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  1. 29 Apr, 2005 1 commit
  2. 28 Apr, 2005 1 commit
    • simonpj's avatar
      [project @ 2005-04-28 10:09:41 by simonpj] · dd313897
      simonpj authored
      This big commit does several things at once (aeroplane hacking)
      which change the format of interface files.  
      	So you'll need to recompile your libraries!
      1. The "stupid theta" of a newtype declaration
      Retain the "stupid theta" in a newtype declaration.
      For some reason this was being discarded, and putting it
      back in meant changing TyCon and IfaceSyn slightly.
      2. Overlap flags travel with the instance
      Arrange that the ability to support overlap and incoherence
      is a property of the *instance declaration* rather than the
      module that imports the instance decl.  This allows a library
      writer to define overlapping instance decls without the
      library client having to know.  
      The implementation is that in an Instance we store the
      overlap flag, and preseve that across interface files
      3. Nuke the "instnce pool" and "rule pool"
      A major tidy-up and simplification of the way that instances
      and rules are sucked in from interface files.  Up till now
      an instance decl has been held in a "pool" until its "gates" 
      (a set of Names) are in play, when the instance is typechecked
      and added to the InstEnv in the ExternalPackageState.  
      This is complicated and error-prone; it's easy to suck in 
      too few (and miss an instance) or too many (and thereby be
      forced to suck in its type constructors, etc).
      Now, as we load an instance from an interface files, we 
      put it straight in the InstEnv... but the Instance we put in
      the InstEnv has some Names (the "rough-match" names) that 
      can be used on lookup to say "this Instance can't match".
      The detailed dfun is only read lazily, and the rough-match
      thing meansn it is'nt poked on until it has a chance of
      being needed.
      This simply continues the successful idea for Ids, whereby
      they are loaded straightaway into the TypeEnv, but their
      TyThing is a lazy thunk, not poked on until the thing is looked
      Just the same idea applies to Rules.
      On the way, I made CoreRule and Instance into full-blown records
      with lots of info, with the same kind of key status as TyCon or 
      DataCon or Class.  And got rid of IdCoreRule altogether.   
      It's all much more solid and uniform, but it meant touching
      a *lot* of modules.
      4. Allow instance decls in hs-boot files
      Allowing instance decls in hs-boot files is jolly useful, becuase
      in a big mutually-recursive bunch of data types, you want to give
      the instances with the data type declarations.  To achieve this
      * The hs-boot file makes a provisional name for the dict-fun, something
        like $fx9.
      * When checking the "mother module", we check that the instance
        declarations line up (by type) and generate bindings for the 
        boot dfuns, such as
      	$fx9 = $f2
        where $f2 is the dfun generated by the mother module
      * In doing this I decided that it's cleaner to have DFunIds get their
        final External Name at birth.  To do that they need a stable OccName,
        so I have an integer-valued dfun-name-supply in the TcM monad.
        That keeps it simple.
      This feature is hardly tested yet.
      5. Tidy up tidying, and Iface file generation
      main/TidyPgm now has two entry points:
        simpleTidyPgm is for hi-boot files, when typechecking only
        (not yet implemented), and potentially when compiling without -O.
        It ignores the bindings, and generates a nice small TypeEnv.
        optTidyPgm is the normal case: compiling with -O.  It generates a
        TypeEnv rich in IdInfo
      MkIface.mkIface now only generates a ModIface.  A separate
      procedure, MkIface.writeIfaceFile, writes the file out to disk.
  3. 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).
  4. 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.
      $ grep 'global_var' */*hs | wc -l
      $ grep 'global_var' */*hs | wc -l
      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
      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.
  5. 07 Mar, 2005 1 commit
    • simonpj's avatar
      [project @ 2005-03-07 16:46:08 by simonpj] · 36d22a1c
      simonpj authored
             Fix a long-standing indirection-zapping bug
      	Merge to STABLE
      Up to now we zap indirections as part of the occurence analyser.
      But this is bogus.  The indirection zapper does the following:
      	x_local = <expression>
      	x_exported = x_local
      where x_exported is exported, and x_local is not, then we
      replace it with this:
      	x_exported = <expression>
      	x_local = x_exported
      But this is plain wrong if x_exported has a RULE that mentions
      something (f, say) in ...bindings.., because 'f' will then die.
      After hacking a few solutions, I've eventually simply made the indirection
      zapping into a separate pass (which is cleaner anyway), which wraps the
      entire program back into a single Rec if the bad thing can happen.
      On the way I've made indirection-zapping work in Recs too, which wasn't the
      case before.
      * Move the zapper from OccurAnal into SimplCore
      * Tidy up the printing of pragmas (PprCore and friends)
      * Add a new function Rules.addRules
      * Merge rules in the indirection zapper (previously one set was discarded)
  6. 24 Dec, 2004 1 commit
    • simonpj's avatar
      [project @ 2004-12-24 16:14:36 by simonpj] · 339d5220
      simonpj authored
                Refactor the simplifier
      Driven by a GADT bug, I have refactored the simpifier, and the way GHC
      treats substitutions.  I hope I have gotten it right.  Be cautious about updating.
      * coreSyn/Subst.lhs has gone
      * coreSyn/CoreSubst replaces it, except that it's quite a bit simpler
      * simplCore/SimplEnv is added, and contains the simplifier-specific substitution
      Previously Subst was trying to be all things to all men, and that was making
      it Too Complicated.
      There may be a little more code now, but it's much easier to understand.
  7. 23 Dec, 2004 1 commit
  8. 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
  9. 21 Dec, 2004 1 commit
    • simonpj's avatar
      [project @ 2004-12-21 12:22:22 by simonpj] · 79a8b87c
      simonpj authored
           Improve handling of lexically scoped type variables
      If we have
      	f :: T a -> a
      	f (x :: T b) = ...
      then the lexically scoped variable 'b' should refer to the rigid
      type variable 'a', without any intervening wobbliness.  Previously
      the in-scope type variables were always mutable TyVars, which were
      instantatiated to point to the type they were bound to; but since
      the advent of GADTs the intervening mutable type variable is a bad
        * In the type environment, ATyVar now carries a type
        * The call to refineTyVars in tc_pat on SigPatIn
          finds the types by matching
        * Then tcExtendTyVarEnv3 extends the type envt appropriately
      Rater a lot of huff and puff, but it's quite natural for ATyVar
      to contain a type.
      Various other small nomenclature changes along the way.
  10. 20 Dec, 2004 1 commit
    • simonpj's avatar
      [project @ 2004-12-20 17:16:24 by simonpj] · c45a0ac5
      simonpj authored
      	Deal properly with dual-renaming
      When comparing types and terms, and during matching, we are faced
      	\x.e1	~   \y.e2
      There are many pitfalls here, and GHC has never done the job properly.
      Now, at last it does, using a new abstraction VarEnv.RnEnv2.  See
      comments there for how it works.
      There are lots of consequential changes to use the new stuff, especially
      	types/Type (type comparison), 
      	types/Unify (matching on types)
      	coreSyn/CoreUtils (equality on expressions), 
      	specialise/Rules (matching).
      I'm not 100% certain of that I've covered all the bases, so let me
      know if something unexpected happens after you update.  Maybe wait until
      a nightly build has worked ok first!
  11. 06 Dec, 2004 1 commit
    • simonpj's avatar
      [project @ 2004-12-06 10:58:06 by simonpj] · bfb87645
      simonpj authored
      	Bug in specialisation
      Laszlo managed to get a function like this:
      	foo :: Enum a => (# a, Int #)
      The specialiser specialised it, resulting in an unboxed tuple
      binding, which Lint objected to.
      This commit adds a dummy argument to the specialised function, 
      very like the case for strictness analysis.  For example, at
      type Char we'd get
      	foo_char :: State# RealWorld -> (# Char, Int #)
       	foo_char = \_ -> ...
      We use a State# type because it generates no argument-passing code 
      at runtime.  (We should really have some other void type for this 
      purpose, because State# is misleading, but this way avoids extra
  12. 25 Nov, 2004 1 commit
    • simonpj's avatar
      [project @ 2004-11-25 11:36:34 by simonpj] · 1f7da302
      simonpj authored
      	Keep-alive set and Template Haskell quotes
      a) Template Haskell quotes should be able to mention top-leve
         things without resorting to lifting.  Example
      	module Foo( foo ) where
      	  f x = x
      	  foo = [| f 4 |]
         Here the reference to 'f' is ok; no need to 'lift' it.
         The relevant changes are in TcExpr.tcId
      b) However, we must take care not to discard the binding for f,
         so we add it to the 'keep-alive' set for the module.  I've
         now made this into (another) mutable bucket, tcg_keep, 
         in the TcGblEnv
      c) That in turn led me to look at the handling of orphan rules;
         as a result I made IdCoreRule into its own data type, which
         has simle but non-local ramifications
  13. 30 Sep, 2004 1 commit
    • simonpj's avatar
      [project @ 2004-09-30 10:35:15 by simonpj] · 23f40f0e
      simonpj authored
      	Add Generalised Algebraic Data Types
      This rather big commit adds support for GADTs.  For example,
          data Term a where
       	  Lit :: Int -> Term Int
      	  App :: Term (a->b) -> Term a -> Term b
      	  If  :: Term Bool -> Term a -> Term a
          eval :: Term a -> a
          eval (Lit i) = i
          eval (App a b) = eval a (eval b)
          eval (If p q r) | eval p    = eval q
          		    | otherwise = eval r
      Lots and lots of of related changes throughout the compiler to make
      this fit nicely.
      One important change, only loosely related to GADTs, is that skolem
      constants in the typechecker are genuinely immutable and constant, so
      we often get better error messages from the type checker.  See
      There's a new module types/Unify.lhs, which has purely-functional
      unification and matching for Type. This is used both in the typechecker
      (for type refinement of GADTs) and in Core Lint (also for type refinement).
  14. 17 Aug, 2004 1 commit
    • simonpj's avatar
      [project @ 2004-08-17 15:23:47 by simonpj] · 59c796f8
      simonpj authored
      	Use merge-sort not quicksort
      	Nuke quicksort altogether
      Quicksort has O(n**2) behaviour worst case, and this occasionally bites.
      In particular, when compiling large files consisting only of static data,
      we get loads of top-level delarations -- and that led to more than half the
      total compile time being spent in the strongly connected component analysis
      for the occurrence analyser.  Switching to merge sort completely solved the
      I've nuked quicksort altogether to make sure this does not happen again.
  15. 21 Apr, 2004 1 commit
    • simonpj's avatar
      [project @ 2004-04-21 12:45:54 by simonpj] · 711ede5f
      simonpj authored
      Do a much better job of slurping RULES.  
      Now that stuff is slurped in lazily, as the simplifier pokes on it,
      we may not get the rules as early as we might wish.  In the current
      HEAD, no new rules are slurped in after the beginning of SimplCore,
      and that means we permanently miss many rules.
      This commit arranges that every time round the simplifier loop we
      slurp in any new rules, and put them into the in-scope set, where the
      simplifier can find them.
      It's still possible that a rule might be slurped in a little later than
      in earlier versions of GHC, leading to more simplifier iterations,
      but let's see if that turns out to be a problem in practice.
  16. 02 Apr, 2004 1 commit
  17. 17 Dec, 2003 1 commit
    • simonpj's avatar
      [project @ 2003-12-17 11:29:40 by simonpj] · ca0b7c66
      simonpj authored
        Fix a subtle loop in the context-reduction machinery
      This bug was provoked by a recent change: when trying to prove
      a constraint C, TcSimplify.reduce now adds C to the database before
      trying to prove C, thus building recursive dictionaries.
      Two bugs
      a) If we add C's superclasses (which we were) we can now build a
         bogusly-recursive dictionary (see Note [SUPERCLASS-LOOP]).
         Solution: in reduce, add C only (via addIrred NoSCs) and then
         later use addWanted to add its definition plus SCs.
      b) Since we can have recursive definitions, the superclass-loop
         handling machinery (findAllDeps) must carry its visited-set
         with it (which it was not doing before)
      The main file is TcSimplify; but I modified a bunch of others to
      take advantage of new function extendVarSetList
  18. 17 Nov, 2003 1 commit
  19. 29 Oct, 2003 1 commit
    • simonpj's avatar
      [project @ 2003-10-29 18:14:27 by simonpj] · 7c3d4a1f
      simonpj authored
      Fix a bad consequence of the new story for the generic toT/fromT functions
      derived from data types declarations. The problem was that they were being
      generated and then discarded by the simplifier, because there was nothing
      keeping them alive.
      This commit
        * Adds a field tcg_keep to the TcGblEnv, which records things
          to be kept alive;
        * Makes the desugarer pin the keep-alive flag on each binding
          (it's actually a call to setIdLocalExported)
        * Removes that job from updateBinders in SimplCore
      It's somewhat tiresome, but not really difficult.
  20. 13 Oct, 2003 1 commit
    • simonpj's avatar
      [project @ 2003-10-13 10:43:02 by simonpj] · 7e7c11b2
      simonpj authored
      Deal corectly with rules for Ids defined in this module,
      even when they are imported (as orphans) from other modules.
      The epicentre for this stuff is SimplCore.
  21. 09 Oct, 2003 1 commit
    • simonpj's avatar
      [project @ 2003-10-09 11:58:39 by simonpj] · 98688c6e
      simonpj authored
      		GHC heart/lung transplant
      This major commit changes the way that GHC deals with importing
      types and functions defined in other modules, during renaming and
      typechecking.  On the way I've changed or cleaned up numerous other
      things, including many that I probably fail to mention here.
      Major benefit: GHC should suck in many fewer interface files when
      compiling (esp with -O).  (You can see this with -ddump-rn-stats.)
      It's also some 1500 lines of code shorter than before.
      **	So expect bugs!  I can do a 3-stage bootstrap, and run
      **	the test suite, but you may be doing stuff I havn't tested.
      ** 	Don't update if you are relying on a working HEAD.
      In particular, (a) External Core and (b) GHCi are very little tested.
      	But please, please DO test this version!
      		Big things
      Interface files, version control, and importing declarations
      * There is a totally new data type for stuff that lives in interface files:
      	Original names			IfaceType.IfaceExtName
      	Types				IfaceType.IfaceType
      	Declarations (type,class,id)	IfaceSyn.IfaceDecl
      	Unfoldings			IfaceSyn.IfaceExpr
        (Previously we used HsSyn for type/class decls, and UfExpr for unfoldings.)
        The new data types are in iface/IfaceType and iface/IfaceSyn.  They are
        all instances of Binary, so they can be written into interface files.
        Previous engronkulation concering the binary instance of RdrName has
        gone away -- RdrName is not an instance of Binary any more.  Nor does
        Binary.lhs need to know about the ``current module'' which it used to,
        which made it specialised to GHC.
        A good feature of this is that the type checker for source code doesn't
        need to worry about the possibility that we might be typechecking interface
        file stuff.  Nor does it need to do renaming; we can typecheck direct from
        IfaceSyn, saving a whole pass (module TcIface)
      * Stuff from interface files is sucked in *lazily*, rather than being eagerly
        sucked in by the renamer. Instead, we use unsafeInterleaveIO to capture
        a thunk for the unfolding of an imported function (say).  If that unfolding
        is every pulled on, TcIface will scramble over the unfolding, which may
        in turn pull in the interface files of things mentioned in the unfolding.
        The External Package State is held in a mutable variable so that it
        can be side-effected by this lazy-sucking-in process (which may happen
        way later, e.g. when the simplifier runs).   In effect, the EPS is a kind
        of lazy memo table, filled in as we suck things in.  Or you could think
        of it as a global symbol table, populated on demand.
      * This lazy sucking is very cool, but it can lead to truly awful bugs. The
        intent is that updates to the symbol table happen atomically, but very bad
        things happen if you read the variable for the table, and then force a
        thunk which updates the table.  Updates can get lost that way. I regret
        this subtlety.
        One example of the way it showed up is that the top level of TidyPgm
        (which updates the global name cache) to be much more disciplined about
        those updates, since TidyPgm may itself force thunks which allocate new
      * Version numbering in interface files has changed completely, fixing
        one major bug with ghc --make.  Previously, the version of A.f changed
        only if A.f's type and unfolding was textually different.  That missed
        changes to things that A.f's unfolding mentions; which was fixed by
        eagerly sucking in all of those things, and listing them in the module's
        usage list.  But that didn't work with --make, because they might have
        been already sucked in.
        Now, A.f's version changes if anything reachable from A.f (via interface
        files) changes.  A module with unchanged source code needs recompiling
        only if the versions of any of its free variables changes. [This isn't
        quite right for dictionary functions and rules, which aren't mentioned
        explicitly in the source.  There are extensive comments in module MkIface,
        where all version-handling stuff is done.]
      * We don't need equality on HsDecls any more (because they aren't used in
        interface files).  Instead we have a specialised equality for IfaceSyn
        (eqIfDecl etc), which uses IfaceEq instead of Bool as its result type.
        See notes in IfaceSyn.
      * The horrid bit of the renamer that tried to predict what instance decls
        would be needed has gone entirely.  Instead, the type checker simply
        sucks in whatever instance decls it needs, when it needs them.  Easy!
        Similarly, no need for 'implicitModuleFVs' and 'implicitTemplateHaskellFVs'
        etc.  Hooray!
      Types and type checking
      * Kind-checking of types is far far tidier (new module TcHsTypes replaces
        the badly-named TcMonoType).  Strangely, this was one of my
        original goals, because the kind check for types is the Right Place to
        do type splicing, but it just didn't fit there before.
      * There's a new representation for newtypes in TypeRep.lhs.  Previously
        they were represented using "SourceTypes" which was a funny compromise.
        Now they have their own constructor in the Type datatype.  SourceType
        has turned back into PredType, which is what it used to be.
      * Instance decl overlap checking done lazily.  Consider
      	instance C Int b
      	instance C a Int
        These were rejected before as overlapping, because when seeking
        (C Int Int) one couldn't tell which to use.  But there's no problem when
        seeking (C Bool Int); it can only be the second.
        So instead of checking for overlap when adding a new instance declaration,
        we check for overlap when looking up an Inst.  If we find more than one
        matching instance, we see if any of the candidates dominates the others
        (in the sense of being a substitution instance of all the others);
        and only if not do we report an error.
      	     Medium things
      * The TcRn monad is generalised a bit further.  It's now based on utils/IOEnv.lhs,
        the IO monad with an environment.  The desugarer uses the monad too,
        so that anything it needs can get faulted in nicely.
      * Reduce the number of wired-in things; in particular Word and Integer
        are no longer wired in.  The latter required HsLit.HsInteger to get a
        Type argument.  The 'derivable type classes' data types (:+:, :*: etc)
        are not wired in any more either (see stuff about derivable type classes
      * The PersistentComilerState is now held in a mutable variable
        in the HscEnv.  Previously (a) it was passed to and then returned by
        many top-level functions, which was painful; (b) it was invariably
        accompanied by the HscEnv.  This change tidies up top-level plumbing
        without changing anything important.
      * Derivable type classes are treated much more like 'deriving' clauses.
        Previously, the Ids for the to/from functions lived inside the TyCon,
        but now the TyCon simply records their existence (with a simple boolean).
        Anyone who wants to use them must look them up in the environment.
        This in turn makes it easy to generate the to/from functions (done
        in types/Generics) using HsSyn (like TcGenDeriv for ordinary derivings)
        instead of CoreSyn, which in turn means that (a) we don't have to figure
        out all the type arguments etc; and (b) it'll be type-checked for us.
        Generally, the task of generating the code has become easier, which is
        good for Manuel, who wants to make it more sophisticated.
      * A Name now says what its "parent" is. For example, the parent of a data
        constructor is its type constructor; the parent of a class op is its
        class.  This relationship corresponds exactly to the Avail data type;
        there may be other places we can exploit it.  (I made the change so that
        version comparison in interface files would be a bit easier; but in
        fact it tided up other things here and there (see calls to
        Name.nameParent).  For example, the declaration pool, of declararations
        read from interface files, but not yet used, is now keyed only by the 'main'
        name of the declaration, not the subordinate names.
      * New types OccEnv and OccSet, with the usual operations.
        OccNames can be efficiently compared, because they have uniques, thanks
        to the hashing implementation of FastStrings.
      * The GlobalRdrEnv is now keyed by OccName rather than RdrName.  Not only
        does this halve the size of the env (because we don't need both qualified
        and unqualified versions in the env), but it's also more efficient because
        we can use a UniqFM instead of a FiniteMap.
        Consequential changes to Provenance, which has moved to RdrName.
      * External Core remains a bit of a hack, as it was before, done with a mixture
        of HsDecls (so that recursiveness and argument variance is still inferred),
        and IfaceExprs (for value declarations).  It's not thoroughly tested.
      	     Minor things
      * DataCon fields dcWorkId, dcWrapId combined into a single field
        dcIds, that is explicit about whether the data con is a newtype or not.
        MkId.mkDataConWorkId and mkDataConWrapId are similarly combined into
      * Choosing the boxing strategy is done for *source* type decls only, and
        hence is now in TcTyDecls, not DataCon.
      * WiredIn names are distinguished by their n_sort field, not by their location,
        which was rather strange
      * Define Maybes.mapCatMaybes :: (a -> Maybe b) -> [a] -> [b]
        and use it here and there
      * Much better pretty-printing of interface files (--show-iface)
      Many, many other small things.
      	     File changes
      * New iface/ subdirectory
      * Much of RnEnv has moved to iface/IfaceEnv
      * MkIface and BinIface have moved from main/ to iface/
      * types/Variance has been absorbed into typecheck/TcTyDecls
      * RnHiFiles and RnIfaces have vanished entirely.  Their
        work is done by iface/LoadIface
      * hsSyn/HsCore has gone, replaced by iface/IfaceSyn
      * typecheck/TcIfaceSig has gone, replaced by iface/TcIface
      * typecheck/TcMonoType has been renamed to typecheck/TcHsType
      * basicTypes/Var.hi-boot and basicTypes/Generics.hi-boot have gone altogether
  22. 18 Feb, 2003 1 commit
  23. 12 Feb, 2003 1 commit
    • simonpj's avatar
      [project @ 2003-02-12 15:01:31 by simonpj] · 42b63073
      simonpj authored
        Big upheaval to the way that constructors are named
      This commit enshrines the new story for constructor names.  We could never
      really get External Core to work nicely before, but now it does.
      The story is laid out in detail in the Commentary
      so I will not repeat it here.
      	[Manuel: the commentary isn't being updated, apparently.]
      However, the net effect is that in Core and in External Core, contructors look
      like constructors, and the way things are printed is all consistent.
      It is a fairly pervasive change (which is why it has been so long postponed),
      but I hope the question is now finally closed.
      All the libraries compile etc, and I've run many tests, but doubtless there will
      be some dark corners.
  24. 13 Sep, 2002 1 commit
    • simonpj's avatar
      [project @ 2002-09-13 15:02:25 by simonpj] · 9af77fa4
      simonpj authored
      	Make Template Haskell into the HEAD
      This massive commit transfers to the HEAD all the stuff that
      Simon and Tim have been doing on Template Haskell.  The
      meta-haskell-branch is no more!
      WARNING: make sure that you
        * Update your links if you are using link trees.
          Some modules have been added, some have gone away.
        * Do 'make clean' in all library trees.
          The interface file format has changed, and you can
          get strange panics (sadly) if GHC tries to read old interface files:
          e.g.  ghc-5.05: panic! (the `impossible' happened, GHC version 5.05):
      	  Binary.get(TyClDecl): ForeignType
        * You need to recompile the rts too; Linker.c has changed
      However the libraries are almost unaltered; just a tiny change in
      Base, and to the exports in Prelude.
      NOTE: so far as TH itself is concerned, expression splices work
      fine, but declaration splices are not complete.
      		The main change
      The main structural change: renaming and typechecking have to be
      interleaved, because we can't rename stuff after a declaration splice
      until after we've typechecked the stuff before (and the splice
      * Combine the renamer and typecheker monads into one
      	(TcRnMonad, TcRnTypes)
        These two replace TcMonad and RnMonad
      * Give them a single 'driver' (TcRnDriver).  This driver
        replaces TcModule.lhs and Rename.lhs
      * The haskell-src library package has a module
        which defines the Haskell data type seen by the TH programmer.
      * New modules:
      	hsSyn/Convert.hs 	converts THSyntax -> HsSyn
      	deSugar/DsMeta.hs 	converts HsSyn -> THSyntax
      * New module typecheck/TcSplice type-checks Template Haskell splices.
      		Linking stuff
      * ByteCodeLink has been split into
      	ByteCodeLink	(which links)
      	ByteCodeAsm	(which assembles)
      * New module ghci/ObjLink is the object-code linker.
      * compMan/CmLink is removed entirely (was out of place)
        Ditto CmTypes (which was tiny)
      * Linker.c initialises the linker when it is first used (no need to call
        initLinker any more).  Template Haskell makes it harder to know when
        and whether to initialise the linker.
      	Gathering the LIE in the type checker
      * Instead of explicitly gathering constraints in the LIE
      	tcExpr :: RenamedExpr -> TcM (TypecheckedExpr, LIE)
        we now dump the constraints into a mutable varabiable carried
        by the monad, so we get
      	tcExpr :: RenamedExpr -> TcM TypecheckedExpr
        Much less clutter in the code, and more efficient too.
        (Originally suggested by Mark Shields.)
      		Remove "SysNames"
      Because the renamer and the type checker were entirely separate,
      we had to carry some rather tiresome implicit binders (or "SysNames")
      along inside some of the HsDecl data structures.  They were both
      tiresome and fragile.
      Now that the typechecker and renamer are more intimately coupled,
      we can eliminate SysNames (well, mostly... default methods still
      carry something similar).
      		Clean up HsPat
      One big clean up is this: instead of having two HsPat types (InPat and
      OutPat), they are now combined into one.  This is more consistent with
      the way that HsExpr etc is handled; there are some 'Out' constructors
      for the type checker output.
      	HsPat.InPat	--> HsPat.Pat
      	HsPat.OutPat	--> HsPat.Pat
      	No 'pat' type parameter in HsExpr, HsBinds, etc
      	Constructor patterns are nicer now: they use
      	for the three cases of constructor patterns:
      		prefix, infix, and record-bindings
      	The *same* data type HsConDetails is used in the type
      	declaration of the data type (HsDecls.TyData)
      Lots of associated clean-up operations here and there.  Less code.
      Everything is wonderful.
  25. 09 Sep, 2002 1 commit
  26. 02 Sep, 2002 1 commit
    • simonpj's avatar
      [project @ 2002-09-02 16:31:34 by simonpj] · 80e363e7
      simonpj authored
      Do not specialise functions that take implicit parameters.
      The specialisation mechanism doesn't work for them, because
      their implicit args are not driven by their type args (unlike
      the implicit dictionary parameters)
  27. 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
      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.
  28. 05 Apr, 2002 1 commit
  29. 20 Mar, 2002 1 commit
  30. 18 Mar, 2002 1 commit
  31. 04 Mar, 2002 1 commit
    • simonmar's avatar
      [project @ 2002-03-04 17:01:26 by simonmar] · 0171936c
      simonmar authored
      Binary Interface Files - stage 1
      This commit changes the default interface file format from text to
      binary, in order to improve compilation performace.
      To view an interface file, use 'ghc --show-iface Foo.hi'.
      utils/Binary.hs is the basic Binary I/O library, based on the nhc98
      binary I/O library but much stripped-down and working in terms of
      bytes rather than bits, and with some special features for GHC: it
      remembers which Module is being emitted to avoid dumping too many
      qualified names, and it keeps track of a "dictionary" of FastStrings
      so that we don't dump the same FastString more than once into the
      binary file.  I'll make a generic version of this for the libraries at
      some point.
      main/BinIface.hs contains most of the Binary instances.  Some
      instances are in the same module as the data type (RdrName, Name,
      OccName in particular).  Most instances were generated using a
      modified version of DrIFT, which I'll commit later.  However, editing
      them by hand isn't hard (certainly easier than modifying
      The first thing in a binary interface is the interface version, so
      nice error messages will be generated if the binary format changes and
      you still have old interfaces lying around.  The version also now
      includes the "way" as an extra sanity check.
      Other changes
      I don't like the way FastStrings contain both hashed strings (with
      O(1) comparison) and literal C strings (with O(n) comparison).  So as
      a first step to separating these I made serveral "literal" type
      strings into hashed strings.  SLIT() still generates a literal, and
      now FSLIT() generates a hashed string.  With DEBUG on, you'll get a
      warning if you try to compare any SLIT()s with anything, and the
      compiler will fall over if you try to dump any literal C strings into
      an interface file (usually indicating a use of SLIT() which should be
      mkSysLocal no longer re-encodes its FastString argument each time it
      is called.
      I also fixed the -pgm options so that the argument can now optionally
      be separted from the option.
      Bugfix: PrelNames declared Names for several comparison primops, eg.
      eqCharName, eqIntName etc. but these had different uniques from the
      real primop names.  I've moved these to PrimOps and defined them using
      mkPrimOpIdName instead, and deleted some for which we don't have real
      primops (Manuel: please check that things still work for you after
      this change).
  32. 01 Nov, 2001 2 commits
    • simonpj's avatar
      [project @ 2001-11-01 13:20:42 by simonpj] · 2ca9a768
      simonpj authored
    • simonpj's avatar
      [project @ 2001-11-01 13:20:05 by simonpj] · 51666a19
      simonpj authored
      	Fix a unboxed-binding bug in SpecConstr
      	[HEAD only]
      This fixes a rather obscure bug in the constructor
      specialiser discovered by Ralf Hinze.  It was
      generating a specialised version of the function
      with no arguments --- and the function returned an
      unboxed type.
      Solution: same as for worker-wrapper; add a dummy
      Several files are affected because I added
      CoreUtils.mkPiTypes, as a useful helper function.
  33. 30 Oct, 2001 1 commit
  34. 25 Oct, 2001 1 commit
    • sof's avatar
      [project @ 2001-10-25 02:13:10 by sof] · 9e933350
      sof authored
      - Pet peeve removal / code tidyup, replaced various sub-optimal
        uses of 'length' with something a bit better, i.e., replaced
        the following patterns
         *  length as `cmpOp` length bs
         *  length as `cmpOp` val   -- incl. uses where val == 1 and val == 0
         *  {take,drop,splitAt} (length as) bs
         *  length [ () | pat <- as ]
        with uses of misc Util functions.
        I'd be surprised if there's a noticeable reduction in running
        times as a result of these changes, but every little bit helps.
        [ The changes have been tested wrt testsuite/ - I'm seeing a couple
          of unexpected breakages coming from CorePrep, but I'm currently
          assuming that these are due to other recent changes. ]
      - compMan/CompManager.lhs: restored 4.08 compilability + some code
      None of these changes are HEADworthy.
  35. 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
      	    "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
      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,
      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
      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!
  36. 14 Sep, 2001 1 commit
    • simonpj's avatar
      [project @ 2001-09-14 15:51:41 by simonpj] · 5ab261bb
      simonpj authored
      	Add a rule-check pass
      	(special request by Manuel)
      	DO NOT merge with stable
      The flag
      	-frule-check foo
      will report all sites at which RULES whose name starts with "foo.."
      might apply, but in fact the arguments don't match so the rule
      doesn't apply.
      The pass is run right after all the core-to-core passes.  (Next thing
      to do: make the core-to-core script external, so you can fiddle with
      it.  Meanwhile, the core-to-core script is in
      so you can move the CoreDoRuleCheck line around if you want.
      The format of the report is experimental: Manuel, feel free to fiddle
      with it.
      Most of the code is in specialise/Rules.lhs
      Incidental changes
      Change BuiltinRule so that the rule name is accessible
      without actually successfully applying the rule.  This
      change affects quite a few files in a trivial way.
  37. 24 Aug, 2001 1 commit
  38. 25 Jun, 2001 2 commits
    • simonpj's avatar
      [project @ 2001-06-25 14:36:04 by simonpj] · a5ded1f8
      simonpj authored
      Import wibbles
    • 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.