1. 25 Nov, 2013 1 commit
    • Simon Peyton Jones's avatar
      Another raft of Template Haskell clean-up · 51deeb0d
      Simon Peyton Jones authored
      The handling of typed and untyped brackets was extremely convoluted,
      partly because of the evolutionary history.  I've tidied it all up.
      
      See Note [How brackets and nested splices are handled] in TcSplice
      for the full story
      
      Main changes:
      
       * Untyped brackets: after the renamer, HsRnBracketOut carries
         PendingRnSplices for splices in untyped brackets.  In the
         typechecker, these pending splices are typechecked quite
         straigtforwardly, with no ps_var nonsense.
      
       * Typed brackets: after the renamer typed brackest still look
         like HsBracket. The type checker does the ps_var thing.
      
       * In TcRnTypes.ThStage, the Brack constructor, we distinguish
         the renaming from typehecking pending-stuff.  Much more
         perspicuous!
      
       * The "typed" flag is in HsSpliceE, not in HsSplice, because
         only expressions can be typed.  Patterns, types, declarations
         cannot.
      
      There is further improvement to be done to make the handling of
      declaration splices more uniform.
      51deeb0d
  2. 04 Oct, 2013 1 commit
  3. 21 Apr, 2013 1 commit
  4. 14 Feb, 2013 1 commit
    • Simon Peyton Jones's avatar
      Add OverloadedLists, allowing list syntax to be overloaded · 3234a4ad
      Simon Peyton Jones authored
      This work was all done by
         Achim Krause <achim.t.krause@gmail.com>
         George Giorgidze <giorgidze@gmail.com>
         Weijers Jeroen <jeroen.weijers@uni-tuebingen.de>
      
      It allows list syntax, such as [a,b], [a..b] and so on, to be
      overloaded so that it works for a variety of types.
      
      The design is described here:
          http://hackage.haskell.org/trac/ghc/wiki/OverloadedLists
      
      Eg. you can use it for maps, so that
              [(1,"foo"), (4,"bar")] :: Map Int String
      
      The main changes
       * The ExplicitList constructor of HsExpr gets witness field
       * Ditto ArithSeq constructor
       * Ditto the ListPat constructor of HsPat
      
      Everything else flows from this.
      3234a4ad
  5. 11 May, 2012 1 commit
    • Simon Peyton Jones's avatar
      Refactor LHsTyVarBndrs to fix Trac #6081 · fc8959ac
      Simon Peyton Jones authored
      This is really a small change, but it touches a lot of files quite
      significantly. The real goal is to put the implicitly-bound kind
      variables of a data/class decl in the right place, namely on the
      LHsTyVarBndrs type, which now looks like
      
        data LHsTyVarBndrs name
          = HsQTvs { hsq_kvs :: [Name]
                   , hsq_tvs :: [LHsTyVarBndr name]
            }
      
      This little change made the type checker neater in a number of
      ways, but it was fiddly to push through the changes.
      fc8959ac
  6. 02 Mar, 2012 1 commit
    • Simon Peyton Jones's avatar
      Hurrah! This major commit adds support for scoped kind variables, · 3bf54e78
      Simon Peyton Jones authored
      which (finally) fills out the functionality of polymorphic kinds.
      It also fixes numerous bugs.
      
      Main changes are:
      
      Renaming stuff
      ~~~~~~~~~~~~~~
      * New type in HsTypes:
           data HsBndrSig sig = HsBSig sig [Name]
        which is used for type signatures in patterns, and kind signatures
        in types.  So when you say
             f (x :: [a]) = x ++ x
        or
             data T (f :: k -> *) (x :: *) = MkT (f x)
        the signatures in both cases are a HsBndrSig.
      
      * The [Name] in HsBndrSig records the variables bound by the
        pattern, that is 'a' in the first example, 'k' in the second,
        and nothing in the third.  The renamer initialises the field.
      
      * As a result I was able to get rid of
           RnHsSyn.extractHsTyNames :: LHsType Name -> NameSet
        and its friends altogether.  Deleted the entire module!
        This led to some knock-on refactoring; in particular the
        type renamer now returns the free variables just like the
        term renamer.
      
      Kind-checking types: mainly TcHsType
      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      A major change is that instead of kind-checking types in two
      passes, we now do one. Under the old scheme, the first pass did
      kind-checking and (hackily) annotated the HsType with the
      inferred kinds; and the second pass desugared the HsType to a
      Type.  But now that we have kind variables inside types, the
      first pass (TcHsType.tc_hs_type) can go straight to Type, and
      zonking will squeeze out any kind unification variables later.
      
      This is much nicer, but it was much more fiddly than I had expected.
      
      The nastiest corner is this: it's very important that tc_hs_type
      uses lazy constructors to build the returned type. See
      Note [Zonking inside the knot] in TcHsType.
      
      Type-checking type and class declarations: mainly TcTyClsDecls
      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      I did tons of refactoring in TcTyClsDecls.  Simpler and nicer now.
      
      Typechecking bindings: mainly TcBinds
      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      I rejigged (yet again) the handling of type signatures in TcBinds.
      It's a bit simpler now.  The main change is that tcTySigs goes
      right through to a TcSigInfo in one step; previously it was split
      into two, part here and part later.
      
      Unsafe coercions
      ~~~~~~~~~~~~~~~~
      Usually equality coercions have exactly the same kind on both
      sides.  But we do allow an *unsafe* coercion between Int# and Bool,
      say, used in
          case error Bool "flah" of { True -> 3#; False -> 0# }
      -->
          (error Bool "flah") |> unsafeCoerce Bool Int#
      
      So what is the instantiation of (~#) here?
         unsafeCoerce Bool Int# :: (~#) ??? Bool Int#
      I'm using OpenKind here for now, but it's un-satisfying that
      the lhs and rhs of the ~ don't have precisely the same kind.
      
      More minor
      ~~~~~~~~~~
      * HsDecl.TySynonym has its free variables attached, which makes
        the cycle computation in TcTyDecls.mkSynEdges easier.
      
      * Fixed a nasty reversed-comparison bug in FamInstEnv:
        @@ -490,7 +490,7 @@ lookup_fam_inst_env' match_fun one_sided ie fam tys
           n_tys = length tys
           extra_tys = drop arity tys
           (match_tys, add_extra_tys)
      -       | arity > n_tys = (take arity tys, \res_tys -> res_tys ++ extra_tys)
      +       | arity < n_tys = (take arity tys, \res_tys -> res_tys ++ extra_tys)
              | otherwise     = (tys,            \res_tys -> res_tys)
      3bf54e78
  7. 16 Feb, 2012 1 commit
  8. 05 Dec, 2011 1 commit
    • Simon Peyton Jones's avatar
      Allow full constraint solving under a for-all (Trac #5595) · 2e6dcdf7
      Simon Peyton Jones authored
      The main idea is that when we unify
          forall a. t1  ~  forall a. t2
      we get constraints from unifying t1~t2 that mention a.
      We are producing a coercion witnessing the equivalence of
      the for-alls, and inside *that* coercion we need bindings
      for the solved constraints arising from t1~t2.
      
      We didn't have way to do this before.  The big change is
      that here's a new type TcEvidence.TcCoercion, which is
      much like Coercion.Coercion except that there's a slot
      for TcEvBinds in it.
      
      This has a wave of follow-on changes. Not deep but broad.
      
      * New module TcEvidence, which now contains the HsWrapper
        TcEvBinds, EvTerm etc types that used to be in HsBinds
      
      * The typechecker works exclusively in terms of TcCoercion.
      
      * The desugarer converts TcCoercion to Coercion
      
      * The main payload is in TcUnify.unifySigmaTy. This is the
        function that had a gross hack before, but is now beautiful.
      
      * LCoercion is gone!  Hooray.
      
      Many many fiddly changes in conssequence.  But it's nice.
      2e6dcdf7
  9. 06 Nov, 2011 2 commits
  10. 04 Nov, 2011 1 commit
  11. 06 Sep, 2011 1 commit
    • batterseapower's avatar
      Implement -XConstraintKind · 9729fe7c
      batterseapower authored
      Basically as documented in http://hackage.haskell.org/trac/ghc/wiki/KindFact,
      this patch adds a new kind Constraint such that:
      
        Show :: * -> Constraint
        (?x::Int) :: Constraint
        (Int ~ a) :: Constraint
      
      And you can write *any* type with kind Constraint to the left of (=>):
      even if that type is a type synonym, type variable, indexed type or so on.
      
      The following (somewhat related) changes are also made:
       1. We now box equality evidence. This is required because we want
          to give (Int ~ a) the *lifted* kind Constraint
       2. For similar reasons, implicit parameters can now only be of
          a lifted kind. (?x::Int#) => ty is now ruled out
       3. Implicit parameter constraints are now allowed in superclasses
          and instance contexts (this just falls out as OK with the new
          constraint solver)
      
      Internally the following major changes were made:
       1. There is now no PredTy in the Type data type. Instead
          GHC checks the kind of a type to figure out if it is a predicate
       2. There is now no AClass TyThing: we represent classes as TyThings
          just as a ATyCon (classes had TyCons anyway)
       3. What used to be (~) is now pretty-printed as (~#). The box
          constructor EqBox :: (a ~# b) -> (a ~ b)
       4. The type LCoercion is used internally in the constraint solver
          and type checker to represent coercions with free variables
          of type (a ~ b) rather than (a ~# b)
      9729fe7c
  12. 27 Jul, 2011 1 commit
  13. 04 May, 2011 1 commit
    • dreixel's avatar
      Remove HsNumTy and TypePati. · fed25228
      dreixel authored
      They belonged to the old generic deriving mechanism, so they can go. Adapted a lot of code as a consequence.
      fed25228
  14. 28 Apr, 2011 1 commit
  15. 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
  16. 16 Nov, 2010 1 commit
    • simonpj@microsoft.com's avatar
      Warn a bit less often about unlifted bindings. · 67157c5c
      simonpj@microsoft.com authored
      Warn when
         (a) a pattern bindings binds unlifted values
         (b) it has no top-level bang
         (c) the RHS has a *lifted* type
      
      Clause (c) is new, argued for by Simon M
      
      Eg     x# = 4# + 4#      -- No warning
             (# a,b #) = blah  -- No warning
             I# x = blah       -- Warning
      67157c5c
  17. 05 Nov, 2010 1 commit
  18. 26 Oct, 2010 1 commit
  19. 13 Sep, 2010 1 commit
  20. 30 Mar, 2010 1 commit
  21. 04 Mar, 2010 1 commit
    • simonpj@microsoft.com's avatar
      Refactor part of the renamer to fix Trac #3901 · f1cc3eb9
      simonpj@microsoft.com authored
      This one was bigger than I anticipated!  The problem was that were
      were gathering the binders from a pattern before renaming -- but with
      record wild-cards we don't know what variables are bound by C {..}
      until after the renamer has filled in the "..".
      
      So this patch does the following
      
      * Change all the collect-X-Binders functions in HsUtils so that
        they expect to only be called *after* renaming.  That means they
        don't need to return [Located id] but just [id].  Which turned out
        to be a very worthwhile simplification all by itself.
      
      * Refactor the renamer, and in ptic RnExpr.rnStmt, so that it
        doesn't need to use collectLStmtsBinders on pre-renamed Stmts.
      
      * This in turn required me to understand how GroupStmt and
        TransformStmts were renamed.  Quite fiddly. I rewrote most of it;
        result is much shorter.
      
      * In doing so I flattened HsExpr.GroupByClause into its parent
        GroupStmt, with trivial knock-on effects in other files.
      
      Blargh.
      f1cc3eb9
  22. 10 Feb, 2010 1 commit
    • simonpj@microsoft.com's avatar
      Several TH/quasiquote changes · 6f8ff0bb
      simonpj@microsoft.com authored
      a) Added quasi-quote forms for
            declarations
            types
         e.g.   f :: [$qq| ... |]
      
      b) Allow Template Haskell pattern quotes (but not splices)
         e.g.  f x = [p| Int -> $x |]
      
      c) Improve pretty-printing for HsPat to remove superfluous
         parens.  (This isn't TH related really, but it affects
         some of the same code.)
      
      
      A consequence of (a) is that when gathering and grouping declarations
      in RnSource.findSplice, we must expand quasiquotes as we do so.
      Otherwise it's all fairly straightforward.  I did a little bit of
      refactoring in TcSplice.
      
      User-manual changes still to come.
      6f8ff0bb
  23. 29 Oct, 2009 1 commit
  24. 21 Aug, 2009 1 commit
  25. 10 Aug, 2009 1 commit
  26. 09 Aug, 2009 1 commit
  27. 07 Aug, 2009 1 commit
  28. 23 Jul, 2009 1 commit
  29. 13 Jul, 2008 1 commit
  30. 12 Apr, 2008 1 commit
  31. 22 Apr, 2008 1 commit
  32. 28 Jan, 2008 1 commit
  33. 27 Jan, 2008 1 commit
  34. 18 Jan, 2008 1 commit
    • simonpj@microsoft.com's avatar
      Add quasi-quotation, courtesy of Geoffrey Mainland · f3399c44
      simonpj@microsoft.com authored
      This patch adds quasi-quotation, as described in
        "Nice to be Quoted: Quasiquoting for Haskell"
      	(Geoffrey Mainland, Haskell Workshop 2007)
      Implemented by Geoffrey and polished by Simon.
      
      Overview
      ~~~~~~~~
      The syntax for quasiquotation is very similar to the existing
      Template haskell syntax:
      	[$q| stuff |]
      where 'q' is the "quoter".  This syntax differs from the paper, by using
      a '$' rather than ':', to avoid clashing with parallel array comprehensions.
       
      The "quoter" is a value of type Language.Haskell.TH.Quote.QuasiQuoter, which
      contains two functions for quoting expressions and patterns, respectively.
       
           quote = Language.Haskell.TH.Quote.QuasiQuoter quoteExp quotePat
       
           quoteExp :: String -> Language.Haskell.TH.ExpQ
           quotePat :: String -> Language.Haskell.TH.PatQ
      
      TEXT is passed unmodified to the quoter. The context of the
      quasiquotation statement determines which of the two quoters is
      called: if the quasiquotation occurs in an expression context,
      quoteExp is called, and if it occurs in a pattern context, quotePat
      is called.
      
      The result of running the quoter on its arguments is spliced into
      the program using Template Haskell's existing mechanisms for
      splicing in code. Note that although Template Haskell does not
      support pattern brackets, with this patch binding occurrences of
      variables in patterns are supported. Quoters must also obey the same
      stage restrictions as Template Haskell; in particular, in this
      example quote may not be defined in the module where it is used as a
      quasiquoter, but must be imported from another module.
      
      Points to notice
      ~~~~~~~~~~~~~~~~
      * The whole thing is enabled with the flag -XQuasiQuotes
      
      * There is an accompanying patch to the template-haskell library. This
        involves one interface change:
      	currentModule :: Q String
        is replaced by
      	location :: Q Loc
        where Loc is a data type defined in TH.Syntax thus:
            data Loc
              = Loc { loc_filename :: String
      	      , loc_package  :: String
      	      , loc_module   :: String
      	      , loc_start    :: CharPos
      	      , loc_end      :: CharPos }
      
            type CharPos = (Int, Int)	-- Line and character position
       
        So you get a lot more info from 'location' than from 'currentModule'.
        The location you get is the location of the splice.
        
        This works in Template Haskell too of course, and lets a TH program
        generate much better error messages.
      
      * There's also a new module in the template-haskell package called 
        Language.Haskell.TH.Quote, which contains support code for the
        quasi-quoting feature.
      
      * Quasi-quote splices are run *in the renamer* because they can build 
        *patterns* and hence the renamer needs to see the output of running the
        splice.  This involved a bit of rejigging in the renamer, especially
        concerning the reporting of duplicate or shadowed names.
      
        (In fact I found and removed a few calls to checkDupNames in RnSource 
        that are redundant, becuase top-level duplicate decls are handled in
        RnNames.)
      
      
      f3399c44
  35. 07 Jan, 2008 1 commit
    • simonpj@microsoft.com's avatar
      Make the treatment of equalities more uniform · 3787d987
      simonpj@microsoft.com authored
      This patch (which is part of the fix for Trac #2018) makes coercion variables
      be handled more uniformly.  Generally, they are treated like dictionaries
      in the type checker, not like type variables, but in a couple of places we
      were treating them like type variables.  Also when zonking we should use
      zonkDictBndr not zonkIdBndr.
      3787d987
  36. 10 Oct, 2007 1 commit
    • Dan Licata's avatar
      View patterns, record wildcards, and record puns · 6a05ec5e
      Dan Licata authored
      This patch implements three new features:
      * view patterns (syntax: expression -> pat in a pattern)
      * working versions of record wildcards and record puns
      See the manual for detailed descriptions.
      
      Other minor observable changes:
      * There is a check prohibiting local fixity declarations
        when the variable being fixed is not defined in the same let
      * The warn-unused-binds option now reports warnings for do and mdo stmts
      
      Implementation notes: 
      
      * The pattern renamer is now in its own module, RnPat, and the
      implementation is now in a CPS style so that the correct context is
      delivered to pattern expressions.
      
      * These features required a fairly major upheaval to the renamer.
      Whereas the old version used to collect up all the bindings from a let
      (or top-level, or recursive do statement, ...) and put them into scope
      before renaming anything, the new version does the collection as it
      renames.  This allows us to do the right thing with record wildcard
      patterns (which need to be expanded to see what names should be
      collected), and it allows us to implement the desired semantics for view
      patterns in lets.  This change had a bunch of domino effects brought on
      by fiddling with the top-level renaming.
      
      * Prior to this patch, there was a tricky bug in mkRecordSelId in HEAD,
      which did not maintain the invariant necessary for loadDecl.  See note
      [Tricky iface loop] for details.
      6a05ec5e
  37. 28 Sep, 2007 1 commit
  38. 04 Sep, 2007 1 commit
  39. 03 Sep, 2007 1 commit