1. 10 Sep, 2007 1 commit
    • Simon Marlow's avatar
      FIX #903: mkWWcpr: not a product · 3b1438a9
      Simon Marlow authored
      This fixes the long-standing bug that prevents some code with
      mutally-recursive modules from being compiled with --make and -O,
      including GHC itself.  See the comments for details.
      There are some additional cleanups that were forced/enabled by this
      patch: I removed importedSrcLoc/importedSrcSpan: it wasn't adding any
      useful information, since a Name already contains its defining Module.
      In fact when re-typechecking an interface file we were wrongly
      replacing the interesting SrcSpans in the Names with boring
      importedSrcSpans, which meant that location information could degrade
      after reloading modules.  Also, recreating all these Names was a waste
      of space/time.
  2. 06 Sep, 2007 1 commit
    • Simon Marlow's avatar
      FIX #1465, error messages could sometimes say things like "A.T doesn't match A.T" · 42181975
      Simon Marlow authored
      This turned out to be a black hole, however we believe we now have a
      plan that does the right thing and shouldn't need to change again.
      Error messages will only ever refer to a name in an unambiguous way,
      falling back to <package>:<module>.<name> if no unambiguous shorter
      variant can be found.  See HscTypes.mkPrintUnqualified for the
      Earlier hacks to work around this problem have been removed (TcSimplify).
  3. 04 Sep, 2007 1 commit
  4. 03 Sep, 2007 1 commit
  5. 01 Sep, 2007 1 commit
  6. 11 May, 2007 1 commit
  7. 25 Apr, 2007 1 commit
  8. 29 Nov, 2006 1 commit
    • andy@galois.com's avatar
      TickBox representation change · 8100cd43
      andy@galois.com authored
      This changes the internal representation of TickBoxes,
              Note (TickBox "module" n)  <expr>
              case tick<module,n> of
                _ -> <expr>
      tick has type :: #State #World, when the module and tick numbe
      are stored inside IdInfo.
      Binary tick boxes change from
               Note (BinaryTickBox "module" t f) <expr>
                btick<module,t,f> <expr>
      btick has type :: Bool -> Bool, with the module and tick number
      stored inside IdInfo.
  9. 11 Oct, 2006 2 commits
    • Simon Marlow's avatar
      Module header tidyup, phase 1 · 49c98d14
      Simon Marlow authored
      This patch is a start on removing import lists and generally tidying
      up the top of each module.  In addition to removing import lists:
         - Change DATA.IOREF -> Data.IORef etc.
         - Change List -> Data.List etc.
         - Remove $Id$
         - Update copyrights
         - Re-order imports to put non-GHC imports last
         - Remove some unused and duplicate imports
    • 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
          * 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.
         - 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.
  10. 18 Sep, 2006 1 commit
    • chak@cse.unsw.edu.au.'s avatar
      Type tags in import/export lists · 0cfba505
      chak@cse.unsw.edu.au. authored
      Tue Sep 12 16:57:32 EDT 2006  Manuel M T Chakravarty <chak@cse.unsw.edu.au>
        * Type tags in import/export lists
        - To write something like GMapKey(type GMap, empty, lookup, insert)
        - Requires -findexed-types
  11. 25 Jul, 2006 2 commits
    • Simon Marlow's avatar
      Unbox the Unique stored in a Name · ddb04482
      Simon Marlow authored
      I measured that this makes the comiler allocate a bit more, but it
      might also make it faster and reduce residency.  The extra allocation
      is probably just because we're not inlining enough somewhere, so I
      think this change is a step in the right direction.
    • 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.
  12. 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.
  13. 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.
  14. 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.
  15. 25 Jul, 2005 1 commit
  16. 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
      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.
  17. 08 Mar, 2005 1 commit
    • simonmar's avatar
      [project @ 2005-03-08 17:12:51 by simonmar] · a8a2fc9c
      simonmar authored
      Fix something that's been bugging me for a while: by default, -ddump-*
      output doesn't include uniques when it outputs internal names, but in
      most cases you need them because the output hasn't been tidied, so you
      end up doing -dppr-debug which is overkill.
      Now, -ddump-* prints uniques for internal names by default.  This
      shouldn't affect anything else.
  18. 25 Feb, 2005 1 commit
    • simonpj's avatar
      [project @ 2005-02-25 13:06:31 by simonpj] · 8e67f550
      simonpj authored
      Type signatures are no longer instantiated with skolem constants
      	Merge to STABLE
        p :: a
        q :: b
        (p,q,r) = (r,r,p)
      Here, 'a' and 'b' end up being the same, because they are both bound
      to the type for 'r', which is just a meta type variable.  So 'a' and 'b'
      can't be skolems.
      Sigh.  This commit goes back to an earlier way of doing things, by
      arranging that type signatures get instantiated with *meta* type
      variables; then at the end we must check that they have not been
      unified with types, nor with each other.
      This is a real bore.  I had to do quite a bit of related fiddling around
      to make error messages come out right.  Improved one or two.
      Also a small unrelated fix to make
      	:i (:+)
      print with parens in ghci.  Sorry this got mixed up in the same commit.
  19. 26 Nov, 2004 1 commit
    • simonmar's avatar
      [project @ 2004-11-26 16:19:45 by simonmar] · ef5b4b14
      simonmar authored
      Further integration with the new package story.  GHC now supports
      pretty much everything in the package proposal.
        - GHC now works in terms of PackageIds (<pkg>-<version>) rather than
          just package names.  You can still specify package names without
          versions on the command line, as long as the name is unambiguous.
        - GHC understands hidden/exposed modules in a package, and will refuse
          to import a hidden module.  Also, the hidden/eposed status of packages
          is taken into account.
        - I had to remove the old package syntax from ghc-pkg, backwards
          compatibility isn't really practical.
        - All the package.conf.in files have been rewritten in the new syntax,
          and contain a complete list of modules in the package.  I've set all
          the versions to 1.0 for now - please check your package(s) and fix the
          version number & other info appropriately.
        - New options:
      	-hide-package P    sets the expose flag on package P to False
      	-ignore-package P  unregisters P for this compilation
      	For comparison, -package P sets the expose flag on package P
              to True, and also causes P to be linked in eagerly.
              -package-name is no longer officially supported.  Unofficially, it's
      	a synonym for -ignore-package, which has more or less the same effect
      	as -package-name used to.
      	Note that a package may be hidden and yet still be linked into
      	the program, by virtue of being a dependency of some other package.
      	To completely remove a package from the compiler's internal database,
              use -ignore-package.
      	The compiler will complain if any two packages in the
              transitive closure of exposed packages contain the same
      	You *must* use -ignore-package P when compiling modules for
              package P, if package P (or an older version of P) is already
              registered.  The compiler will helpfully complain if you don't.
      	The fptools build system does this.
         - Note: the Cabal library won't work yet.  It still thinks GHC uses
           the old package config syntax.
      Internal changes/cleanups:
         - The ModuleName type has gone away.  Modules are now just (a
           newtype of) FastStrings, and don't contain any package information.
           All the package-related knowledge is in DynFlags, which is passed
           down to where it is needed.
         - DynFlags manipulation has been cleaned up somewhat: there are no
           global variables holding DynFlags any more, instead the DynFlags
           are passed around properly.
         - There are a few less global variables in GHC.  Lots more are
           scheduled for removal.
         - -i is now a dynamic flag, as are all the package-related flags (but
           using them in {-# OPTIONS #-} is Officially Not Recommended).
         - make -j now appears to work under fptools/libraries/.  Probably
           wouldn't take much to get it working for a whole build.
  20. 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
          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
      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).
  21. 31 Aug, 2004 1 commit
  22. 27 Aug, 2004 1 commit
  23. 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.
  24. 16 Aug, 2004 1 commit
    • simonpj's avatar
      [project @ 2004-08-16 09:53:47 by simonpj] · 4e325538
      simonpj authored
      	Add instance information to :i
       	Get rid of the DeclPool
      1.  Add instance information to :info command.  GHCi now prints out
          which instances a type or class belongs to, when you use :i
      2.  Tidy up printing of unqualified names in user output.
          Previously Outputable.PrintUnqualified was
      	type PrintUnqualified = Name -> Bool
          but it's now
      	type PrintUnqualified = ModuleName -> OccName -> Bool
          This turns out to be tidier even for Names, and it's now also usable
          when printing IfaceSyn stuff in GHCi, eliminating a grevious hack.
      3.  On the way to doing this, Simon M had the great idea that we could
          get rid of the DeclPool holding pen, which held declarations read from
          interface files but not yet type-checked.   We do this by eagerly
          populating the TypeEnv with thunks what, when poked, do the type
          checking.   This is just a logical continuation of lazy import
          mechanism we've now had for some while.
      The InstPool and RulePool still exist, but I plan to get rid of them in
      the same way.  The new scheme does mean that more rules get sucked in than
      before, because previously the TypeEnv was used to mean "this thing was needed"
      and hence to control which rules were sucked in.  But now the TypeEnv is
      populated more eagerly => more rules get sucked in.  However this problem
      will go away when I get rid of the Inst and Rule pools.
      I should have kept these changes separate, but I didn't.  Change (1)
      affects mainly
      	TcRnDriver, HscMain, CompMan, InteractiveUI
      whereas change (3) is more wide ranging.
  25. 13 Aug, 2004 1 commit
  26. 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
      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.
  27. 06 Nov, 2003 1 commit
    • simonpj's avatar
      [project @ 2003-11-06 17:09:50 by simonpj] · 1f5e5580
      simonpj authored
      	Major increment for Template Haskell
      1.  New abstract data type "Name" which appears where String used to be.
          E.g. 	data Exp = VarE Name | ...
      2.  New syntax 'x and ''T, for quoting Names.  It's rather like [| x |]
          and [t| T |] respectively, except that
      	a) it's non-monadic:  'x :: Name
      	b) you get a Name not an Exp or Type
      3.  reify is an ordinary function
      	reify :: Name -> Q Info
          New data type Info which tells what TH knows about Name
      4.  Local variables work properly.  So this works now (crashed before):
      	f x = $( [| x |] )
      5.  THSyntax is split up into three modules:
        Language.Haskell.TH		TH "clients" import this
        Language.Haskell.TH.THSyntax	data type declarations and internal stuff
        Language.Haskell.TH.THLib	Support library code (all re-exported
      				by TH), including smart constructors and
      				pretty printer
      6.  Error reporting and recovery are in (not yet well tested)
      	report :: Bool {- True <=> fatal -} -> String -> Q ()
      	recover :: Q a -> Q a -> Q a
      7.  Can find current module
      	currentModule :: Q String
      Much other cleaning up, needless to say.
  28. 30 Oct, 2003 1 commit
    • simonpj's avatar
      [project @ 2003-10-30 16:01:49 by simonpj] · 57573e7e
      simonpj authored
      This commit does a long-overdue tidy-up
      * Remove PprType (gets rid of one more bunch of hi-boot files)
      * Put pretty-printing for types in TypeRep
      * Make a specialised pretty-printer for Types, rather than
        converting to IfaceTypes and printing those
  29. 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
      * 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
      * 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
      * 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
  30. 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
      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.
  31. 28 Oct, 2002 1 commit
  32. 25 Oct, 2002 1 commit
  33. 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.
  34. 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
      * 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
        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.
      	HsPat.InPat	--> HsPat.Pat
      	HsPat.OutPat	--> HsPat.Pat
      	No 'pat' type parameter in HsExpr, HsBinds, etc
      	Constructor patterns are nicer now: they use
      	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.
  35. 29 Jul, 2002 1 commit
    • simonmar's avatar
      [project @ 2002-07-29 10:50:43 by simonmar] · 5bca7237
      simonmar authored
      Type variables created by the typechecker didn't have the correct
      NameSpace: they were in the Var namespace rather than the TyVar
      namespace, which can lead to strange warnings about quantified type
      variables being not mentioned in the type when DEBUG is on.
      	- added mkSystemNameEncoded for use when the string
      	  is already encoded (saves re-encoding the string every
      	- added mkSystemTvNameEncoded for making a type variable
      	  name, as above
      	- use mkSystemTvNameEncoded when making type variables
      	- add mkSysLocalUnencoded for the (rare) case when
      	  the string needs encoding
      	- use mkSystemTvNameEncoded rather than mkSystemName for
      	  making type variables
      	- use mkSysLocalUnencoded since the names generated here
      	  need encoding.
  36. 27 May, 2002 1 commit
  37. 15 Mar, 2002 1 commit
  38. 14 Mar, 2002 1 commit