1. 31 Jul, 2008 1 commit
  2. 29 Mar, 2008 1 commit
  3. 28 Feb, 2008 1 commit
  4. 03 Feb, 2008 1 commit
  5. 17 Jan, 2008 1 commit
  6. 20 Dec, 2007 1 commit
    • simonpj@microsoft.com's avatar
      Implement generalised list comprehensions · 67cb4091
      simonpj@microsoft.com authored
        This patch implements generalised list comprehensions, as described in 
        the paper "Comprehensive comprehensions" (Peyton Jones & Wadler, Haskell
        Workshop 2007).  If you don't use the new comprehensions, nothing
        should change.
        
        The syntax is not exactly as in the paper; see the user manual entry 
        for details.
        
        You need an accompanying patch to the base library for this stuff 
        to work.
        
        The patch is the work of Max Bolingbroke [batterseapower@hotmail.com], 
        with some advice from Simon PJ.
        
        The related GHC Wiki page is 
          http://hackage.haskell.org/trac/ghc/wiki/SQLLikeComprehensions 
      67cb4091
  7. 05 Dec, 2007 1 commit
  8. 04 Sep, 2007 1 commit
  9. 03 Sep, 2007 1 commit
  10. 01 Sep, 2007 1 commit
  11. 10 May, 2007 1 commit
  12. 04 May, 2007 1 commit
    • simonpj@microsoft.com's avatar
      Make -frewrite-rules into a dynamic flag; off for -O0 · 5943ce90
      simonpj@microsoft.com authored
      Argubly rewrite rules should not fire with -O0, and it turns
      out that when compiling GHC.Base with -O0 we get a crash if
      the rewrite rules do fire (see Note [Scoping for Builtin rules]
      in PrelRules).
      
      So unless someone yells, rewrite rules are off with -O0.
      
      The new (now dynamic) flag is 
          -frewrite rules (with -fno-rewrite-rules to disable)
      
      The old (static) flag -frules-off is gone.
      5943ce90
  13. 02 Apr, 2007 1 commit
  14. 11 Oct, 2006 1 commit
    • 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
      49c98d14
  15. 04 Aug, 2006 1 commit
  16. 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
  17. 02 Feb, 2006 1 commit
  18. 19 Jul, 2005 1 commit
    • simonpj's avatar
      [project @ 2005-07-19 16:44:50 by simonpj] · a7ecdf96
      simonpj authored
      WARNING: this is a big commit.  You might want 
      	to wait a few days before updating, in case I've 
      	broken something.
      
      	However, if any of the changes are what you wanted,
      	please check it out and test!
      
      This commit does three main things:
      
      1. A re-organisation of the way that GHC handles bindings in HsSyn.
         This has been a bit of a mess for quite a while.  The key new
         types are
      
      	-- Bindings for a let or where clause
      	data HsLocalBinds id
      	  = HsValBinds (HsValBinds id)
      	  | HsIPBinds  (HsIPBinds id)
      	  | EmptyLocalBinds
      
      	-- Value bindings (not implicit parameters)
      	data HsValBinds id
      	  = ValBindsIn  -- Before typechecking
      		(LHsBinds id) [LSig id]	-- Not dependency analysed
      					-- Recursive by default
      
      	  | ValBindsOut	-- After typechecking
      		[(RecFlag, LHsBinds id)]-- Dependency analysed
      
      2. Implement Mark Jones's idea of increasing polymoprhism
         by using type signatures to cut the strongly-connected components
         of a recursive group.  As a consequence, GHC no longer insists
         on the contexts of the type signatures of a recursive group
         being identical.
      
         This drove a significant change: the renamer no longer does dependency
         analysis.  Instead, it attaches a free-variable set to each binding,
         so that the type checker can do the dep anal.  Reason: the typechecker
         needs to do *two* analyses:
      	one to find the true mutually-recursive groups
      		(which we need so we can build the right CoreSyn)
      	one to find the groups in which to typecheck, taking
      		account of type signatures
      
      3. Implement non-ground SPECIALISE pragmas, as promised, and as
         requested by Remi and Ross.  Certainly, this should fix the 
         current problem with GHC, namely that if you have
      	g :: Eq a => a -> b -> b
         then you can now specialise thus
      	SPECIALISE g :: Int -> b -> b
          (This didn't use to work.)
      
         However, it goes further than that.  For example:
      	f :: (Eq a, Ix b) => a -> b -> b
         then you can make a partial specialisation
      	SPECIALISE f :: (Eq a) => a -> Int -> Int
      
          In principle, you can specialise f to *any* type that is
          "less polymorphic" (in the sense of subsumption) than f's 
          actual type.  Such as
      	SPECIALISE f :: Eq a => [a] -> Int -> Int
          But I haven't tested that.
      
          I implemented this by doing the specialisation in the typechecker
          and desugarer, rather than leaving around the strange SpecPragmaIds,
          for the specialiser to find.  Indeed, SpecPragmaIds have vanished 
          altogether (hooray).
      
          Pragmas in general are handled more tidily.  There's a new
          data type HsBinds.Prag, which lives in an AbsBinds, and carries
          pragma info from the typechecker to the desugarer.
      
      
      Smaller things
      
      - The loop in the renamer goes via RnExpr, instead of RnSource.
        (That makes it more like the type checker.)
      
      - I fixed the thing that was causing 'check_tc' warnings to be 
        emitted.
      a7ecdf96
  19. 04 Apr, 2005 1 commit
    • simonpj's avatar
      [project @ 2005-04-04 11:55:11 by simonpj] · d551dbfe
      simonpj authored
      This commit combines three overlapping things:
      
      1.  Make rebindable syntax work for do-notation. The idea
          here is that, in particular, (>>=) can have a type that
          has class constraints on its argument types, e.g.
             (>>=) :: (Foo m, Baz a) => m a -> (a -> m b) -> m b
          The consequence is that a BindStmt and ExprStmt must have
          individual evidence attached -- previously it was one
          batch of evidence for the entire Do
          
          Sadly, we can't do this for MDo, because we use bind at
          a polymorphic type (to tie the knot), so we still use one
          blob of evidence (now in the HsStmtContext) for MDo.
          
          For arrow syntax, the evidence is in the HsCmd.
          
          For list comprehensions, it's all built-in anyway.
          
          So the evidence on a BindStmt is only used for ordinary
          do-notation.
      
      2.  Tidy up HsSyn.  In particular:
      
      	- Eliminate a few "Out" forms, which we can manage
      	without (e.g. 
      
      	- It ought to be the case that the type checker only
      	decorates the syntax tree, but doesn't change one
      	construct into another.  That wasn't true for NPat,
      	LitPat, NPlusKPat, so I've fixed that.
      
      	- Eliminate ResultStmts from Stmt.  They always had
      	to be the last Stmt, which led to awkward pattern
      	matching in some places; and the benefits didn't seem
      	to outweigh the costs.  Now each construct that uses
      	[Stmt] has a result expression too (e.g. GRHS).
      
      
      3.  Make 'deriving( Ix )' generate a binding for unsafeIndex,
          rather than for index.  This is loads more efficient.
      
          (This item only affects TcGenDeriv, but some of point (2)
          also affects TcGenDeriv, so it has to be in one commit.)
      d551dbfe
  20. 18 Mar, 2005 1 commit
    • simonmar's avatar
      [project @ 2005-03-18 13:37:27 by simonmar] · d1c1b7d0
      simonmar authored
      Flags cleanup.
      
      Basically the purpose of this commit is to move more of the compiler's
      global state into DynFlags, which is moving in the direction we need
      to go for the GHC API which can have multiple active sessions
      supported by a single GHC instance.
      
      Before:
      
      $ grep 'global_var' */*hs | wc -l
           78
      
      After:
      
      $ grep 'global_var' */*hs | wc -l
           27
      
      Well, it's an improvement.  Most of what's left won't really affect
      our ability to host multiple sessions.
      
      Lots of static flags have become dynamic flags (yay!).  Notably lots
      of flags that we used to think of as "driver" flags, like -I and -L,
      are now dynamic.  The most notable static flags left behind are the
      "way" flags, eg. -prof.  It would be nice to fix this, but it isn't
      urgent.
      
      On the way, lots of cleanup has happened.  Everything related to
      static and dynamic flags lives in StaticFlags and DynFlags
      respectively, and they share a common command-line parser library in
      CmdLineParser.  The flags related to modes (--makde, --interactive
      etc.) are now private to the front end: in fact private to Main
      itself, for now.
      d1c1b7d0
  21. 03 Mar, 2005 1 commit
    • chak's avatar
      [project @ 2005-03-03 11:48:02 by chak] · 706ebc79
      chak authored
      Merge to STABLE
      
      Fixed two bugs:
      * #1035575 from SourceForge (by adding smart constructors for source tuple
        construction at value and type level)
      * Parallel array comprehensions were handled wrongly
        - The singleton expression-pattern pair `()'-`[:():]' is the neutral element
          for cross products (comma notation in comprehensions), but not for
          parallel comprehensions.
        - Now groups of parallel statements are handled separately (which is more
          like the vanilla list comprehension case).
        - The code is too general in that it correctly handles cross-products of
          groups of parallel qualifiers.  As this is correctly handled in the
          list and the array comprehension case, the syntax may be generalised to
          allow arbitrary nesting of cross-products and parallel qualifiers.
      706ebc79
  22. 22 Dec, 2004 1 commit
    • simonpj's avatar
      [project @ 2004-12-22 12:06:13 by simonpj] · d7c402a3
      simonpj authored
      ----------------------------------------
           New Core invariant: keep case alternatives in sorted order
      	----------------------------------------
      
      We now keep the alternatives of a Case in the Core language in sorted
      order.  Sorted, that is,
      	by constructor tag	for DataAlt
      	by literal		for LitAlt
      
      The main reason is that it makes matching and equality testing more robust.
      But in fact some lines of code vanished from SimplUtils.mkAlts.
      
      
      WARNING: no change to interface file formats, but you'll need to recompile
      your libraries so that they generate interface files that respect the
      invariant.
      d7c402a3
  23. 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
  24. 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
  25. 10 Dec, 2003 1 commit
    • simonmar's avatar
      [project @ 2003-12-10 14:15:16 by simonmar] · 55042138
      simonmar authored
      Add accurate source location annotations to HsSyn
      -------------------------------------------------
      
      Every syntactic entity in HsSyn is now annotated with a SrcSpan, which
      details the exact beginning and end points of that entity in the
      original source file.  All honest compilers should do this, and it was
      about time GHC did the right thing.
      
      The most obvious benefit is that we now have much more accurate error
      messages; when running GHC inside emacs for example, the cursor will
      jump to the exact location of an error, not just a line somewhere
      nearby.  We haven't put a huge amount of effort into making sure all
      the error messages are accurate yet, so there could be some tweaking
      still needed, although the majority of messages I've seen have been
      spot-on.
      
      Error messages now contain a column number in addition to the line
      number, eg.
      
         read001.hs:25:10: Variable not in scope: `+#'
      
      To get the full text span info, use the new option -ferror-spans.  eg.
      
         read001.hs:25:10-11: Variable not in scope: `+#'
      
      I'm not sure whether we should do this by default.  Emacs won't
      understand the new error format, for one thing.
      
      In a more elaborate editor setting (eg. Visual Studio), we can arrange
      to actually highlight the subexpression containing an error.  Eventually
      this information will be used so we can find elements in the abstract
      syntax corresponding to text locations, for performing high-level editor
      functions (eg. "tell me the type of this expression I just highlighted").
      
      Performance of the compiler doesn't seem to be adversely affected.
      Parsing is still quicker than in 6.0.1, for example.
      
      Implementation:
      
      This was an excrutiatingly painful change to make: both Simon P.J. and
      myself have been working on it for the last three weeks or so.  The
      basic changes are:
      
       - a new datatype SrcSpan, which represents a beginning and end position
         in a source file.
      
       - To reduce the pain as much as possible, we also defined:
      
            data Located e = L SrcSpan e
      
       - Every datatype in HsSyn has an equivalent Located version.  eg.
      
            type LHsExpr id = Located (HsExpr id)
      
         and pretty much everywhere we used to use HsExpr we now use
         LHsExpr.  Believe me, we thought about this long and hard, and
         all the other options were worse :-)
      
      
      Additional changes/cleanups we made at the same time:
      
        - The abstract syntax for bindings is now less arcane.  MonoBinds
          and HsBinds with their built-in list constructors have gone away,
          replaced by HsBindGroup and HsBind (see HsSyn/HsBinds.lhs).
      
        - The various HsSyn type synonyms have now gone away (eg. RdrNameHsExpr,
          RenamedHsExpr, and TypecheckedHsExpr are now HsExpr RdrName,
          HsExpr Name, and HsExpr Id respectively).
      
        - Utilities over HsSyn are now collected in a new module HsUtils.
          More stuff still needs to be moved in here.
      
        - MachChar now has a real Char instead of an Int.  All GHC versions that
          can compile GHC now support 32-bit Chars, so this was a simplification.
      55042138
  26. 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
  27. 23 Sep, 2003 1 commit
    • simonmar's avatar
      [project @ 2003-09-23 14:32:57 by simonmar] · abbc5a0b
      simonmar authored
      - Convert many of the optimisation options into dynamic options (that is,
        they can be mentioned in {-# OPTIONS #-} pragmas).
      
      - Add a new way to specify constructor-field unboxing on a selective
        basis.  To tell the compiler to unbox a constructor field, do this:
      
            data T = T !!Int
      
        and GHC will store that field unboxed if possible.  If it isn't possible
        (say, because the field has a sum type) then the annotation is ignored.
      
        The -funbox-strict-fields flag is now a dynamic flag, and has the same
        effect as replacing all the '!' annotations with '!!'.
      abbc5a0b
  28. 25 Jun, 2003 1 commit
  29. 24 Jun, 2003 1 commit
    • simonpj's avatar
      [project @ 2003-06-24 07:58:18 by simonpj] · 16e4ce4c
      simonpj authored
      ----------------------------------------------
      	Add support for Ross Paterson's arrow notation
      	----------------------------------------------
      
      Ross Paterson's ICFP'01 paper described syntax to support John Hughes's
      "arrows", rather as do-notation supports monads.  Except that do-notation is
      relatively modest -- you can write monads by hand without much trouble --
      whereas arrow-notation is more-or-less essential for writing arrow programs.
      It desugars to a massive pile of tuple construction and selection!
      
      For some time, Ross has had a pre-processor for arrow notation, but the
      resulting type error messages (reported in terms of the desugared code)
      are impenetrable.  This commit integrates the syntax into GHC.  The
      type error messages almost certainly still require tuning, but they should
      be better than with the pre-processor.
      
      Main syntactic changes (enabled with -farrows)
      
         exp ::= ... | proc pat -> cmd
      
         cmd ::= exp1 -<  exp2   |  exp1 >-  exp2
      	|  exp1 -<< exp2   |  exp1 >>- exp2
      	| \ pat1 .. patn -> cmd
      	| let decls in cmd
      	| if exp then cmd1 else cmd2
      	| do { cstmt1 .. cstmtn ; cmd }
      	| (| exp |) cmd1 .. cmdn
      	| cmd1 qop cmd2
      	| case exp of { calts }
      
         cstmt :: = let decls
      	 |   pat <- cmd
      	 |   rec { cstmt1 .. cstmtn }
      	 |   cmd
      
      New keywords and symbols:
      	proc rec
      	-<   >-   -<<   >>-
      	(|  |)
      
      The do-notation in cmds was not described in Ross's ICFP'01 paper; instead
      it's in his chapter in The Fun of Programming (Plagrave 2003).
      
      The four arrow-tail forms (-<) etc cover
        (a) which order the pices come in (-<  vs  >-), and
        (b) whether the locally bound variables can be used in the
      		arrow part (-<  vs  -<<) .
      In previous presentations, the higher-order-ness (b) was inferred,
      but it makes a big difference to the typing required so it seems more
      consistent to be explicit.
      
      The 'rec' form is also available in do-notation:
        * you can use 'rec' in an ordinary do, with the obvious meaning
        * using 'mdo' just says "infer the minimal recs"
      
      
      Still to do
      ~~~~~~~~~~~
      Top priority is the user manual.
      
      The implementation still lacks an implementation of
      the case form of cmd.
      
      
      Implementation notes
      ~~~~~~~~~~~~~~~~~~~~
      Cmds are parsed, and indeed renamed, as expressions.  The type checker
      distinguishes the two.
      16e4ce4c
  30. 02 Jun, 2003 2 commits
    • simonpj's avatar
      [project @ 2003-06-02 14:26:54 by simonpj] · eda83294
      simonpj authored
      Wibbles to nested tuples
      eda83294
    • simonpj's avatar
      [project @ 2003-06-02 13:28:08 by simonpj] · 663a01b2
      simonpj authored
      -------------------------------------
            Fix the big-tuple-from-desugaring problem
      	-------------------------------------
      
      The desugarer generates a tuple from
      	- mutually recursive bindings
      	- pattern bindings
      
      If either bind a lot of variables, GHC can generate a big
      tuple that isn't in the library, with subsequent disaster.
      
      This commit fixes the problem, by using nested tuples.  It
      does *not* fix the problem with big tuples written by the
      user. And there's still a potential desugarer problem with
      parallel list comprehensions that bind a lot of variables
      (and parallel array comprehensions) -- but I expect they are
      much much rarer.
      
      The fix isn't fully tested yet -- I'll try to do that today.
      663a01b2
  31. 19 Feb, 2003 1 commit
  32. 27 Sep, 2002 1 commit
    • simonpj's avatar
      [project @ 2002-09-27 08:20:43 by simonpj] · dbc254c3
      simonpj authored
      --------------------------------
              Implement recursive do-notation
      	--------------------------------
      
      This commit adds recursive do-notation, which Hugs has had for some time.
      
      	mdo { x <- foo y ;
      	      y <- baz x ;
      	      return (y,x) }
      
      turns into
      
      	do { (x,y) <- mfix (\~(x,y) -> do { x <- foo y;
      					    y <- baz x }) ;
      	     return (y,x) }
      
      This is all based on work by Levent Erkok and John Lanuchbury.
      
      The really tricky bit is in the renamer (RnExpr.rnMDoStmts) where
      we break things up into minimal segments.  The rest is easy, including
      the type checker.
      
      Levent laid the groundwork, and Simon finished it off. Needless to say,
      I couldn't resist tidying up other stuff, so there's no guaranteed I
      have not broken something.
      dbc254c3
  33. 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
  34. 13 Feb, 2002 1 commit
  35. 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
  36. 12 Jul, 2001 1 commit
    • simonpj's avatar
      [project @ 2001-07-12 16:21:22 by simonpj] · ab46fd8e
      simonpj authored
      --------------------------------------------
      	Fix another bug in the squash-newtypes story.
      	--------------------------------------------
      
      [This one was spotted by Marcin, and is now enshrined in test tc130.]
      
      The desugarer straddles the boundary between the type checker and
      Core, so it sometimes needs to look through newtypes/implicit parameters
      and sometimes not.  This is really a bit painful, but I can't think of
      a better way to do it.
      
      The only simple way to fix things was to pass a bit more type
      information in the HsExpr type, from the type checker to the desugarer.
      That led to the non-local changes you can see.
      
      On the way I fixed one other thing.  In various HsSyn constructors
      there is a Type that is bogus (bottom) before the type checker, and
      filled in with a real type by the type checker.  In one place it was
      a (Maybe Type) which was Nothing before, and (Just ty) afterwards.
      I've defined a type synonym HsTypes.PostTcType for this, and a named
      bottom value HsTypes.placeHolderType to use when you want the bottom
      value.
      ab46fd8e
  37. 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
  38. 11 Jun, 2001 1 commit
    • simonpj's avatar
      [project @ 2001-06-11 12:24:51 by simonpj] · 2c6d73e2
      simonpj authored
      --------------------------------------
      	Tidy up and improve "pattern contexts"
      	--------------------------------------
      
      In various places (renamer, typechecker, desugarer) we need to know
      what the context of a pattern match is (case expression, function defn,
      let binding, etc).  This commit tidies up the story quite a bit.  I
      think it represents a net decrease in code, and certainly it improves the
      error messages from:
      
      	f x x = 3
      
      Prevsiously we got a message like "Conflicting bindings for x in a pattern match",
      but not it says "..in a defn of function f".
      
      WARNING: the tidy up had a more global effect than I originally expected,
      so it's possible that some other error messages look a bit peculiar.  They
      should be easy to fix, but tell us!
      2c6d73e2
  39. 08 May, 2001 1 commit
    • simonpj's avatar
      [project @ 2001-05-08 14:44:37 by simonpj] · 7c72bad5
      simonpj authored
      ****	MERGE WITH 5.00 BRANCH     ********
      
      	--------------------------------------
      	Make parallel list comprehensions work
      	--------------------------------------
      
      There were two bugs
      
      1.  The desugaring in DsListComp was generating code that failed Lint.
          I've restructured it quite a lot.
      
      2.  More seriously, in a ParStmt, the last 'stmt' may be a guard;
          but previously both guards and the result of a list comprehension
          were encoded as an ExprStmt (see HsExpr.Stmt), using the fact that
          the stmt was last in the list to make the difference between a guard
          and a result.  But in parallel list comp this isn't right:
      
      	[ e | x <- xs, guard | y <- ys ]
      
          Here 'guard' is last in its list, but isn't an overall result.
      
          The sensible fix is to properly distinguish
      	"here's the answer" 			 (ResultStmt)
      	"here's a guard or an imperative action" (ExprStmt)
      
          The fix is rather easy, but touched quite a lot of files.  On the
          way I tidied up the parser a little.
      7c72bad5