1. 06 Dec, 2006 1 commit
  2. 10 Nov, 2006 1 commit
  3. 11 Oct, 2006 1 commit
  4. 05 Oct, 2006 1 commit
  5. 21 Sep, 2006 1 commit
  6. 20 Sep, 2006 1 commit
  7. 18 Sep, 2006 1 commit
  8. 17 Sep, 2006 1 commit
  9. 29 Sep, 2006 1 commit
  10. 20 Sep, 2006 2 commits
    • chak@cse.unsw.edu.au.'s avatar
      Kind sig for toplevel family decls is optional · 7ab880e6
      chak@cse.unsw.edu.au. authored
      Mon Sep 18 19:13:47 EDT 2006  Manuel M T Chakravarty <chak@cse.unsw.edu.au>
        * Kind sig for toplevel family decls is optional
        Sat Aug 26 19:03:50 EDT 2006  Manuel M T Chakravarty <chak@cse.unsw.edu.au>
          * Kind sig for toplevel family decls is optional
          - Kind sigs are still compulsory for AT family decls.  Changing this is more 
            tricky, as AT decls don't have the family keyword and hence look like empty 
            data decls.  That impacts reduce/reduce conflicts and/or the criteria for 
            checking whether a TyData variant is a family signature.
          - Also removed iso from the syntax (it's still in the lexer in case we want to
            resurrect it). 
    • chak@cse.unsw.edu.au.'s avatar
      Extend Class.Class to include the TyCons of ATs · bb106f28
      chak@cse.unsw.edu.au. authored
      Mon Sep 18 18:58:51 EDT 2006  Manuel M T Chakravarty <chak@cse.unsw.edu.au>
        * Extend Class.Class to include the TyCons of ATs
        Wed Aug 16 16:15:31 EDT 2006  Manuel M T Chakravarty <chak@cse.unsw.edu.au>
          * Extend Class.Class to include the TyCons of ATs
  11. 18 Sep, 2006 3 commits
  12. 15 Sep, 2006 5 commits
  13. 02 Aug, 2006 1 commit
  14. 18 Sep, 2006 1 commit
  15. 12 Sep, 2006 1 commit
  16. 21 Aug, 2006 2 commits
  17. 09 Aug, 2006 1 commit
  18. 25 Jul, 2006 1 commit
    • Simon Marlow's avatar
      Generalise Package Support · 61d2625a
      Simon Marlow authored
      This patch pushes through one fundamental change: a module is now
      identified by the pair of its package and module name, whereas
      previously it was identified by its module name alone.  This means
      that now a program can contain multiple modules with the same name, as
      long as they belong to different packages.
      This is a language change - the Haskell report says nothing about
      packages, but it is now necessary to understand packages in order to
      understand GHC's module system.  For example, a type T from module M
      in package P is different from a type T from module M in package Q.
      Previously this wasn't an issue because there could only be a single
      module M in the program.
      The "module restriction" on combining packages has therefore been
      lifted, and a program can contain multiple versions of the same
      Note that none of the proposed syntax changes have yet been
      implemented, but the architecture is geared towards supporting import
      declarations qualified by package name, and that is probably the next
      It is now necessary to specify the package name when compiling a
      package, using the -package-name flag (which has been un-deprecated).
      Fortunately Cabal still uses -package-name.
      Certain packages are "wired in".  Currently the wired-in packages are:
      base, haskell98, template-haskell and rts, and are always referred to
      by these versionless names.  Other packages are referred to with full
      package IDs (eg. "network-1.0").  This is because the compiler needs
      to refer to entities in the wired-in packages, and we didn't want to
      bake the version of these packages into the comiler.  It's conceivable
      that someone might want to upgrade the base package independently of
      Internal changes:
        - There are two module-related types:
              ModuleName      just a FastString, the name of a module
              Module          a pair of a PackageId and ModuleName
          A mapping from ModuleName can be a UniqFM, but a mapping from Module
          must be a FiniteMap (we provide it as ModuleEnv).
        - The "HomeModules" type that was passed around the compiler is now
          gone, replaced in most cases by the current package name which is
          contained in DynFlags.  We can tell whether a Module comes from the
          current package by comparing its package name against the current
        - While I was here, I changed PrintUnqual to be a little more useful:
          it now returns the ModuleName that the identifier should be qualified
          with according to the current scope, rather than its original
          module.  Also, PrintUnqual tells whether to qualify module names with
          package names (currently unused).
      Docs to follow.
  19. 23 Jun, 2006 1 commit
  20. 19 May, 2006 1 commit
  21. 14 Apr, 2006 1 commit
    • simonpj@microsoft.com's avatar
      Allow $x, as well as $(x), at top level in TH · 6b2cf62b
      simonpj@microsoft.com authored
      Bulat pointed out that in Template Haskell
      is allowed instead of 
      in expressions, but not at the top level of modules.
      This commit fixes the omission.  Now you can say
      	f x = x
      	data T = T
      and the $h will run Template Haskell just as you'd expect.
  22. 07 Apr, 2006 1 commit
    • Simon Marlow's avatar
      Reorganisation of the source tree · 0065d5ab
      Simon Marlow authored
      Most of the other users of the fptools build system have migrated to
      Cabal, and with the move to darcs we can now flatten the source tree
      without losing history, so here goes.
      The main change is that the ghc/ subdir is gone, and most of what it
      contained is now at the top level.  The build system now makes no
      pretense at being multi-project, it is just the GHC build system.
      No doubt this will break many things, and there will be a period of
      instability while we fix the dependencies.  A straightforward build
      should work, but I haven't yet fixed binary/source distributions.
      Changes to the Building Guide will follow, too.
  23. 05 Mar, 2006 1 commit
  24. 01 Mar, 2006 1 commit
  25. 03 Feb, 2006 1 commit
  26. 25 Jan, 2006 1 commit
    • simonpj@microsoft.com's avatar
      Simon's big boxy-type commit · ac10f840
      simonpj@microsoft.com authored
      This very large commit adds impredicativity to GHC, plus
      numerous other small things.
      *** WARNING: I have compiled all the libraries, and
      ***	     a stage-2 compiler, and everything seems
      ***	     fine.  But don't grab this patch if you 
      ***	     can't tolerate a hiccup if something is
      ***	     broken.
      The big picture is this:
      a) GHC handles impredicative polymorphism, as described in the
         "Boxy types: type inference for higher-rank types and
         impredicativity" paper
      b) GHC handles GADTs in the new simplified (and very sligtly less
         epxrssive) way described in the
         "Simple unification-based type inference for GADTs" paper
      But there are lots of smaller changes, and since it was pre-Darcs
      they are not individually recorded.
      Some things to watch out for:
      c)   The story on lexically-scoped type variables has changed, as per
           my email.  I append the story below for completeness, but I 
           am still not happy with it, and it may change again.  In particular,
           the new story does not allow a pattern-bound scoped type variable
           to be wobbly, so (\(x::[a]) -> ...) is usually rejected.  This is
           more restrictive than before, and we might loosen up again.
      d)   A consequence of adding impredicativity is that GHC is a bit less
           gung ho about converting automatically between
        	(ty1 -> forall a. ty2)    and    (forall a. ty1 -> ty2)
           In particular, you may need to eta-expand some functions to make
           typechecking work again.
           Furthermore, functions are now invariant in their argument types,
           rather than being contravariant.  Again, the main consequence is
           that you may occasionally need to eta-expand function arguments when
           using higher-rank polymorphism.
      Please test, and let me know of any hiccups
      Scoped type variables in GHC
      	January 2006
      0) Terminology.
         A *pattern binding* is of the form
      	pat = rhs
         A *function binding* is of the form
      	f pat1 .. patn = rhs
         A binding of the formm
      	var = rhs
         is treated as a (degenerate) *function binding*.
         A *declaration type signature* is a separate type signature for a
         let-bound or where-bound variable:
      	f :: Int -> Int
         A *pattern type signature* is a signature in a pattern: 
      	\(x::a) -> x
      	f (x::a) = x
         A *result type signature* is a signature on the result of a
         function definition:
      	f :: forall a. [a] -> a
      	head (x:xs) :: a = x
         The form
      	x :: a = rhs
         is treated as a (degnerate) function binding with a result
         type signature, not as a pattern binding.
      1) The main invariants:
           A) A lexically-scoped type variable always names a (rigid)
       	type variable (not an arbitrary type).  THIS IS A CHANGE.
              Previously, a scoped type variable named an arbitrary *type*.
           B) A type signature always describes a rigid type (since
      	its free (scoped) type variables name rigid type variables).
      	This is also a change, a consequence of (A).
           C) Distinct lexically-scoped type variables name distinct
      	rigid type variables.  This choice is open; 
      2) Scoping
      2(a) If a declaration type signature has an explicit forall, those type
         variables are brought into scope in the right hand side of the 
         corresponding binding (plus, for function bindings, the patterns on
         the LHS).  
      	f :: forall a. a -> [a]
      	f (x::a) = [x :: a, x]
         Both occurences of 'a' in the second line are bound by 
         the 'forall a' in the first line
         A declaration type signature *without* an explicit top-level forall
         is implicitly quantified over all the type variables that are
         mentioned in the type but not already in scope.  GHC's current
         rule is that this implicit quantification does *not* bring into scope
         any new scoped type variables.
      	f :: a -> a
      	f x = ...('a' is not in scope here)...
         This gives compatibility with Haskell 98
      2(b) A pattern type signature implicitly brings into scope any type
         variables mentioned in the type that are not already into scope.
         These are called *pattern-bound type variables*.
      	g :: a -> a -> [a]
      	g (x::a) (y::a) = [y :: a, x]
         The pattern type signature (x::a) brings 'a' into scope.
         The 'a' in the pattern (y::a) is bound, as is the occurrence on 
         the RHS.  
         A pattern type siganture is the only way you can bring existentials 
         into scope.
      	data T where
      	  MkT :: forall a. a -> (a->Int) -> T
      	f x = case x of
      		MkT (x::a) f -> f (x::a)
      2a) QUESTION
      	class C a where
      	  op :: forall b. b->a->a
      	instance C (T p q) where
      	  op = <rhs>
          Clearly p,q are in scope in <rhs>, but is 'b'?  Not at the moment.
          Nor can you add a type signature for op in the instance decl.
          You'd have to say this:
      	instance C (T p q) where
      	  op = let op' :: forall b. ...
      	           op' = <rhs>
      	       in op'
      3) A pattern-bound type variable is allowed only if the pattern's
         expected type is rigid.  Otherwise we don't know exactly *which*
         skolem the scoped type variable should be bound to, and that means
         we can't do GADT refinement.  This is invariant (A), and it is a 
         big change from the current situation.
      	f (x::a) = x	-- NO; pattern type is wobbly
      	g1 :: b -> b
      	g1 (x::b) = x	-- YES, because the pattern type is rigid
      	g2 :: b -> b
      	g2 (x::c) = x	-- YES, same reason
      	h :: forall b. b -> b
      	h (x::b) = x	-- YES, but the inner b is bound
      	k :: forall b. b -> b
      	k (x::c) = x	-- NO, it can't be both b and c
      3a) You cannot give different names for the same type variable in the same scope
          (Invariant (C)):
      	f1 :: p -> p -> p		-- NO; because 'a' and 'b' would be
      	f1 (x::a) (y::b) = (x::a)	--     bound to the same type variable
      	f2 :: p -> p -> p		-- OK; 'a' is bound to the type variable
      	f2 (x::a) (y::a) = (x::a)	--     over which f2 is quantified
      					-- NB: 'p' is not lexically scoped
      	f3 :: forall p. p -> p -> p	-- NO: 'p' is now scoped, and is bound to
      	f3 (x::a) (y::a) = (x::a)	--     to the same type varialble as 'a'
      	f4 :: forall p. p -> p -> p	-- OK: 'p' is now scoped, and its occurences
      	f4 (x::p) (y::p) = (x::p)	--     in the patterns are bound by the forall
      3b) You can give a different name to the same type variable in different
          disjoint scopes, just as you can (if you want) give diferent names to 
          the same value parameter
      	g :: a -> Bool -> Maybe a
      	g (x::p) True  = Just x  :: Maybe p
      	g (y::q) False = Nothing :: Maybe q
      3c) Scoped type variables respect alpha renaming. For example, 
          function f2 from (3a) above could also be written:
      	f2' :: p -> p -> p
      	f2' (x::b) (y::b) = x::b
         where the scoped type variable is called 'b' instead of 'a'.
      4) Result type signatures obey the same rules as pattern types signatures.
         In particular, they can bind a type variable only if the result type is rigid
      	f x :: a = x	-- NO
      	g :: b -> b
      	g x :: b = x	-- YES; binds b in rhs
      5) A *pattern type signature* in a *pattern binding* cannot bind a 
         scoped type variable
      	(x::a, y) = ...		-- Legal only if 'a' is already in scope
         Reason: in type checking, the "expected type" of the LHS pattern is
         always wobbly, so we can't bind a rigid type variable.  (The exception
         would be for an existential type variable, but existentials are not
         allowed in pattern bindings either.)
         Even this is illegal
      	f :: forall a. a -> a
      	f x = let ((y::b)::a, z) = ... 
         Here it looks as if 'b' might get a rigid binding; but you can't bind
         it to the same skolem as a.
      6) Explicitly-forall'd type variables in the *declaration type signature(s)*
         for a *pattern binding* do not scope AT ALL.
      	x :: forall a. a->a	  -- NO; the forall a does 
      	Just (x::a->a) = Just id  --     not scope at all
      	y :: forall a. a->a
      	Just y = Just (id :: a->a)  -- NO; same reason
         THIS IS A CHANGE, but one I bet that very few people will notice.
         Here's why:
      	strange :: forall b. (b->b,b->b)
      	strange = (id,id)
      	x1 :: forall a. a->a
      	y1 :: forall b. b->b
      	(x1,y1) = strange
          This is legal Haskell 98 (modulo the forall). If both 'a' and 'b'
          both scoped over the RHS, they'd get unified and so cannot stand
          for distinct type variables. One could *imagine* allowing this:
      	x2 :: forall a. a->a
      	y2 :: forall a. a->a
      	(x2,y2) = strange
          using the very same type variable 'a' in both signatures, so that
          a single 'a' scopes over the RHS.  That seems defensible, but odd,
          because though there are two type signatures, they introduce just
          *one* scoped type variable, a.
      7) Possible extension.  We might consider allowing
      	\(x :: [ _ ]) -> <expr>
          where "_" is a wild card, to mean "x has type list of something", without
          naming the something.
  27. 06 Jan, 2006 1 commit
    • simonmar's avatar
      [project @ 2006-01-06 16:30:17 by simonmar] · 9d7da331
      simonmar authored
      Add support for UTF-8 source files
      GHC finally has support for full Unicode in source files.  Source
      files are now assumed to be UTF-8 encoded, and the full range of
      Unicode characters can be used, with classifications recognised using
      the implementation from Data.Char.  This incedentally means that only
      the stage2 compiler will recognise Unicode in source files, because I
      was too lazy to port the unicode classifier code into libcompat.
      Additionally, the following synonyms for keywords are now recognised:
        forall symbol 	(U+2200)	forall
        right arrow   	(U+2192)	->
        left arrow   		(U+2190)	<-
        horizontal ellipsis 	(U+22EF)	..
      there are probably more things we could add here.
      This will break some source files if Latin-1 characters are being used.
      In most cases this should result in a UTF-8 decoding error.  Later on
      if we want to support more encodings (perhaps with a pragma to specify
      the encoding), I plan to do it by recoding into UTF-8 before parsing.
      Internally, there were some pretty big changes:
        - FastStrings are now stored in UTF-8
        - Z-encoding has been moved right to the back end.  Previously we
          used to Z-encode every identifier on the way in for simplicity,
          and only decode when we needed to show something to the user.
          Instead, we now keep every string in its UTF-8 encoding, and
          Z-encode right before printing it out.  To avoid Z-encoding the
          same string multiple times, the Z-encoding is cached inside the
          FastString the first time it is requested.
          This speeds up the compiler - I've measured some definite
          improvement in parsing at least, and I expect compilations overall
          to be faster too.  It also cleans up a lot of cruft from the
          OccName interface.  Z-encoding is nicely hidden inside the
          Outputable instance for Names & OccNames now.
        - StringBuffers are UTF-8 too, and are now represented as
        - I've put together some test cases, not by any means exhaustive,
          but there are some interesting UTF-8 decoding error cases that
          aren't obvious.  Also, take a look at unicode001.hs for a demo.
  28. 16 Nov, 2005 1 commit
    • simonpj's avatar
      [project @ 2005-11-16 17:45:38 by simonpj] · 491c85e7
      simonpj authored
      Better error reporting for newtypes with too many constructors,
      or too many fields.  Instead of yielding a parse error, we
      parse it like a data type declaration, and give a comprehensible
      error message later.
      A suggestion from Jan-Willem.
  29. 12 Nov, 2005 1 commit
    • simonpj's avatar
      [project @ 2005-11-12 21:41:12 by simonpj] · 87998beb
      simonpj authored
      Better TH -> HsSyn conversion
      	Merge to stable (attempt)
      This commit monad-ises the TH syntax -> HS syntax conversion.
      This means that error messages can be reported in a more civilised
      way.  It also ensures that the entire structure is converted eagerly.
      That means that any exceptions buried inside it are triggered 
      during conversion, and caught by the exception handler in TcSplice.
      Before, they could be triggered later, and looked like comiler
  30. 31 Oct, 2005 1 commit
  31. 27 Oct, 2005 1 commit
    • simonpj's avatar
      [project @ 2005-10-27 14:35:20 by simonpj] · 958924a2
      simonpj authored
      Add a new pragma: SPECIALISE INLINE
      This amounts to adding an INLINE pragma to the specialised version
      of the function.  You can add phase stuff too (SPECIALISE INLINE [2]),
      and NOINLINE instead of INLINE.
      The reason for doing this is to support inlining of type-directed
      recursive functions.  The main example is this:
        -- non-uniform array type
        data Arr e where
          ArrInt  :: !Int -> ByteArray#       -> Arr Int
          ArrPair :: !Int -> Arr e1 -> Arr e2 -> Arr (e1, e2)
        (!:) :: Arr e -> Int -> e
        {-# SPECIALISE INLINE (!:) :: Arr Int -> Int -> Int #-}
        {-# SPECIALISE INLINE (!:) :: Arr (a, b) -> Int -> (a, b) #-}
        ArrInt  _ ba    !: (I# i) = I# (indexIntArray# ba i)
        ArrPair _ a1 a2 !: i      = (a1 !: i, a2 !: i)
      If we use (!:) at a particular array type, we want to inline (:!),
      which is recursive, until all the type specialisation is done.
      On the way I did a bit of renaming and tidying of the way that
      pragmas are carried, so quite a lot of files are touched in a
      fairly trivial way.
  32. 14 Oct, 2005 1 commit
    • simonpj's avatar
      [project @ 2005-10-14 11:22:41 by simonpj] · 36436bc6
      simonpj authored
      Add record syntax for GADTs
      Atrijus Tang wanted to add record syntax for GADTs and existential
      types, so he and I worked on it a bit at ICFP.  This commit is the
      result.  Now you can say
       data T a where
        T1 { x :: a }           	 :: T [a]
        T2 { x :: a, y :: Int } 	 :: T [a]
        forall b. Show b =>
       	T3 { naughty :: b, ok :: Int } :: T Int
        T4 :: Eq a => a -> b -> T (a,b)
      Here the constructors are declared using record syntax.
      Still to come after this commit:
        - User manual documentation
        - More regression tests
        - Some missing cases in the parser (e.g. T3 won't parse)
      Autrijus is going to do these.
      Here's a quick summary of the rules.  (Atrijus is going to write
      proper documentation shortly.)
      Defnition: a 'vanilla' constructor has a type of the form
      	forall a1..an. t1 -> ... -> tm -> T a1 ... an
      No existentials, no context, nothing.  A constructor declared with
      Haskell-98 syntax is vanilla by construction.  A constructor declared
      with GADT-style syntax is vanilla iff its type looks like the above.
      (In the latter case, the order of the type variables does not matter.)
      * You can mix record syntax and non-record syntax in a single decl
      * All constructors that share a common field 'x' must have the
        same result type (T [a] in the example).
      * You can use field names without restriction in record construction
        and record pattern matching.
      * Record *update* only works for data types that only have 'vanilla'
      * Consider the field 'naughty', which uses a type variable that does
        not appear in the result type ('b' in the example).  You can use the
        field 'naughty' in pattern matching and construction, but NO
        SELECTOR function is generated for 'naughty'.  [An attempt to use
        'naughty' as a selector function will elicit a helpful error
      * Data types declared in GADT syntax cannot have a context. So this
      is illegal:
      	data (Monad m) => T a where
      * Constructors in GADT syntax can have a context (t.g. T3, T4 above)
        and that context is stored in the constructor and made available
        when the constructor is pattern-matched on.  WARNING: not competely
        implemented yet, but that's the plan.
      Implementation notes
      - Data constructors (even vanilla ones) no longer share the type
        variables of their parent type constructor.
      - HsDecls.ConDecl has changed quite a bit
      - TyCons don't record the field labels and type any more (doesn't
        make sense for existential fields)
      - GlobalIdDetails records which selectors are 'naughty', and hence
        don't have real code.