1. 11 Aug, 2006 1 commit
  2. 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
  3. 01 Mar, 2006 1 commit
  4. 03 Feb, 2006 1 commit
  5. 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) = ... 
      	      in 
         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.
      ac10f840
  6. 27 Oct, 2005 1 commit
    • simonpj's avatar
      [project @ 2005-10-27 14:35:20 by simonpj] · 958924a2
      simonpj authored
      Add a new pragma: SPECIALISE INLINE
      
      This amounts to adding an INLINE pragma to the specialised version
      of the function.  You can add phase stuff too (SPECIALISE INLINE [2]),
      and NOINLINE instead of INLINE.
      
      The reason for doing this is to support inlining of type-directed
      recursive functions.  The main example is this:
      
        -- non-uniform array type
        data Arr e where
          ArrInt  :: !Int -> ByteArray#       -> Arr Int
          ArrPair :: !Int -> Arr e1 -> Arr e2 -> Arr (e1, e2)
      
        (!:) :: Arr e -> Int -> e
        {-# SPECIALISE INLINE (!:) :: Arr Int -> Int -> Int #-}
        {-# SPECIALISE INLINE (!:) :: Arr (a, b) -> Int -> (a, b) #-}
        ArrInt  _ ba    !: (I# i) = I# (indexIntArray# ba i)
        ArrPair _ a1 a2 !: i      = (a1 !: i, a2 !: i)
      
      If we use (!:) at a particular array type, we want to inline (:!),
      which is recursive, until all the type specialisation is done.
      
      
      On the way I did a bit of renaming and tidying of the way that
      pragmas are carried, so quite a lot of files are touched in a
      fairly trivial way.
      958924a2
  7. 10 Aug, 2005 1 commit
    • simonpj's avatar
      [project @ 2005-08-10 11:05:06 by simonpj] · e3a4d6c3
      simonpj authored
      It turned out that doing all binding dependency analysis in the typechecker
      meant that the renamer's unused-binding error messages got worse.  So now
      I've put the first dep anal back into the renamer, while the second (which
      is specific to type checking) remains in the type checker.
      
      I've also made the pretty printer sort the decls back into source order
      before printing them (except with -dppr-debug).
      
      Fixes rn041.
      e3a4d6c3
  8. 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
  9. 31 Mar, 2005 1 commit
    • simonmar's avatar
      [project @ 2005-03-31 10:16:33 by simonmar] · 853e20a3
      simonmar authored
      Tweaks to get the GHC sources through Haddock.  Doesn't quite work
      yet, because Haddock complains about the recursive modules.  Haddock
      needs to understand SOURCE imports (it can probably just ignore them
      as a first attempt).
      853e20a3
  10. 27 Jan, 2005 1 commit
    • simonpj's avatar
      [project @ 2005-01-27 10:44:00 by simonpj] · 508a505e
      simonpj authored
      --------------------------------------------
                Replace hi-boot files with hs-boot files
        	--------------------------------------------
      
      This major commit completely re-organises the way that recursive modules
      are dealt with.
      
        * It should have NO EFFECT if you do not use recursive modules
      
        * It is a BREAKING CHANGE if you do
      
      ====== Warning: .hi-file format has changed, so if you are
      ======		updating into an existing HEAD build, you'll
      ======		need to make clean and re-make
      
      
      The details:  [documentation still to be done]
      
      * Recursive loops are now broken with Foo.hs-boot (or Foo.lhs-boot),
        not Foo.hi-boot
      
      * An hs-boot files is a proper source file.  It is compiled just like
        a regular Haskell source file:
      	ghc Foo.hs		generates Foo.hi, Foo.o
      	ghc Foo.hs-boot		generates Foo.hi-boot, Foo.o-boot
      
      * hs-boot files are precisely a subset of Haskell. In particular:
      	- they have the same import, export, and scoping rules
      	- errors (such as kind errors) in hs-boot files are checked
        You do *not* need to mention the "original" name of something in
        an hs-boot file, any more than you do in any other Haskell module.
      
      * The Foo.hi-boot file generated by compiling Foo.hs-boot is a machine-
        generated interface file, in precisely the same format as Foo.hi
      
      * When compiling Foo.hs, its exports are checked for compatibility with
        Foo.hi-boot (previously generated by compiling Foo.hs-boot)
      
      * The dependency analyser (ghc -M) knows about Foo.hs-boot files, and
        generates appropriate dependencies.  For regular source files it
        generates
      	Foo.o : Foo.hs
      	Foo.o : Baz.hi		-- Foo.hs imports Baz
      	Foo.o : Bog.hi-boot	-- Foo.hs source-imports Bog
      
        For a hs-boot file it generates similar dependencies
      	Bog.o-boot : Bog.hs-boot
      	Bog.o-boot : Nib.hi	-- Bog.hs-boto imports Nib
      
      * ghc -M is also enhanced to use the compilation manager dependency
        chasing, so that
      	ghc -M Main
        will usually do the job.  No need to enumerate all the source files.
      
      * The -c flag is no longer a "compiler mode". It simply means "omit the
        link step", and synonymous with -no-link.
      508a505e
  11. 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
  12. 12 Mar, 2004 1 commit
  13. 11 Mar, 2004 1 commit
  14. 16 Dec, 2003 1 commit
    • simonpj's avatar
      [project @ 2003-12-16 16:24:55 by simonpj] · cb2be98a
      simonpj authored
      --------------------
      	Towards type splices
      	--------------------
      
      Starts the move to supporting type splices, by making
      HsExpr.HsSplice a separate type of its own, and adding
      HsSpliceTy constructor to HsType.
      cb2be98a
  15. 10 Dec, 2003 2 commits
    • simonmar's avatar
      [project @ 2003-12-10 17:25:12 by simonmar] · c7b38930
      simonmar authored
      Cleanups:
      
      - Move the collect* functions from HsSyn into HsUtils.  Check that we
        have a clean separation of utilties over HsSyn, with the generic
        versions in HsUtils, and the specific versions in RdrHsSyn, RnHsSyn
        and TcHsSyn as appropriate.
      
      - Remove the RdrBinding data type, which was really just a nested list
        with O(1) append, and use OrdList instead.  This makes it much clearer
        that there's nothing strange going on.
      
      - Various other minor cleanups.
      c7b38930
    • 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
  16. 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
  17. 24 Sep, 2003 1 commit
  18. 21 Feb, 2003 1 commit
    • simonpj's avatar
      [project @ 2003-02-21 13:27:53 by simonpj] · 84ed91ab
      simonpj authored
      -------------------------------------
      	Improve the "unused binding" warnings
      	-------------------------------------
      
      We've had a succession of hacks for reporting warnings for
      unused bindings.  Consider
      
      	module M( f ) where
      
       	f x = x
      
      	g x = g x + h x
      	h x = x
      
      Here, g mentions itself and h, but is not itself mentioned. So
      really both g and h are dead code.  We've been getting this wrong
      for ages, and every hack so far has failed on some simple programs.
      
      This commit does a much better job.  The renamer applied to a bunch
      of bindings returns a NameSet.DefUses, which is a dependency-ordered
      lists of def/use pairs.  It's documented in NameSet.
      Given this, we can work out precisely what is not used, in a nice
      tidy way.
      
      It's less convenient in the case of type and class declarations, because
      the strongly-connected-component analysis can span module boundaries.
      So things are pretty much as they were for these.
      
      
      As usual, there was a lot of chuffing around tidying things up.
      I havn't tested it at all thoroughly yet.
      
      Various unrelated import-decl-pruning has been done too.
      84ed91ab
  19. 25 Oct, 2002 1 commit
  20. 23 Oct, 2002 1 commit
    • simonpj's avatar
      [project @ 2002-10-23 14:30:00 by simonpj] · 203a687f
      simonpj authored
      ------------------------------------------------
      	Allow implicit-parameter bindings anywhere that
      		a normal binding group is allowed.
      	------------------------------------------------
      
      That is, you can have implicit parameters
      
      	* in a let binding
      	* in a where clause (but then you can't have non-implicit
      	  ones as well)
      	* in a let group in a list comprehension or monad do-notation
      
      The implementation is simple: just add IPBinds to the allowable forms of HsBinds,
      and remove the HsWith expression form altogether.   (It now comes in via the
      HsLet form.)
      
      It'a a nice generalisation really.  Needs a bit of documentation, which I'll do next.
      203a687f
  21. 09 Oct, 2002 1 commit
    • simonpj's avatar
      [project @ 2002-10-09 15:03:48 by simonpj] · 8c1b6bd7
      simonpj authored
      -----------------------------------
      	Lots more Template Haskell stuff
      	-----------------------------------
      
      At last!  Top-level declaration splices work!
      Syntax is
      
      	$(f x)
      
      not "splice (f x)" as in the paper.
      
      Lots jiggling around, particularly with the top-level plumbining.
      Note the new data type HsDecls.HsGroup.
      8c1b6bd7
  22. 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
  23. 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
  24. 16 Jul, 2002 1 commit
  25. 29 Apr, 2002 1 commit
    • simonmar's avatar
      [project @ 2002-04-29 14:03:38 by simonmar] · b085ee40
      simonmar authored
      FastString cleanup, stage 1.
      
      The FastString type is no longer a mixture of hashed strings and
      literal strings, it contains hashed strings only with O(1) comparison
      (except for UnicodeStr, but that will also go away in due course).  To
      create a literal instance of FastString, use FSLIT("..").
      
      By far the most common use of the old literal version of FastString
      was in the pattern
      
      	  ptext SLIT("...")
      
      this combination still works, although it doesn't go via FastString
      any more.  The next stage will be to remove the need to use this
      special combination at all, using a RULE.
      
      To convert a FastString into an SDoc, now use 'ftext' instead of
      'ptext'.
      
      I've also removed all the FAST_STRING related macros from HsVersions.h
      except for SLIT and FSLIT, just use the relevant functions from
      FastString instead.
      b085ee40
  26. 14 Mar, 2002 1 commit
  27. 29 Jan, 2002 1 commit
    • simonpj's avatar
      [project @ 2002-01-29 09:58:14 by simonpj] · f2054812
      simonpj authored
      ------------
      	Rule phasing
      	------------
      
      This commit adds a little more control to when rules are enabled.
      
        {-# RULES
             "foo" [2] forall ...
             "baz" [~2] forall ...
        #-}
      
      Rule "foo" is active in phase 2 and later.  The new thing is that the
      "~2" means that Rule "baz" is active in phase 3 and earlier.
      (Remember tha phases decrease towards zero.)
      
      All the machinery was there to implement this, it just needed the syntax.
      
      
      Why do this?  Peter Gammie (at UNSW) found that rules weren't firing
      because of bindings of the form
      
      	M.f = f
      	f = ....
      
      where the rules where on the M.f binding.  It turned out that an old
      hack (which have for some time elicited the harmless "shortMeOut" debug
      warnings) prevented this trivial construction from being correctly
      simplified.  The hack in turn derived from a trick in the way the
      foldr/build rule was implemented....and that hack is no longer necessary
      now we can switch rules *off* as well as *on*.
      
      
      There are consequential changes in the Prelude foldr/build RULE stuff.
      It's a clean-up.... Instead of strange definitions like
      	map = mapList
      which we had before, we have an ordinary recursive defn of map, together
      with rules to convert first to foldr/build form, and then (if nothing
      happens) back again.
      
      There's a fairly long comment about the general plan of attack in
      PrelBase, near the defn of map.
      f2054812
  28. 06 Dec, 2001 1 commit
  29. 26 Sep, 2001 1 commit
    • simonpj's avatar
      [project @ 2001-09-26 15:12:33 by simonpj] · e0d750be
      simonpj authored
      ------------------
      		Simon's big commit
      		------------------
      
      This commit, which I don't think I can sensibly do piecemeal, consists
      of the things I've been doing recently, mainly directed at making
      Manuel, George, and Marcin happier with RULES.
      
      
      Reogranise the simplifier
      ~~~~~~~~~~~~~~~~~~~~~~~~~
      1. The simplifier's environment is now an explicit parameter.  This
      makes it a bit easier to figure out where it is going.
      
      2. Constructor arguments can now be arbitrary expressions, except
      when the application is the RHS of a let(rec).  This makes it much
      easier to match rules like
      
      	RULES
      	    "foo"  f (h x, g y) = f' x y
      
      In the simplifier, it's Simplify.mkAtomicArgs that ANF-ises a
      constructor application where necessary.  In the occurrence analyser,
      there's a new piece of context info (OccEncl) to say whether a
      constructor app is in a place where it should be in ANF.  (Unless
      it knows this it'll give occurrence info which will inline the
      argument back into the constructor app.)
      
      3. I'm experimenting with doing the "float-past big lambda" transformation
      in the full laziness pass, rather than mixed in with the simplifier (was
      tryRhsTyLam).
      
      4.  Arrange that
      	case (coerce (S,T) (x,y)) of ...
      will simplify.  Previous it didn't.
      A local change to CoreUtils.exprIsConApp_maybe.
      
      5. Do a better job in CoreUtils.exprEtaExpandArity when there's an
      error function in one branch.
      
      
      Phase numbers, RULES, and INLINE pragmas
      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      1.  Phase numbers decrease from N towards zero (instead of increasing).
      This makes it easier to add new earlier phases, which is what users want
      to do.
      
      2.  RULES get their own phase number, N, and are disabled in phases before N.
      
      e.g. 	{-# RULES "foo" [2] forall x y.  f (x,y) = f' x y #-}
      
      Note the [2], which says "only active in phase 2 and later".
      
      3.  INLINE and NOINLINE pragmas have a phase number to.  This is now treated
      in just the same way as the phase number on RULE; that is, the Id is not inlined
      in phases earlier than N.  In phase N and later the Id *may* be inlined, and
      here is where INLINE and NOINLINE differ: INLNE makes the RHS look small, so
      as soon as it *may* be inlined it probably *will* be inlined.
      
      The syntax of the phase number on an INLINE/NOINLINE pragma has changed to be
      like the RULES case (i.e. in square brackets).  This should also make sure
      you examine all such phase numbers; many will need to change now the numbering
      is reversed.
      
      Inlining Ids is no longer affected at all by whether the Id appears on the
      LHS of a rule.  Now it's up to the programmer to put a suitable INLINE/NOINLINE
      pragma to stop it being inlined too early.
      
      
      Implementation notes:
      
      *  A new data type, BasicTypes.Activation says when a rule or inline pragma
      is active.   Functions isAlwaysActive, isNeverActive, isActive, do the
      obvious thing (all in BasicTypes).
      
      * Slight change in the SimplifierSwitch data type, which led to a lot of
      simplifier-specific code moving from CmdLineOpts to SimplMonad; a Good Thing.
      
      * The InlinePragma in the IdInfo of an Id is now simply an Activation saying
      when the Id can be inlined.  (It used to be a rather bizarre pair of a
      Bool and a (Maybe Phase), so this is much much easier to understand.)
      
      * The simplifier has a "mode" environment switch, replacing the old
      black list.  Unfortunately the data type decl has to be in
      CmdLineOpts, because it's an argument to the CoreDoSimplify switch
      
          data SimplifierMode = SimplGently | SimplPhase Int
      
      Here "gently" means "no rules, no inlining".   All the crucial
      inlining decisions are now collected together in SimplMonad
      (preInlineUnconditionally, postInlineUnconditionally, activeInline,
      activeRule).
      
      
      Specialisation
      ~~~~~~~~~~~~~~
      1.  Only dictionary *functions* are made INLINE, not dictionaries that
      have no parameters.  (This inline-dictionary-function thing is Marcin's
      idea and I'm still not sure whether it's a good idea.  But it's definitely
      a Bad Idea when there are no arguments.)
      
      2.  Be prepared to specialise an INLINE function: an easy fix in
      Specialise.lhs
      
      But there is still a problem, which is that the INLINE wins
      at the call site, so we don't use the specialised version anyway.
      I'm still unsure whether it makes sense to SPECIALISE something
      you want to INLINE.
      
      
      
      
      
      Random smaller things
      ~~~~~~~~~~~~~~~~~~~~~~
      
      * builtinRules (there was only one, but may be more) in PrelRules are now
        incorporated.   They were being ignored before...
      
      * OrdList.foldOL -->  OrdList.foldrOL, OrdList.foldlOL
      
      * Some tidying up of the tidyOpenTyVar, tidyTyVar functions.  I've
        forgotten exactly what!
      e0d750be
  30. 16 Aug, 2001 1 commit
    • simonmar's avatar
      [project @ 2001-08-16 10:25:21 by simonmar] · a035c70f
      simonmar authored
      Prettier output for GHCi's :info
      
        - put parenthesis around operators in type signatures
          (both IfaceSig and ClassOpSig)
      
        - don't use the cryptic '= ::' notation for indicating that a
          class op has a default method, instead put the information in a
          comment after the type.
      a035c70f
  31. 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
  32. 01 May, 2001 1 commit
  33. 14 Apr, 2001 1 commit
  34. 26 Feb, 2001 1 commit
    • simonmar's avatar
      [project @ 2001-02-26 15:06:57 by simonmar] · 1c62b517
      simonmar authored
      Implement do-style bindings on the GHCi command line.
      
      The syntax for a command-line is exactly that of a do statement, with
      the following meanings:
      
        - `pat <- expr'
          performs expr, and binds each of the variables in pat.
      
        - `let pat = expr; ...'
          binds each of the variables in pat, doesn't do any evaluation
      
        - `expr'
          behaves as `it <- expr' if expr is IO-typed, or `let it = expr'
          followed by `print it' otherwise.
      1c62b517
  35. 20 Dec, 2000 1 commit
  36. 24 Nov, 2000 1 commit
    • simonpj's avatar
      [project @ 2000-11-24 17:02:01 by simonpj] · 83eef621
      simonpj authored
      1. Make the new version machinery work.
         I think it does now!
      
      2. Consequence of (1): Move the generation of
         default method names to one place (namely
         in RdrHsSyn.mkClassOpSigDM
      
      3. Major clean up on HsDecls.TyClDecl
         These big constructors should have been records
         ages ago, and they are now.  At last.
      83eef621
  37. 10 Nov, 2000 1 commit
    • simonpj's avatar
      [project @ 2000-11-10 15:12:50 by simonpj] · f23ba2b2
      simonpj authored
      1.	Outputable.PprStyle now carries a bit more information
      	In particular, the printing style tells whether to print
      	a name in unqualified form.  This used to be embedded in
      	a Name, but since Names now outlive a single compilation unit,
      	that's no longer appropriate.
      
      	So now the print-unqualified predicate is passed in the printing
      	style, not embedded in the Name.
      
         2.	I tidied up HscMain a little.  Many of the showPass messages
      	have migraged into the repective pass drivers
      f23ba2b2
  38. 23 Oct, 2000 1 commit
  39. 12 Oct, 2000 1 commit