013 1 commit
  10. 24 Apr, 2013 1 commit
  11. 13 Feb, 2013 1 commit
  12. 28 Jan, 2013 2 commits
    • Simon Peyton Jones's avatar
      Pure refactoring · f1fa6eb2
      Simon Peyton Jones authored
      * Move tidyType and friends from TcType to TypeRep
        (It was always wrong to have it in TcType.)
      
      * Move mkCoAxBranch and friends from FamInst to Coercion
      
      * Move pprCoAxBranch and friends from FamInstEnv to Coercion
      
      No change in functionality, though there might be a little
      wibble in error message output, because I combined two different
      functions both called pprCoAxBranch!
      f1fa6eb2
    • Simon Peyton Jones's avatar
      More refactoring of FamInst/FamInstEnv; finally fixes Trac #7524 · a98e51ec
      Simon Peyton Jones authored
      Quite a bit of tidying up here; the fix to #7524 is actually
      only a small part.
      
      * Be fully clear that the cab_tvs in a CoAxBranch are not
        fresh.  See Note [CoAxBranch type variables] in CoAxiom.
      
      * Use CoAxBranch to replace the ATDfeault type in Class.
        CoAxBranch is perfect here.  This change allowed me to
        delete quite a bit of boilerplate code, including the
        corresponding IfaceSynType.
      
      * Tidy up the construction of CoAxBranches, and when FamIntBranch is
        freshened.  The latter onw happens only in FamInst.newFamInst.
      
      * Tidy the tyvars of a CoAxBranch when we build them, done in
        FamInst.mkCoAxBranch.  See Note [Tidy axioms when we build them]
        in that module.  This is what fixes #7524.
      
      Much niceer now.
      a98e51ec
  13. 25 Jan, 2013 1 commit
    • Simon Peyton Jones's avatar
      Refactor and improve the promotion inference · 09ff0e0d
      Simon Peyton Jones authored
      It should be the case that either an entire mutually recursive
      group of data type declarations can be promoted, or none of them.
      It's really odd to promote some data constructors of a type but
      not others. Eg
        data T a = T1 a | T2 Int
      Here T1 is sort-of-promotable but T2 isn't (becuase Int isn't
      promotable).
      
      This patch makes it all-or-nothing. At the same time I've made
      the TyCon point to its promoted cousin (via the tcPromoted field
      of an AlgTyCon), as well as vice versa (via the ty_con field of
      PromotedTyCon).
      
      The inference for the group is done in TcTyDecls, the same place
      that infers which data types are recursive, another global question.
      09ff0e0d
  14. 05 Jan, 2013 1 commit
    • eir@cis.upenn.edu's avatar
      Refactor invariants for FamInsts. · 5765248b
      eir@cis.upenn.edu authored
      This commit mirrors work done in the commit for ClsInsts, 5efe9b...
      
      Specifically:
      - All FamInsts have *fresh* type variables. So, no more freshness work
      in addLocalFamInst
      
      Also:
      - Some pretty-printing code around FamInsts was cleaned up a bit
      This caused location information to be added to CoAxioms and index
      information to be added to FamInstBranches.
      5765248b
  15. 01 Jan, 2013 1 commit
    • Simon Peyton Jones's avatar
      Refactor the invariants for ClsInsts · 5efe9b11
      Simon Peyton Jones authored
      We now have the invariant for a ClsInst that the is_tvs field
      is always completely fresh type variables. See
      Note [Template tyvars are fresh] in InstEnv.
      
      (Previously we frehened them when extending the instance environment,
      but that seems messier because it was an invariant only when the
      ClsInst was in an InstEnv.  Moreover, there was an invariant that
      thet tyvars of the DFunid in the ClsInst had to match, and I have
      removed that invariant altogether; there is no need for it.)
      
      Other changes I made at the same time:
      
       * Make is_tvs into a *list*, in the right order for the dfun type
         arguments.  This removes the wierd need for the dfun to have the
         same tyvars as the ClsInst template, an invariant I have always
         hated. The cost is that we need to make it a VarSet when matching.
         We could cache an is_tv_set instead.
      
       * Add a cached is_cls field to the ClsInst, to save fishing
         the Class out of the DFun.  (Renamed is_cls to is_cls_nm.)
      
       * Make tcSplitDFunTy return the dfun args, not just the *number*
         of dfun args
      
       * Make InstEnv.instanceHead return just the *head* of the
         instance declaration.  Add instanceSig to return the whole
         thing.
      5efe9b11
  16. 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
  17. 10 Dec, 2012 1 commit
  18. 07 Dec, 2012 1 commit
  19. 21 Sep, 2012 1 commit
  20. 21 Jun, 2012 1 commit
    • jpm@cs.ox.ac.uk's avatar
      Allow deriving Generic1 · 156ec95a
      jpm@cs.ox.ac.uk authored
      This completes the support for generic programming introduced
      in GHC 7.2. Generic1 allows defining generic functions that
      operate on type containers, such as `fmap`, for instance.
      
      Along the way we have fixed #5936 and #5939, allowing
      deriving Generic/Generic1 for data families, and disallowing
      deriving Generic/Generic1 for instantiated types.
      
      Most of this patch is Nicolas Frisby's work.
      156ec95a
  21. 12 Jun, 2012 1 commit
  22. 05 Jun, 2012 1 commit
  23. 26 Apr, 2012 1 commit
  24. 16 Feb, 2012 1 commit
  25. 19 Jan, 2012 1 commit
  26. 03 Jan, 2012 1 commit
    • Simon Peyton Jones's avatar
      Major refactoring of CoAxioms · 98a642cf
      Simon Peyton Jones authored
      This patch should have no user-visible effect.  It implements a
      significant internal refactoring of the way that FC axioms are
      handled.  The ultimate goal is to put us in a position to implement
      "pattern-matching axioms".  But the changes here are only does
      refactoring; there is no change in functionality.
      
      Specifically:
      
       * We now treat data/type family instance declarations very,
         very similarly to types class instance declarations:
      
         - Renamed InstEnv.Instance as InstEnv.ClsInst, for symmetry with
           FamInstEnv.FamInst.  This change does affect the GHC API, but
           for the better I think.
      
         - Previously, each family type/data instance declaration gave rise
           to a *TyCon*; typechecking a type/data instance decl produced
           that TyCon.  Now, each type/data instance gives rise to
           a *FamInst*, by direct analogy with each class instance
           declaration giving rise to a ClsInst.
      
         - Just as each ClsInst contains its evidence, a DFunId, so each FamInst
           contains its evidence, a CoAxiom.  See Note [FamInsts and CoAxioms]
           in FamInstEnv.  The CoAxiom is a System-FC thing, and can relate any
           two types, whereas the FamInst relates directly to the Haskell source
           language construct, and always has a function (F tys) on the LHS.
      
         - Just as a DFunId has its own declaration in an interface file, so now
           do CoAxioms (see IfaceSyn.IfaceAxiom).
      
         These changes give rise to almost all the refactoring.
      
       * We used to have a hack whereby a type family instance produced a dummy
         type synonym, thus
            type instance F Int = Bool -> Bool
         translated to
            axiom FInt :: F Int ~ R:FInt
            type R:FInt = Bool -> Bool
         This was always a hack, and now it's gone.  Instead the type instance
         declaration produces a FamInst, whose axiom has kind
            axiom FInt :: F Int ~ Bool -> Bool
         just as you'd expect.
      
       * Newtypes are done just as before; they generate a CoAxiom. These
         CoAxioms are "implicit" (do not generate an IfaceAxiom declaration),
         unlike the ones coming from family instance declarations.  See
         Note [Implicit axioms] in TyCon
      
      On the whole the code gets significantly nicer.  There were consequential
      tidy-ups in the vectoriser, but I think I got them right.
      98a642cf
  27. 25 Nov, 2011 1 commit
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  31. 04 Oct, 2011 1 commit
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  37. 12 May, 2011 1 commit