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  1. 25 Apr, 2007 1 commit
    • chak@cse.unsw.edu.au.'s avatar
      Generating synonym instance representation tycons · 13cd965d
      chak@cse.unsw.edu.au. authored
      - Type synonym instances are turned into representation synonym tycons
      - They are entered into the pool of family instances (FamInst environments)
        in the same way as data/newtype instances
      - Still missing is writing the parent tycon information into ifaces and 
        various well-formedness checks.
      13cd965d
  2. 10 Dec, 2006 1 commit
    • mnislaih's avatar
      Retrieving the datacon of an arbitrary closure · ab5b8aa3
      mnislaih authored
      This patch extends the RTS linker and the dynamic linker so that it is possible to find out the datacon of a closure in heap at runtime:
      - The RTS linker now carries a hashtable 'Address->Symbol' for data constructors
      - The Persistent Linker State in the dynamic linker is extended in a similar way.
      
      Finally, these two sources of information are consulted by:
      
      > Linker.recoverDataCon :: a -> TcM Name
      ab5b8aa3
  3. 10 Nov, 2006 1 commit
  4. 18 Oct, 2006 1 commit
    • simonpj@microsoft.com's avatar
      Add the primitive type Any, and use it for Dynamics · c128930d
      simonpj@microsoft.com authored
      GHC's code generator can only enter a closure if it's guaranteed
      not to be a function.  In the Dynamic module, we were using the 
      type (forall a.a) as the type to which the dynamic type was unsafely
      cast:
      	type Obj = forall a.a
      
      Gut alas this polytype was sometimes instantiated to (), something 
      like this (it only bit when profiling was enabled)
      	let y::() = dyn ()
      	in (y `cast` ..) p q
      As a result, an ASSERT in ClosureInfo fired (hooray).
      
      I've tided this up by making a new, primitive, lifted type Any, and
      arranging that Dynamic uses Any, thus:
      	type Obj = ANy
      
      While I was at it, I also arranged that when the type checker instantiates 
      un-constrained type variables, it now instantiates them to Any, not ()
      	e.g.  length Any []
      
      [There remains a Horrible Hack when we want Any-like things at arbitrary 
      kinds.  This essentially never happens, but see comments with 
      TysPrim.mkAnyPrimTyCon.]
      
      Anyway, this fixes Trac #905
      c128930d
  5. 11 Oct, 2006 1 commit
    • Simon Marlow's avatar
      Interface file optimisation and removal of nameParent · b00b5bc0
      Simon Marlow authored
      This large commit combines several interrelated changes:
      
        - IfaceSyn now contains actual Names rather than the special
          IfaceExtName type.  The binary interface file contains
          a symbol table of Names, where each entry is a (package,
          ModuleName, OccName) triple.  Names in the IfaceSyn point
          to entries in the symbol table.
      
          This reduces the size of interface files, which should
          hopefully improve performance (not measured yet).
      
          The toIfaceXXX functions now do not need to pass around
          a function from Name -> IfaceExtName, which makes that
          code simpler.
      
        - Names now do not point directly to their parents, and the
          nameParent operation has gone away.  It turned out to be hard to
          keep this information consistent in practice, and the parent info
          was only valid in some Names.  Instead we made the following
          changes:
      
          * ImportAvails contains a new field 
                imp_parent :: NameEnv AvailInfo
            which gives the family info for any Name in scope, and
            is used by the renamer when renaming export lists, amongst
            other things.  This info is thrown away after renaming.
      
          * The mi_ver_fn field of ModIface now maps to
            (OccName,Version) instead of just Version, where the
            OccName is the parent name.  This mapping is used when
            constructing the usage info for dependent modules.
            There may be entries in mi_ver_fn for things that are not in
            scope, whereas imp_parent only deals with in-scope things.
      
          * The md_exports field of ModDetails now contains
            [AvailInfo] rather than NameSet.  This gives us
            family info for the exported names of a module.
      
      Also:
      
         - ifaceDeclSubBinders moved to IfaceSyn (seems like the
           right place for it).
      
         - heavily refactored renaming of import/export lists.
      
         - Unfortunately external core is now broken, as it relied on
           IfaceSyn.  It requires some attention.
      b00b5bc0
  6. 20 Sep, 2006 2 commits
    • chak@cse.unsw.edu.au.'s avatar
      Introduce coercions for data instance decls · 909d2dd8
      chak@cse.unsw.edu.au. authored
      Mon Sep 18 19:07:30 EDT 2006  Manuel M T Chakravarty <chak@cse.unsw.edu.au>
        * Introduce coercions for data instance decls
        Tue Aug 22 20:33:46 EDT 2006  Manuel M T Chakravarty <chak@cse.unsw.edu.au>
          * Introduce coercions for data instance decls
          - data instance declarations implicitly generate a coercion moving between the
            representation type and family instance type.
          - The coercion is *implicitly* generated when type checking both source and 
            ifaces.  Ie, we don't safe it in ifaces - this is really exactly as newtype 
            coercions are handled.
          - The previous addition of the instance types to DataCons has been moved to 
            the representation TyCon.  This is more efficient as it is shared between all
            constructors of one representation tycon and it also gathers everything about
            data instances (family tycon, instance types, and coercion) in one place: the
            algTcParent field of TyCon.
          - The coercion is already used in the datacon wrappers, but not yet during type
            checking pattern matching of indexed data types.
          - The code has only been lightly tested, but doesn't seem to break features not
            related to indexed types.  For indexed data types only the pattern matching
            tc code (in TcPat.tcConPat) and some well-formedness checks are still 
            missing.  And there will surely be some bugs to fix.  (newtypes still require
            some more work.)
          
          	   ** WARNING: Interface file format changed! **
          	   **          Recompile from scratch!        **
      909d2dd8
    • chak@cse.unsw.edu.au.'s avatar
      Extend TyCons and DataCons to represent data instance decls · 80c89b80
      chak@cse.unsw.edu.au. authored
      Mon Sep 18 19:05:18 EDT 2006  Manuel M T Chakravarty <chak@cse.unsw.edu.au>
        * Extend TyCons and DataCons to represent data instance decls
        Fri Aug 18 19:11:37 EDT 2006  Manuel M T Chakravarty <chak@cse.unsw.edu.au>
          * Extend TyCons and DataCons to represent data instance decls
          - This is a faily involved patch, but it is not entirely complete:
            + The data con wrapper code for instance data cons needs to apply the
              coercions (which we still have to generate).
            + There are still bugs, but it doesn't seem to affect the compilation of
              code that doesn't use type families.
          
          ** WARNING: Yet another change of the iface format.  **
          **          Recompile everything.                    **
      80c89b80
  7. 18 Sep, 2006 1 commit
    • chak@cse.unsw.edu.au.'s avatar
      Remove argument variance info of tycons · 3e0b6b25
      chak@cse.unsw.edu.au. authored
      Fri Aug 11 13:53:24 EDT 2006  Manuel M T Chakravarty <chak@cse.unsw.edu.au>
        * Remove argument variance info of tycons
        - Following SPJ's suggestion, this patch removes the variance information from
          type constructors.  This information was computed, but never used.
        
        ** WARNING: This patch changes the format of interface files **
        **          You will need to rebuild from scratch.           **
      3e0b6b25
  8. 04 Aug, 2006 1 commit
  9. 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
      package.
      
      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
      step.
      
      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
      GHC.
      
      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
          package.
      
        - 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.
      61d2625a
  10. 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.
      0065d5ab
  11. 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
          ForeignPtrs.
      
        - 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.
      9d7da331
  12. 19 May, 2005 1 commit
    • simonpj's avatar
      [project @ 2005-05-19 11:15:40 by simonpj] · 4a587049
      simonpj authored
      Tune up the reporting of unused imports
      
      		Merge to STABLE
      	(I think the earlier change made it across)
      	(PS: the commit also does some trimming of
      	redundant imports.  If they don't merge, just
      	discard them.)
      
      My earlier fixes to the reporting of unused imports still missed
      some obscure cases, some of which are now fixed by this commit.
      I had to make the import-provenance data type yet richer, but in
      fact it has more sharing now, so it may be cheaper on space.
      
      There's still one infelicity. Consider
      		import M( x )
      		imoprt N( x )
      where the same underlying 'x' is involved in both cases.  Currently we
      don't report a redundant import, because dropping either import would
      change the qualified names in scope (M.x, N.x). But if the qualified
      names aren't used, the import is indeed redundant. Sadly we don't know
      that, because we only know what Names are used.  Left for the future!
      There's a comment in RnNames.warnDuplicateImports
      
      This commit also trims quite a few redundant imports disovered
      by the new setup.
      4a587049
  13. 28 Apr, 2005 1 commit
    • simonpj's avatar
      [project @ 2005-04-28 10:09:41 by simonpj] · dd313897
      simonpj authored
      This big commit does several things at once (aeroplane hacking)
      which change the format of interface files.  
      
      	So you'll need to recompile your libraries!
      
      1. The "stupid theta" of a newtype declaration
      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      Retain the "stupid theta" in a newtype declaration.
      For some reason this was being discarded, and putting it
      back in meant changing TyCon and IfaceSyn slightly.
         
      
      2. Overlap flags travel with the instance
      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      Arrange that the ability to support overlap and incoherence
      is a property of the *instance declaration* rather than the
      module that imports the instance decl.  This allows a library
      writer to define overlapping instance decls without the
      library client having to know.  
      
      The implementation is that in an Instance we store the
      overlap flag, and preseve that across interface files
      
      
      3. Nuke the "instnce pool" and "rule pool"
      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      A major tidy-up and simplification of the way that instances
      and rules are sucked in from interface files.  Up till now
      an instance decl has been held in a "pool" until its "gates" 
      (a set of Names) are in play, when the instance is typechecked
      and added to the InstEnv in the ExternalPackageState.  
      This is complicated and error-prone; it's easy to suck in 
      too few (and miss an instance) or too many (and thereby be
      forced to suck in its type constructors, etc).
      
      Now, as we load an instance from an interface files, we 
      put it straight in the InstEnv... but the Instance we put in
      the InstEnv has some Names (the "rough-match" names) that 
      can be used on lookup to say "this Instance can't match".
      The detailed dfun is only read lazily, and the rough-match
      thing meansn it is'nt poked on until it has a chance of
      being needed.
      
      This simply continues the successful idea for Ids, whereby
      they are loaded straightaway into the TypeEnv, but their
      TyThing is a lazy thunk, not poked on until the thing is looked
      up.
      
      Just the same idea applies to Rules.
      
      On the way, I made CoreRule and Instance into full-blown records
      with lots of info, with the same kind of key status as TyCon or 
      DataCon or Class.  And got rid of IdCoreRule altogether.   
      It's all much more solid and uniform, but it meant touching
      a *lot* of modules.
      
      
      4. Allow instance decls in hs-boot files
      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      Allowing instance decls in hs-boot files is jolly useful, becuase
      in a big mutually-recursive bunch of data types, you want to give
      the instances with the data type declarations.  To achieve this
      
      * The hs-boot file makes a provisional name for the dict-fun, something
        like $fx9.
      
      * When checking the "mother module", we check that the instance
        declarations line up (by type) and generate bindings for the 
        boot dfuns, such as
      	$fx9 = $f2
        where $f2 is the dfun generated by the mother module
      
      * In doing this I decided that it's cleaner to have DFunIds get their
        final External Name at birth.  To do that they need a stable OccName,
        so I have an integer-valued dfun-name-supply in the TcM monad.
        That keeps it simple.
      
      This feature is hardly tested yet.
      
      
      5. Tidy up tidying, and Iface file generation
      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      main/TidyPgm now has two entry points:
      
        simpleTidyPgm is for hi-boot files, when typechecking only
        (not yet implemented), and potentially when compiling without -O.
        It ignores the bindings, and generates a nice small TypeEnv.
      
        optTidyPgm is the normal case: compiling with -O.  It generates a
        TypeEnv rich in IdInfo
      
      MkIface.mkIface now only generates a ModIface.  A separate
      procedure, MkIface.writeIfaceFile, writes the file out to disk.
      dd313897
  14. 31 Mar, 2005 1 commit
    • simonmar's avatar
      [project @ 2005-03-31 10:16:33 by simonmar] · 853e20a3
      simonmar authored
      Tweaks to get the GHC sources through Haddock.  Doesn't quite work
      yet, because Haddock complains about the recursive modules.  Haddock
      needs to understand SOURCE imports (it can probably just ignore them
      as a first attempt).
      853e20a3
  15. 30 Sep, 2004 1 commit
    • simonpj's avatar
      [project @ 2004-09-30 10:35:15 by simonpj] · 23f40f0e
      simonpj authored
      ------------------------------------
      	Add Generalised Algebraic Data Types
      	------------------------------------
      
      This rather big commit adds support for GADTs.  For example,
      
          data Term a where
       	  Lit :: Int -> Term Int
      	  App :: Term (a->b) -> Term a -> Term b
      	  If  :: Term Bool -> Term a -> Term a
      	  ..etc..
      
          eval :: Term a -> a
          eval (Lit i) = i
          eval (App a b) = eval a (eval b)
          eval (If p q r) | eval p    = eval q
          		    | otherwise = eval r
      
      
      Lots and lots of of related changes throughout the compiler to make
      this fit nicely.
      
      One important change, only loosely related to GADTs, is that skolem
      constants in the typechecker are genuinely immutable and constant, so
      we often get better error messages from the type checker.  See
      TcType.TcTyVarDetails.
      
      There's a new module types/Unify.lhs, which has purely-functional
      unification and matching for Type. This is used both in the typechecker
      (for type refinement of GADTs) and in Core Lint (also for type refinement).
      23f40f0e
  16. 26 Aug, 2004 1 commit
    • simonpj's avatar
      [project @ 2004-08-26 15:44:50 by simonpj] · bb88e732
      simonpj authored
      -------------------------------
      	Print built-in sytax right
      	-------------------------------
      
      Built-in syntax, like (:) and [], is not "in scope" via the GlobalRdrEnv
      in the usual way.  When we print it out, we should also print it in unqualified
      form, even though it's not in the environment.
      
      I've finally bitten the (not very big) bullet, and added to Name the information
      about whether or not a name is one of these built-in ones.  That entailed changing
      the calls to mkWiredInName, but those are exactly the places where you have to
      decide whether it's built-in or not, which is fine.
      
      
      Built-in syntax => It's a syntactic form, not "in scope" (e.g. [])
      
      Wired-in thing  => The thing (Id, TyCon) is fully known to the compiler,
      		   not read from an interface file.
      		   E.g. Bool, True, Int, Float, and many others
      
      All built-in syntax is for wired-in things.
      bb88e732
  17. 02 Jun, 2004 1 commit
    • simonpj's avatar
      [project @ 2004-06-02 08:25:10 by simonpj] · 729a6eb1
      simonpj authored
      -----------------------------------------------
             Record whether data constructors are declared infix
      	-----------------------------------------------
      
      This allows us to generate the InfixC form in Template Hasekll.
      And for 'deriving' Read and Show, we now read and parse the infix
      form iff the constructor was declared infix, rather than just if
      it does not have the default fixity (as before).
      
      IfaceSyn changes slightly, so that IfaceConDecl can record their
      fixity, so there are trivial changes scattered about, and
      you'll need to recompile everything.
      
      In TysWiredIn I took the opportunity to simplify pcDataCon slightly,
      by eliminating the unused Theta argument.
      729a6eb1
  18. 17 Mar, 2004 1 commit
    • simonpj's avatar
      [project @ 2004-03-17 13:59:06 by simonpj] · af5a2151
      simonpj authored
      ------------------------
      	More newtype clearing up
      	------------------------
      
      * Change the representation of TyCons so that it accurately reflects
      	* data     (0 or more constrs)
      	* newtype  (1 constr)
      	* abstract (unknown)
        Replaces DataConDetails and AlgTyConFlavour with AlgTyConRhs
      
      * Add IfaceSyn.IfaceConDecls, a kind of stripped-down analogue
        of AlgTyConRhs
      
      * Move NewOrData from BasicTypes to HsDecl (it's now an HsSyn thing)
      
      * Arrange that Type.newTypeRep and splitRecNewType_maybe unwrap just
        one layer of new-type-ness, leaving the caller to recurse.
      
        This still leaves typeRep and repType in Type.lhs; these functions
        are still vaguely disturbing and probably should get some attention.
      
      Lots of knock-on changes.  Fixes bug in ds054.
      af5a2151
  19. 30 Dec, 2003 1 commit
    • simonpj's avatar
      [project @ 2003-12-30 16:29:17 by simonpj] · f714e6b6
      simonpj authored
      ----------------------------
              Re-do kind inference (again)
      	----------------------------
      
         [WARNING: interface file binary representation has
         (as usual) changed slightly; recompile your libraries!]
      
      Inspired by the lambda-cube, for some time GHC has used
      	type Kind = Type
      That is, kinds were represented by the same data type as types.
      
      But GHC also supports unboxed types and unboxed tuples, and these
      complicate the kind system by requiring a sub-kind relationship.
      Notably, an unboxed tuple is acceptable as the *result* of a
      function but not as an *argument*.  So we have the following setup:
      
      		 ?
      		/ \
      	       /   \
      	      ??   (#)
      	     /  \
                  *   #
      
      where	*    [LiftedTypeKind]   means a lifted type
      	#    [UnliftedTypeKind] means an unlifted type
      	(#)  [UbxTupleKind]     means unboxed tuple
      	??   [ArgTypeKind]      is the lub of *,#
      	?    [OpenTypeKind]	means any type at all
      
      In particular:
      
        error :: forall a:?. String -> a
        (->)  :: ?? -> ? -> *
        (\(x::t) -> ...)	Here t::?? (i.e. not unboxed tuple)
      
      All this has beome rather difficult to accommodate with Kind=Type, so this
      commit splits the two.
      
        * Kind is a distinct type, defined in types/Kind.lhs
      
        * IfaceType.IfaceKind disappears: we just re-use Kind.Kind
      
        * TcUnify.unifyKind is a distinct unifier for kinds
      
        * TyCon no longer needs KindCon and SuperKindCon variants
      
        * TcUnify.zapExpectedType takes an expected Kind now, so that
          in TcPat.tcMonoPatBndr we can express that the bound variable
          must have an argTypeKind (??).
      
      The big change is really that kind inference is much more systematic and
      well behaved.  In particular, a kind variable can unify only with a
      "simple kind", which is built from * and (->).  This deals neatly
      with awkward questions about how we can combine sub-kinding with type
      inference.
      
      Lots of small consequential changes, especially to the kind-checking
      plumbing in TcTyClsDecls.  (We played a bit fast and loose before, and
      now we have to be more honest, in particular about how kind inference
      works for type synonyms.  They can have kinds like (* -> #), so
      
      This cures two long-standing SourceForge bugs
      
      * 753777 (tcfail115.hs), which used erroneously to pass,
        but crashed in the code generator
            type T a = Int -> (# Int, Int #)
            f :: T a -> T a
            f t = \x -> case t x of r -> r
      
      * 753780 (tc167.hs), which used erroneously to fail
            f :: (->) Int# Int#
      
      
      Still, the result is not entirely satisfactory.  In particular
      
      * The error message from tcfail115 is pretty obscure
      
      * SourceForge bug 807249 (Instance match failure on openTypeKind)
        is not fixed.  Alas.
      f714e6b6
  20. 09 Oct, 2003 1 commit
    • simonpj's avatar
      [project @ 2003-10-09 11:58:39 by simonpj] · 98688c6e
      simonpj authored
      -------------------------
      		GHC heart/lung transplant
      		-------------------------
      
      This major commit changes the way that GHC deals with importing
      types and functions defined in other modules, during renaming and
      typechecking.  On the way I've changed or cleaned up numerous other
      things, including many that I probably fail to mention here.
      
      Major benefit: GHC should suck in many fewer interface files when
      compiling (esp with -O).  (You can see this with -ddump-rn-stats.)
      
      It's also some 1500 lines of code shorter than before.
      
      **	So expect bugs!  I can do a 3-stage bootstrap, and run
      **	the test suite, but you may be doing stuff I havn't tested.
      ** 	Don't update if you are relying on a working HEAD.
      
      
      In particular, (a) External Core and (b) GHCi are very little tested.
      
      	But please, please DO test this version!
      
      
      	------------------------
      		Big things
      	------------------------
      
      Interface files, version control, and importing declarations
      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      * There is a totally new data type for stuff that lives in interface files:
      	Original names			IfaceType.IfaceExtName
      	Types				IfaceType.IfaceType
      	Declarations (type,class,id)	IfaceSyn.IfaceDecl
      	Unfoldings			IfaceSyn.IfaceExpr
        (Previously we used HsSyn for type/class decls, and UfExpr for unfoldings.)
        The new data types are in iface/IfaceType and iface/IfaceSyn.  They are
        all instances of Binary, so they can be written into interface files.
        Previous engronkulation concering the binary instance of RdrName has
        gone away -- RdrName is not an instance of Binary any more.  Nor does
        Binary.lhs need to know about the ``current module'' which it used to,
        which made it specialised to GHC.
      
        A good feature of this is that the type checker for source code doesn't
        need to worry about the possibility that we might be typechecking interface
        file stuff.  Nor does it need to do renaming; we can typecheck direct from
        IfaceSyn, saving a whole pass (module TcIface)
      
      * Stuff from interface files is sucked in *lazily*, rather than being eagerly
        sucked in by the renamer. Instead, we use unsafeInterleaveIO to capture
        a thunk for the unfolding of an imported function (say).  If that unfolding
        is every pulled on, TcIface will scramble over the unfolding, which may
        in turn pull in the interface files of things mentioned in the unfolding.
      
        The External Package State is held in a mutable variable so that it
        can be side-effected by this lazy-sucking-in process (which may happen
        way later, e.g. when the simplifier runs).   In effect, the EPS is a kind
        of lazy memo table, filled in as we suck things in.  Or you could think
        of it as a global symbol table, populated on demand.
      
      * This lazy sucking is very cool, but it can lead to truly awful bugs. The
        intent is that updates to the symbol table happen atomically, but very bad
        things happen if you read the variable for the table, and then force a
        thunk which updates the table.  Updates can get lost that way. I regret
        this subtlety.
      
        One example of the way it showed up is that the top level of TidyPgm
        (which updates the global name cache) to be much more disciplined about
        those updates, since TidyPgm may itself force thunks which allocate new
        names.
      
      * Version numbering in interface files has changed completely, fixing
        one major bug with ghc --make.  Previously, the version of A.f changed
        only if A.f's type and unfolding was textually different.  That missed
        changes to things that A.f's unfolding mentions; which was fixed by
        eagerly sucking in all of those things, and listing them in the module's
        usage list.  But that didn't work with --make, because they might have
        been already sucked in.
      
        Now, A.f's version changes if anything reachable from A.f (via interface
        files) changes.  A module with unchanged source code needs recompiling
        only if the versions of any of its free variables changes. [This isn't
        quite right for dictionary functions and rules, which aren't mentioned
        explicitly in the source.  There are extensive comments in module MkIface,
        where all version-handling stuff is done.]
      
      * We don't need equality on HsDecls any more (because they aren't used in
        interface files).  Instead we have a specialised equality for IfaceSyn
        (eqIfDecl etc), which uses IfaceEq instead of Bool as its result type.
        See notes in IfaceSyn.
      
      * The horrid bit of the renamer that tried to predict what instance decls
        would be needed has gone entirely.  Instead, the type checker simply
        sucks in whatever instance decls it needs, when it needs them.  Easy!
      
        Similarly, no need for 'implicitModuleFVs' and 'implicitTemplateHaskellFVs'
        etc.  Hooray!
      
      
      Types and type checking
      ~~~~~~~~~~~~~~~~~~~~~~~
      * Kind-checking of types is far far tidier (new module TcHsTypes replaces
        the badly-named TcMonoType).  Strangely, this was one of my
        original goals, because the kind check for types is the Right Place to
        do type splicing, but it just didn't fit there before.
      
      * There's a new representation for newtypes in TypeRep.lhs.  Previously
        they were represented using "SourceTypes" which was a funny compromise.
        Now they have their own constructor in the Type datatype.  SourceType
        has turned back into PredType, which is what it used to be.
      
      * Instance decl overlap checking done lazily.  Consider
      	instance C Int b
      	instance C a Int
        These were rejected before as overlapping, because when seeking
        (C Int Int) one couldn't tell which to use.  But there's no problem when
        seeking (C Bool Int); it can only be the second.
      
        So instead of checking for overlap when adding a new instance declaration,
        we check for overlap when looking up an Inst.  If we find more than one
        matching instance, we see if any of the candidates dominates the others
        (in the sense of being a substitution instance of all the others);
        and only if not do we report an error.
      
      
      
      	------------------------
      	     Medium things
      	------------------------
      
      * The TcRn monad is generalised a bit further.  It's now based on utils/IOEnv.lhs,
        the IO monad with an environment.  The desugarer uses the monad too,
        so that anything it needs can get faulted in nicely.
      
      * Reduce the number of wired-in things; in particular Word and Integer
        are no longer wired in.  The latter required HsLit.HsInteger to get a
        Type argument.  The 'derivable type classes' data types (:+:, :*: etc)
        are not wired in any more either (see stuff about derivable type classes
        below).
      
      * The PersistentComilerState is now held in a mutable variable
        in the HscEnv.  Previously (a) it was passed to and then returned by
        many top-level functions, which was painful; (b) it was invariably
        accompanied by the HscEnv.  This change tidies up top-level plumbing
        without changing anything important.
      
      * Derivable type classes are treated much more like 'deriving' clauses.
        Previously, the Ids for the to/from functions lived inside the TyCon,
        but now the TyCon simply records their existence (with a simple boolean).
        Anyone who wants to use them must look them up in the environment.
      
        This in turn makes it easy to generate the to/from functions (done
        in types/Generics) using HsSyn (like TcGenDeriv for ordinary derivings)
        instead of CoreSyn, which in turn means that (a) we don't have to figure
        out all the type arguments etc; and (b) it'll be type-checked for us.
        Generally, the task of generating the code has become easier, which is
        good for Manuel, who wants to make it more sophisticated.
      
      * A Name now says what its "parent" is. For example, the parent of a data
        constructor is its type constructor; the parent of a class op is its
        class.  This relationship corresponds exactly to the Avail data type;
        there may be other places we can exploit it.  (I made the change so that
        version comparison in interface files would be a bit easier; but in
        fact it tided up other things here and there (see calls to
        Name.nameParent).  For example, the declaration pool, of declararations
        read from interface files, but not yet used, is now keyed only by the 'main'
        name of the declaration, not the subordinate names.
      
      * New types OccEnv and OccSet, with the usual operations.
        OccNames can be efficiently compared, because they have uniques, thanks
        to the hashing implementation of FastStrings.
      
      * The GlobalRdrEnv is now keyed by OccName rather than RdrName.  Not only
        does this halve the size of the env (because we don't need both qualified
        and unqualified versions in the env), but it's also more efficient because
        we can use a UniqFM instead of a FiniteMap.
      
        Consequential changes to Provenance, which has moved to RdrName.
      
      * External Core remains a bit of a hack, as it was before, done with a mixture
        of HsDecls (so that recursiveness and argument variance is still inferred),
        and IfaceExprs (for value declarations).  It's not thoroughly tested.
      
      
      	------------------------
      	     Minor things
      	------------------------
      
      * DataCon fields dcWorkId, dcWrapId combined into a single field
        dcIds, that is explicit about whether the data con is a newtype or not.
        MkId.mkDataConWorkId and mkDataConWrapId are similarly combined into
        MkId.mkDataConIds
      
      * Choosing the boxing strategy is done for *source* type decls only, and
        hence is now in TcTyDecls, not DataCon.
      
      * WiredIn names are distinguished by their n_sort field, not by their location,
        which was rather strange
      
      * Define Maybes.mapCatMaybes :: (a -> Maybe b) -> [a] -> [b]
        and use it here and there
      
      * Much better pretty-printing of interface files (--show-iface)
      
      Many, many other small things.
      
      
      	------------------------
      	     File changes
      	------------------------
      * New iface/ subdirectory
      * Much of RnEnv has moved to iface/IfaceEnv
      * MkIface and BinIface have moved from main/ to iface/
      * types/Variance has been absorbed into typecheck/TcTyDecls
      * RnHiFiles and RnIfaces have vanished entirely.  Their
        work is done by iface/LoadIface
      * hsSyn/HsCore has gone, replaced by iface/IfaceSyn
      * typecheck/TcIfaceSig has gone, replaced by iface/TcIface
      * typecheck/TcMonoType has been renamed to typecheck/TcHsType
      * basicTypes/Var.hi-boot and basicTypes/Generics.hi-boot have gone altogether
      98688c6e
  21. 16 Jun, 2003 1 commit
    • simonpj's avatar
      [project @ 2003-06-16 15:32:16 by simonpj] · f5fbd41c
      simonpj authored
      --------------------------
      	Remove some wired-in types
      	--------------------------
      
      ptrTyCon, funPtrTyCon, addrTyCon, stablePtrTyCon have no business
      being wired in. This commit makes them into knownKey Names, which
      is much better.
      f5fbd41c
  22. 03 Mar, 2003 1 commit
  23. 21 Feb, 2003 1 commit
    • simonpj's avatar
      [project @ 2003-02-21 13:27:53 by simonpj] · 84ed91ab
      simonpj authored
      -------------------------------------
      	Improve the "unused binding" warnings
      	-------------------------------------
      
      We've had a succession of hacks for reporting warnings for
      unused bindings.  Consider
      
      	module M( f ) where
      
       	f x = x
      
      	g x = g x + h x
      	h x = x
      
      Here, g mentions itself and h, but is not itself mentioned. So
      really both g and h are dead code.  We've been getting this wrong
      for ages, and every hack so far has failed on some simple programs.
      
      This commit does a much better job.  The renamer applied to a bunch
      of bindings returns a NameSet.DefUses, which is a dependency-ordered
      lists of def/use pairs.  It's documented in NameSet.
      Given this, we can work out precisely what is not used, in a nice
      tidy way.
      
      It's less convenient in the case of type and class declarations, because
      the strongly-connected-component analysis can span module boundaries.
      So things are pretty much as they were for these.
      
      
      As usual, there was a lot of chuffing around tidying things up.
      I havn't tested it at all thoroughly yet.
      
      Various unrelated import-decl-pruning has been done too.
      84ed91ab
  24. 12 Feb, 2003 1 commit
    • simonpj's avatar
      [project @ 2003-02-12 15:01:31 by simonpj] · 42b63073
      simonpj authored
      -------------------------------------
        Big upheaval to the way that constructors are named
      	-------------------------------------
      
      This commit enshrines the new story for constructor names.  We could never
      really get External Core to work nicely before, but now it does.
      
      The story is laid out in detail in the Commentary
      	ghc/docs/comm/the-beast/data-types.html
      so I will not repeat it here.
      
      	[Manuel: the commentary isn't being updated, apparently.]
      
      However, the net effect is that in Core and in External Core, contructors look
      like constructors, and the way things are printed is all consistent.
      
      It is a fairly pervasive change (which is why it has been so long postponed),
      but I hope the question is now finally closed.
      
      All the libraries compile etc, and I've run many tests, but doubtless there will
      be some dark corners.
      42b63073
  25. 24 Oct, 2002 1 commit
    • simonpj's avatar
      [project @ 2002-10-24 14:17:46 by simonpj] · e0445ffa
      simonpj authored
      ------------------------------------------
      	1. New try and module and package dependencies
      	2. OrigNameCache always contains final info
      	------------------------------------------
      
      These things nearly complete sorting out the incremental
      linking problem that started us off!
      
      1. This commit separates two kinds of information:
      
        (a) HscTypes.Dependencies:
      	What (i)  home-package modules, and
      	     (ii) other packages
            this module depends on, transitively.
      
            That is, to link the module, it should be enough
            to link the dependent modules and packages (plus
            any C stubs etc).
      
            Along with this info we record whether the dependent module
            is (a) a boot interface or (b) an orphan module.  So in
            fact (i) can contain non-home-package modules, namely the
            orphan ones in other packages (sigh).
      
        (b) HscTypes.Usage:
            What version of imported things were used to
            actually compile the module.  This info is used for
            recompilation control only.
      
      
      
      2. The Finder now returns a correct Module (incl package indicator)
      first time, so we can install the absolutely final Name in the
      OrigNameCache when we first come across an occurrence of that name,
      even if it's only an occurrence in an unfolding in some other interface
      file.  This is much tidier.
      
      As a result Module.lhs is much cleaner
      	No DunnoYet
      	No mkVanillaModule
      ALl very joyful stuff.
      e0445ffa
  26. 13 Sep, 2002 1 commit
    • simonpj's avatar
      [project @ 2002-09-13 15:02:25 by simonpj] · 9af77fa4
      simonpj authored
      --------------------------------------
      	Make Template Haskell into the HEAD
      	--------------------------------------
      
      This massive commit transfers to the HEAD all the stuff that
      Simon and Tim have been doing on Template Haskell.  The
      meta-haskell-branch is no more!
      
      WARNING: make sure that you
      
        * Update your links if you are using link trees.
          Some modules have been added, some have gone away.
      
        * Do 'make clean' in all library trees.
          The interface file format has changed, and you can
          get strange panics (sadly) if GHC tries to read old interface files:
          e.g.  ghc-5.05: panic! (the `impossible' happened, GHC version 5.05):
      	  Binary.get(TyClDecl): ForeignType
      
        * You need to recompile the rts too; Linker.c has changed
      
      
      However the libraries are almost unaltered; just a tiny change in
      Base, and to the exports in Prelude.
      
      
      NOTE: so far as TH itself is concerned, expression splices work
      fine, but declaration splices are not complete.
      
      
      		---------------
      		The main change
      		---------------
      
      The main structural change: renaming and typechecking have to be
      interleaved, because we can't rename stuff after a declaration splice
      until after we've typechecked the stuff before (and the splice
      itself).
      
      * Combine the renamer and typecheker monads into one
      	(TcRnMonad, TcRnTypes)
        These two replace TcMonad and RnMonad
      
      * Give them a single 'driver' (TcRnDriver).  This driver
        replaces TcModule.lhs and Rename.lhs
      
      * The haskell-src library package has a module
      	Language/Haskell/THSyntax
        which defines the Haskell data type seen by the TH programmer.
      
      * New modules:
      	hsSyn/Convert.hs 	converts THSyntax -> HsSyn
      	deSugar/DsMeta.hs 	converts HsSyn -> THSyntax
      
      * New module typecheck/TcSplice type-checks Template Haskell splices.
      
      		-------------
      		Linking stuff
      		-------------
      
      * ByteCodeLink has been split into
      	ByteCodeLink	(which links)
      	ByteCodeAsm	(which assembles)
      
      * New module ghci/ObjLink is the object-code linker.
      
      * compMan/CmLink is removed entirely (was out of place)
        Ditto CmTypes (which was tiny)
      
      * Linker.c initialises the linker when it is first used (no need to call
        initLinker any more).  Template Haskell makes it harder to know when
        and whether to initialise the linker.
      
      
      	-------------------------------------
      	Gathering the LIE in the type checker
      	-------------------------------------
      
      * Instead of explicitly gathering constraints in the LIE
      	tcExpr :: RenamedExpr -> TcM (TypecheckedExpr, LIE)
        we now dump the constraints into a mutable varabiable carried
        by the monad, so we get
      	tcExpr :: RenamedExpr -> TcM TypecheckedExpr
      
        Much less clutter in the code, and more efficient too.
        (Originally suggested by Mark Shields.)
      
      
      		-----------------
      		Remove "SysNames"
      		-----------------
      
      Because the renamer and the type checker were entirely separate,
      we had to carry some rather tiresome implicit binders (or "SysNames")
      along inside some of the HsDecl data structures.  They were both
      tiresome and fragile.
      
      Now that the typechecker and renamer are more intimately coupled,
      we can eliminate SysNames (well, mostly... default methods still
      carry something similar).
      
      		-------------
      		Clean up HsPat
      		-------------
      
      One big clean up is this: instead of having two HsPat types (InPat and
      OutPat), they are now combined into one.  This is more consistent with
      the way that HsExpr etc is handled; there are some 'Out' constructors
      for the type checker output.
      
      So:
      	HsPat.InPat	--> HsPat.Pat
      	HsPat.OutPat	--> HsPat.Pat
      	No 'pat' type parameter in HsExpr, HsBinds, etc
      
      	Constructor patterns are nicer now: they use
      		HsPat.HsConDetails
      	for the three cases of constructor patterns:
      		prefix, infix, and record-bindings
      
      	The *same* data type HsConDetails is used in the type
      	declaration of the data type (HsDecls.TyData)
      
      Lots of associated clean-up operations here and there.  Less code.
      Everything is wonderful.
      9af77fa4
  27. 06 Sep, 2002 1 commit
  28. 29 Apr, 2002 1 commit
    • simonmar's avatar
      [project @ 2002-04-29 14:03:38 by simonmar] · b085ee40
      simonmar authored
      FastString cleanup, stage 1.
      
      The FastString type is no longer a mixture of hashed strings and
      literal strings, it contains hashed strings only with O(1) comparison
      (except for UnicodeStr, but that will also go away in due course).  To
      create a literal instance of FastString, use FSLIT("..").
      
      By far the most common use of the old literal version of FastString
      was in the pattern
      
      	  ptext SLIT("...")
      
      this combination still works, although it doesn't go via FastString
      any more.  The next stage will be to remove the need to use this
      special combination at all, using a RULE.
      
      To convert a FastString into an SDoc, now use 'ftext' instead of
      'ptext'.
      
      I've also removed all the FAST_STRING related macros from HsVersions.h
      except for SLIT and FSLIT, just use the relevant functions from
      FastString instead.
      b085ee40
  29. 01 Apr, 2002 1 commit
    • simonpj's avatar
      [project @ 2002-04-01 08:23:30 by simonpj] · 9003a18c
      simonpj authored
      ------------------------------------
      	Change the treatment of the stupid
      	   context on data constructors
      	-----------------------------------
      
      Data types can have a context:
      
      	data (Eq a, Ord b) => T a b = T1 a b | T2 a
      
      and that makes the constructors have a context too
      (notice that T2's context is "thinned"):
      
      	T1 :: (Eq a, Ord b) => a -> b -> T a b
      	T2 :: (Eq a) => a -> T a b
      
      Furthermore, this context pops up when pattern matching
      (though GHC hasn't implemented this, but it is in H98, and
      I've fixed GHC so that it now does):
      
      	f (T2 x) = x
      gets inferred type
      	f :: Eq a => T a b -> a
      
      I say the context is "stupid" because the dictionaries passed
      are immediately discarded -- they do nothing and have no benefit.
      It's a flaw in the language.
      
      Up to now I have put this stupid context into the type of
      the "wrapper" constructors functions, T1 and T2, but that turned
      out to be jolly inconvenient for generics, and record update, and
      other functions that build values of type T (because they don't
      have suitable dictionaries available).
      
      So now I've taken the stupid context out.  I simply deal with
      it separately in the type checker on occurrences of a constructor,
      either in an expression or in a pattern.
      
      To this end
      
      * Lots of changes in DataCon, MkId
      
      * New function Inst.tcInstDataCon to instantiate a data constructor
      
      
      
      I also took the opportunity to
      
      * Rename
      	dataConId --> dataConWorkId
        for consistency.
      
      * Tidied up MkId.rebuildConArgs quite a bit, and renamed it
      	mkReboxingAlt
      
      * Add function DataCon.dataConExistentialTyVars, with the obvious meaning
      9003a18c
  30. 13 Feb, 2002 1 commit
    • simonpj's avatar
      [project @ 2002-02-13 15:19:17 by simonpj] · 711e4d7a
      simonpj authored
      ----------------------------------
      	Do the Right Thing for TyCons where we
      	can't see all their constructors.
      	----------------------------------
      
      Inside a TyCon, three things can happen
      
      1. GHC knows all the constructors, and has them to hand.
         (Nowadays, there may be zero constructors.)
      
      2. GHC knows all the constructors, but has declined to slurp
         them all in, to avoid sucking in more declarations than
         necessary.  All we remember is the number of constructors,
         so we can get the return convention right.
      
      3. GHC doesn't know anything. This happens *only* for decls
         coming from .hi-boot files, where the programmer declines to
         supply a representation.
      
      Until now, these three cases have been conflated together.  Matters
      are worse now that a TyCon really can have zero constructors.  In
      fact, by confusing (3) with (1) we can actually generate bogus code.
      
      With this commit, the dataCons field of a TyCon is of type:
      
      data DataConDetails datacon
        = DataCons [datacon]	-- Its data constructors, with fully polymorphic types
      			-- A type can have zero constructors
      
        | Unknown		-- We're importing this data type from an hi-boot file
      			-- and we don't know what its constructors are
      
        | HasCons Int		-- In a quest for compilation speed we have imported
      			-- only the number of constructors (to get return
      			-- conventions right) but not the constructors themselves
      
      This says exactly what is going on.  There are lots of consequential small
      changes.
      711e4d7a
  31. 11 Feb, 2002 1 commit
    • chak's avatar
      [project @ 2002-02-11 08:20:38 by chak] · 10fcd78c
      chak authored
      *******************************
      		       * Merging from ghc-ndp-branch *
      		       *******************************
      
      This commit merges the current state of the "parallel array extension" and
      includes the following:
      
      * (Almost) completed Milestone 1:
        - The option `-fparr' activates the H98 extension for parallel arrays.
        - These changes have a high likelihood of conflicting (in the CVS sense)
          with other changes to GHC and are the reason for merging now.
        - ToDo: There are still some (less often used) functions not implemented in
      	  `PrelPArr' and a mechanism is needed to automatically import
      	  `PrelPArr' iff `-fparr' is given.  Documentation that should go into
      	  the Commentary is currently in `ghc/compiler/ndpFlatten/TODO'.
      
      * Partial Milestone 2:
        - The option `-fflatten' activates the flattening transformation and `-ndp'
          selects the "ndp" way (where all libraries have to be compiled with
          flattening).  The way option `-ndp' automagically turns on `-fparr' and
          `-fflatten'.
        - Almost all changes are in the new directory `ndpFlatten' and shouldn't
          affect the rest of the compiler.  The only exception are the options and
          the points in `HscMain' where the flattening phase is called when
          `-fflatten' is given.
        - This isn't usable yet, but already implements function lifting,
          vectorisation, and a new analysis that determines which parts of a module
          have to undergo the flattening transformation.  Missing are data structure
          and function specialisation, the unboxed array library (including fusion
          rules), and lots of testing.
      
      I have just run the regression tests on the thing without any problems.  So,
      it seems, as if we haven't broken anything crucial.
      10fcd78c
  32. 26 Nov, 2001 1 commit
    • simonpj's avatar
      [project @ 2001-11-26 09:20:25 by simonpj] · 5e3f005d
      simonpj authored
      ----------------------
      	Implement Rank-N types
      	----------------------
      
      This commit implements the full glory of Rank-N types, using
      the Odersky/Laufer approach described in their paper
      	"Putting type annotations to work"
      
      In fact, I've had to adapt their approach to deal with the
      full glory of Haskell (including pattern matching, and the
      scoped-type-variable extension).  However, the result is:
      
      * There is no restriction to rank-2 types.  You can nest forall's
        as deep as you like in a type.  For example, you can write a type
        like
      	p :: ((forall a. Eq a => a->a) -> Int) -> Int
        This is a rank-3 type, illegal in GHC 5.02
      
      * When matching types, GHC uses the cunning Odersky/Laufer coercion
        rules.  For example, suppose we have
      	q :: (forall c. Ord c => c->c) -> Int
        Then, is this well typed?
      	x :: Int
      	x = p q
        Yes, it is, but GHC has to generate the right coercion.  Here's
        what it looks like with all the big lambdas and dictionaries put in:
      
      	x = p (\ f :: (forall a. Eq a => a->a) ->
      		 q (/\c \d::Ord c -> f c (eqFromOrd d)))
      
        where eqFromOrd selects the Eq superclass dictionary from the Ord
        dicationary:		eqFromOrd :: Ord a -> Eq a
      
      
      * You can use polymorphic types in pattern type signatures.  For
        example:
      
      	f (g :: forall a. a->a) = (g 'c', g True)
      
        (Previously, pattern type signatures had to be monotypes.)
      
      * The basic rule for using rank-N types is that you must specify
        a type signature for every binder that you want to have a type
        scheme (as opposed to a plain monotype) as its type.
      
        However, you don't need to give the type signature on the
        binder (as I did above in the defn for f).  You can give it
        in a separate type signature, thus:
      
      	f :: (forall a. a->a) -> (Char,Bool)
      	f g = (g 'c', g True)
      
        GHC will push the external type signature inwards, and use
        that information to decorate the binders as it comes across them.
        I don't have a *precise* specification of this process, but I
        think it is obvious enough in practice.
      
      * In a type synonym you can use rank-N types too.  For example,
        you can write
      
      	type IdFun = forall a. a->a
      
      	f :: IdFun -> (Char,Bool)
      	f g = (g 'c', g True)
      
        As always, type synonyms must always occur saturated; GHC
        expands them before it does anything else.  (Still, GHC goes
        to some trouble to keep them unexpanded in error message.)
      
      
      The main plan is as before.  The main typechecker for expressions,
      tcExpr, takes an "expected type" as its argument.  This greatly
      improves error messages.  The new feature is that when this
      "expected type" (going down) meets an "actual type" (coming up)
      we use the new subsumption function
      	TcUnify.tcSub
      which checks that the actual type can be coerced into the
      expected type (and produces a coercion function to demonstrate).
      
      The main new chunk of code is TcUnify.tcSub.  The unifier itself
      is unchanged, but it has moved from TcMType into TcUnify.  Also
      checkSigTyVars has moved from TcMonoType into TcUnify.
      Result: the new module, TcUnify, contains all stuff relevant
      to subsumption and unification.
      
      Unfortunately, there is now an inevitable loop between TcUnify
      and TcSimplify, but that's just too bad (a simple TcUnify.hi-boot
      file).
      
      
      All of this doesn't come entirely for free.  Here's the typechecker
      line count (INCLUDING comments)
      	Before	16,551
      	After	17,116
      5e3f005d
  33. 06 Sep, 2001 1 commit
  34. 28 Aug, 2001 1 commit
    • simonpj's avatar
      [project @ 2001-08-28 10:06:29 by simonpj] · b0604aad
      simonpj authored
      ----------------------------------------
      	Make isFFIArgumentTy understand newtypes
      	----------------------------------------
      
      This fixes the bug Manuel reported:
      
      	newtype T = T (Ptr T)
      	foreign import ccall foo :: T -> IO (Ptr T)
      
        test.hs:6:
            Unacceptable argument type in foreign declaration: T
      
      
      On the way, I moved isFFIArgumentTy and friends out of TysWiredIn,
      where they didn't really belong, into TcType.  That in turn force
      me to move isStrictType, and isPrimitiveType.
      b0604aad
  35. 23 Jul, 2001 1 commit
    • simonpj's avatar
      [project @ 2001-07-23 10:54:46 by simonpj] · f6cd95ff
      simonpj authored
      ---------------------------------
      	Switch to the new demand analyser
      	---------------------------------
      
      This commit makes the new demand analyser the main beast,
      with the old strictness analyser as a backup.  When
      DEBUG is on, the old strictness analyser is run too, and the
      results compared.
      
      WARNING: this isn't thorougly tested yet, so expect glitches.
      Delay updating for a few days if the HEAD is mission critical
      for you.
      
      But do try it out.  I'm away for 2.5 weeks from Thursday, so
      it would be good to shake out any glaring bugs before then.
      f6cd95ff
  36. 25 Jun, 2001 1 commit
    • simonpj's avatar
      [project @ 2001-06-25 08:09:57 by simonpj] · d069cec2
      simonpj authored
      ----------------
      	Squash newtypes
      	----------------
      
      This commit squashes newtypes and their coerces, from the typechecker
      onwards.  The original idea was that the coerces would not get in the
      way of optimising transformations, but despite much effort they continue
      to do so.   There's no very good reason to retain newtype information
      beyond the typechecker, so now we don't.
      
      Main points:
      
      * The post-typechecker suite of Type-manipulating functions is in
      types/Type.lhs, as before.   But now there's a new suite in types/TcType.lhs.
      The difference is that in the former, newtype are transparent, while in
      the latter they are opaque.  The typechecker should only import TcType,
      not Type.
      
      * The operations in TcType are all non-monadic, and most of them start with
      "tc" (e.g. tcSplitTyConApp).  All the monadic operations (used exclusively
      by the typechecker) are in a new module, typecheck/TcMType.lhs
      
      * I've grouped newtypes with predicate types, thus:
      	data Type = TyVarTy Tyvar | ....
      		  | SourceTy SourceType
      
      	data SourceType = NType TyCon [Type]
      			| ClassP Class [Type]
      			| IParam Type
      
      [SourceType was called PredType.]  This is a little wierd in some ways,
      because NTypes can't occur in qualified types.   However, the idea is that
      a SourceType is a type that is opaque to the type checker, but transparent
      to the rest of the compiler, and newtypes fit that as do implicit parameters
      and dictionaries.
      
      * Recursive newtypes still retain their coreces, exactly as before. If
      they were transparent we'd get a recursive type, and that would make
      various bits of the compiler diverge (e.g. things which do type comparison).
      
      * I've removed types/Unify.lhs (non-monadic type unifier and matcher),
      merging it into TcType.
      
      Ditto typecheck/TcUnify.lhs (monadic unifier), merging it into TcMType.
      d069cec2
  37. 22 May, 2001 1 commit
    • simonpj's avatar
      [project @ 2001-05-22 13:43:14 by simonpj] · f16228e4
      simonpj authored
      -------------------------------------------
      	Towards generalising 'foreign' declarations
      	-------------------------------------------
      
      This is a first step towards generalising 'foreign' declarations to
      handle langauges other than C.  Quite a lot of files are touched,
      but nothing has really changed.  Everything should work exactly as
      before.
      
      	But please be on your guard for ccall-related bugs.
      
      Main things
      
      Basic data types: ForeignCall.lhs
      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      * Remove absCSyn/CallConv.lhs
      
      * Add prelude/ForeignCall.lhs.  This defines the ForeignCall
        type and its variants
      
      * Define ForeignCall.Safety to say whether a call is unsafe
        or not (was just a boolean).  Lots of consequential chuffing.
      
      * Remove all CCall stuff from PrimOp, and put it in ForeignCall
      
      
      Take CCallOp out of the PrimOp type (where it was always a glitch)
      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      * Add IdInfo.FCallId variant to the type IdInfo.GlobalIdDetails,
      	along with predicates Id.isFCallId, Id.isFCallId_maybe
      
      * Add StgSyn.StgOp, to sum PrimOp with FCallOp, because it
        *is* useful to sum them together in Stg and AbsC land.  If
        nothing else, it minimises changes.
      
      
      Also generally rename "CCall" stuff to "FCall" where it's generic
      to all foreign calls.
      f16228e4
  38. 18 May, 2001 1 commit
    • simonpj's avatar
      [project @ 2001-05-18 08:46:18 by simonpj] · b4775e5e
      simonpj authored
      -----------------------------
      	Get unbox-strict-fields right
      	-----------------------------
      
      The problem was that when a library was compiled *without* -funbox-strict-fields,
      and the main program was compiled *with* that flag, we were wrongly treating
      the fields of imported data types as unboxed.
      
      To fix this I added an extra constructor to StrictnessMark to express whether
      the "!" annotation came from an interface file (don't fiddle) or a source
      file (decide whether to unbox).
      
      On the way I tided things up:
      
      * StrictnessMark moves to Demand.lhs, and doesn't have the extra DataCon
        fields that kept it in DataCon before.
      
      * HsDecls.BangType has one constructor, not three, with a StrictnessMark field.
      
      * DataCon keeps track of its strictness signature (dcRepStrictness), but not
        its "user strict marks" (which were never used)
      
      * All the functions, like getUniquesDs, that used to take an Int saying how
        many uniques to allocate, now return an infinite list. This saves arguments
        and hassle.  But it involved touching quite a few files.
      
      * rebuildConArgs takes a list of Uniques to use as its unique supply.  This
        means I could combine DsUtils.rebuildConArgs with MkId.rebuildConArgs
        (hooray; the main point of the previous change)
      
      
      I also tidied up one or two error messages
      b4775e5e
  39. 04 May, 2001 1 commit