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--------------------------------------
	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.

Type variables created by the typechecker didn't have the correct
NameSpace: they were in the Var namespace rather than the TyVar
namespace, which can lead to strange warnings about quantified type
variables being not mentioned in the type when DEBUG is on.

Name:
	- added mkSystemNameEncoded for use when the string
	  is already encoded (saves re-encoding the string every
	  time)

	- added mkSystemTvNameEncoded for making a type variable
	  name, as above

Var:
	- use mkSystemTvNameEncoded when making type variables

Id:
	- add mkSysLocalUnencoded for the (rare) case when
	  the string needs encoding

TcMType:
	- use mkSystemTvNameEncoded rather than mkSystemName for
	  making type variables

SetLevels:
	- use mkSysLocalUnencoded since the names generated here
	  need encoding.

Use Unique.getKey instead of Unique.u2i (they are the same function).

Import wibbles

Misc cleanup: remove the iface pretty-printing style, and clean up
bits of StringBuffer that aren't required any more.

------------------------
	Change
		GlobalName --> ExternalName
		LocalName  ->  InternalName
	------------------------

For a long time there's been terminological confusion between

	GlobalName vs LocalName	 (property of a Name)
	GlobalId vs LocalId	 (property of an Id)

I've now changed the terminology for Name to be

	ExternalName vs InternalName

I've also added quite a bit of documentation in the Commentary.

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
ParseIface.y).

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
FSLIT()).

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).

Make the OccName and SrcLoc fields of a Name strict, to eliminate
space leaks.  This doesn't hurt performance.

Fix codegen globalisation for -split-objs

-------------------------------------------
	Towards generalising 'foreign' declarations
	-------------------------------------------

This is a first step towards generalising 'foreign' declarations to
handle langauges other than C.  Quite a lot of files are touched,
but nothing has really changed.  Everything should work exactly as
before.

	But please be on your guard for ccall-related bugs.

Main things

Basic data types: ForeignCall.lhs
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
* Remove absCSyn/CallConv.lhs

* Add prelude/ForeignCall.lhs.  This defines the ForeignCall
  type and its variants

* Define ForeignCall.Safety to say whether a call is unsafe
  or not (was just a boolean).  Lots of consequential chuffing.

* Remove all CCall stuff from PrimOp, and put it in ForeignCall


Take CCallOp out of the PrimOp type (where it was always a glitch)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
* Add IdInfo.FCallId variant to the type IdInfo.GlobalIdDetails,
	along with predicates Id.isFCallId, Id.isFCallId_maybe

* Add StgSyn.StgOp, to sum PrimOp with FCallOp, because it
  *is* useful to sum them together in Stg and AbsC land.  If
  nothing else, it minimises changes.


Also generally rename "CCall" stuff to "FCall" where it's generic
to all foreign calls.

--------------------
	A major hygiene pass
	--------------------

1. The main change here is to

	Move what was the "IdFlavour" out of IdInfo,
	and into the varDetails field of a Var

   It was a mess before, because the flavour was a permanent attribute
   of an Id, whereas the rest of the IdInfo was ephemeral.  It's
   all much tidier now.

   Main places to look:

	   Var.lhs	Defn of VarDetails
	   IdInfo.lhs	Defn of GlobalIdDetails

   The main remaining infelicity is that SpecPragmaIds are right down
   in Var.lhs, which seems unduly built-in for such an ephemeral thing.
   But that is no worse than before.


2. Tidy up the HscMain story a little.  Move mkModDetails from MkIface
   into CoreTidy (where it belongs more nicely)

   This was partly forced by (1) above, because I didn't want to make
   DictFun Ids into a separate kind of Id (which is how it was before).
   Not having them separate means we have to keep a list of them right
   through, rather than pull them out of the bindings at the end.

3. Add NameEnv as a separate module (to join NameSet).

4. Remove unnecessary {-# SOURCE #-} imports from FieldLabel.

Print debug uniques consistently in base64

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.

Workers get local names initially; nuke mkDerivedName

Re-engineer the transition from Core to STG syntax.  Main changes in
this commit:

  - a new pass, CoreSat, handles saturation of constructors and PrimOps,
    and puts the syntax into STG-like normal form (applications to atoms
    only, etc), modulo type applications and Notes.

  - CoreToStg is now done at the same time as StgVarInfo.  Most of the
    contents of StgVarInfo.lhs have been copied into CoreToStg.lhs and
    some simplifications made.

less major changes:

  - globalisation of names for the purposes of object splitting is
    now done by the C code generator (which is the Right Place in
    principle, but it was a bit fiddly).

  - CoreTidy now does cloning of local binders and collection of arity
    info.  The IdInfo from CoreTidy is now *almost* the final IdInfo we
    put in the interface file, except for CafInfo.  I'm going to move
    the CafInfo collection into CoreTidy in due course too.

  - and some other minor tidyups while I was in cluster-bomb commit mode.

Dont print uniques in interface files; tidying should have sorted it out

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.

Version management

[WARNING: may not work!  Don't update till I've tested it.]

This commit is a first stab at getting version management to
work properly.  The main trick is to get consistent naming when
comparing old and new versions of the same module.  

Some functionality has moved arond between
  coreSyn/CoreTidy, which tidies up the result of
			the middle end of the compiler
	Main change: now responsible for figuring out which
	Ids are "external" (i.e visible to importing modules),
	and constructing the final IdInfo for each Id

  main/MkIface, which produces the ModIface and ModDetails
		for the module being compiled
	Main change: CoreTidy does more, so MkIface does less

  stgSyn/CoreToStg, which converts Core to STG
	Main change: responsible for globalising internal
	names when we are doing object code splitting 
			
The game plan is documented at the top of CoreTidy.

Split HscResult into HscFail | HscNoRecomp | HscRecomp, and clean up
producers and consumers of such.  In particular, if no recompilation
happens, the resulting iface is put into the HIT instead of being
thrown away.

Also (trivial) unify functions *ModuleInThisPackage with *HomeModule.

Fix another naming bug

Changing the way we know whether
something is exported.

THIS COMMIT WON'T EVEN COMPILE
(I'm doing it to transfer from my laptop.)
Wait till later today before updating.

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

More renamer commits

Versioning now works properly I think.

The main irritation is that interface files now have fuly-qualified names for
*everything*, even things defined in that module.  This is a deficiency in
the pretty printing for interface files.  Probable solution: add something
to the SDoc styles.  But not today.

PrelBase compiles!

Improve MkIface; get ready for NameEnv.lhs

More tidying up; esp of isLocallyDefined

Fix Name

First steps to making it work

Wibble

Tons of stuff for the mornings work

Fix enough renamer bits to get going again on the typechecker.
HACK ALERT: RnIfaces is almost completely #ifdef'd out!

Track Simon's Module changes.

isLocalModule ==> isModuleInThisPackage

Fix up pprName.  So much simpler than the original that it will
doubtless require fixing later.

Mainly renamer

Remove wired-in names.  Partially propogated.

Move FAST_INT and FAST_BOOL into their own module FastTypes, replacing
the macro definitions in HsVersions.h with real definitions.  Change
most of the names in the process.

Now we don't get bogus imports of GlaExts all over the place, and
-fwarn-unused-imports is less noisy.

Rename a bunch of mkSrc* things into mk*'s.

--------------------------------------
	Adding generics		SLPJ Oct 2000
	--------------------------------------

This big commit adds Hinze/PJ-style generic class definitions, based
on work by Andrei Serjantov.  For example:

  class Bin a where
    toBin   :: a -> [Int]
    fromBin :: [Int] -> (a, [Int])

    toBin {| Unit |}    Unit	  = []
    toBin {| a :+: b |} (Inl x)   = 0 : toBin x
    toBin {| a :+: b |} (Inr y)   = 1 : toBin y
    toBin {| a :*: b |} (x :*: y) = toBin x ++ toBin y


    fromBin {| Unit |}    bs      = (Unit, bs)
    fromBin {| a :+: b |} (0:bs)  = (Inl x, bs')    where (x,bs') = fromBin bs
    fromBin {| a :+: b |} (1:bs)  = (Inr y, bs')    where (y,bs') = fromBin bs
    fromBin {| a :*: b |} bs  	  = (x :*: y, bs'') where (x,bs' ) = fromBin bs
							  (y,bs'') = fromBin bs'

Now we can say simply

  instance Bin a => Bin [a]

and the compiler will derive the appropriate code automatically.

		(About 9k lines of diffs.  Ha!)


Generic related things
~~~~~~~~~~~~~~~~~~~~~~

* basicTypes/BasicTypes: The EP type (embedding-projection pairs)

* types/TyCon:
	An extra field in an algebraic tycon (genInfo)

* types/Class, and hsSyn/HsBinds:
	Each class op (or ClassOpSig) carries information about whether
	it  	a) has no default method
		b) has a polymorphic default method
		c) has a generic default method
	There's a new data type for this: Class.DefMeth

* types/Generics:
	A new module containing good chunk of the generic-related code
	It has a .hi-boot file (alas).

* typecheck/TcInstDcls, typecheck/TcClassDcl:
	Most of the rest of the generics-related code

* hsSyn/HsTypes:
	New infix type form to allow types of the form
		data a :+: b = Inl a | Inr b

* parser/Parser.y, Lex.lhs, rename/ParseIface.y:
	Deal with the new syntax

* prelude/TysPrim, TysWiredIn:
	Need to generate generic stuff for the wired-in TyCons

* rename/RnSource RnBinds:
	A rather gruesome hack to deal with scoping of type variables
	from a generic patterns.  Details commented in the ClassDecl
	case of RnSource.rnDecl.

	Of course, there are many minor renamer consequences of the
	other changes above.

* lib/std/PrelBase.lhs
	Data type declarations for Unit, :+:, :*:


Slightly unrelated housekeeping
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
* hsSyn/HsDecls:
	ClassDecls now carry the Names for their implied declarations
	(superclass selectors, tycon, etc) in a list, rather than
	laid out one by one.  This simplifies code between the parser
	and the type checker.

* prelude/PrelNames, TysWiredIn:
	All the RdrNames are now together in PrelNames.

* utils/ListSetOps:
	Add finite mappings based on equality and association lists (Assoc a b)
	Move stuff from List.lhs that is related

------------------------------------
	   Mainly PredTypes (28 Sept 00)
	------------------------------------

Three things in this commit:

	1.  Main thing: tidy up PredTypes
	2.  Move all Keys into PrelNames
	3.  Check for unboxed tuples in function args

1. Tidy up PredTypes
~~~~~~~~~~~~~~~~~~~~
The main thing in this commit is to modify the representation of Types
so that they are a (much) better for the qualified-type world.  This
should simplify Jeff's life as he proceeds with implicit parameters
and functional dependencies.  In particular, PredType, introduced by
Jeff, is now blessed and dignified with a place in TypeRep.lhs:

	data PredType  = Class  Class [Type]
		       | IParam Name  Type

Consider these examples:
	f :: (Eq a) => a -> Int
	g :: (?x :: Int -> Int) => a -> Int
	h :: (r\l) => {r} => {l::Int | r}

Here the "Eq a" and "?x :: Int -> Int" and "r\l" are all called
*predicates*, and are represented by a PredType.  (We don't support
TREX records yet, but the setup is designed to expand to allow them.)

In addition, Type gains an extra constructor:

	data Type = .... | PredTy PredType

so that PredType is injected directly into Type.  So the type
	p => t
is represented by
	PredType p `FunTy` t

I have deleted the hackish IPNote stuff; predicates are dealt with entirely
through PredTys, not through NoteTy at all.


2.  Move Keys into PrelNames
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
This is just a housekeeping operation. I've moved all the pre-assigned Uniques
(aka Keys) from Unique.lhs into PrelNames.lhs.  I've also moved knowKeyRdrNames
from PrelInfo down into PrelNames.  This localises in PrelNames lots of stuff
about predefined names.  Previously one had to alter three files to add one,
now only one.

3.  Unboxed tuples
~~~~~~~~~~~~~~~~~~
Add a static check for unboxed tuple arguments.  E.g.
	data T = T (# Int, Int #)
is illegal