This project is mirrored from https://gitlab.haskell.org/ghc/ghc.git. Pull mirroring failed .
Repository mirroring has been paused due to too many failed attempts. It can be resumed by a project maintainer.
Last successful update .
  1. 15 Sep, 2004 1 commit
    • ross's avatar
      [project @ 2004-09-15 17:48:08 by ross] · daf67985
      ross authored
      arrow notation: allow arrow applications (f -< a) to take a non-empty
      command stack, as suggested by Sebastian Boldt <Sebastian.Boldt@arcor.de>.
      daf67985
  2. 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
      ca0b7c66
  3. 10 Dec, 2003 1 commit
    • simonmar's avatar
      [project @ 2003-12-10 14:15:16 by simonmar] · 55042138
      simonmar authored
      Add accurate source location annotations to HsSyn
      -------------------------------------------------
      
      Every syntactic entity in HsSyn is now annotated with a SrcSpan, which
      details the exact beginning and end points of that entity in the
      original source file.  All honest compilers should do this, and it was
      about time GHC did the right thing.
      
      The most obvious benefit is that we now have much more accurate error
      messages; when running GHC inside emacs for example, the cursor will
      jump to the exact location of an error, not just a line somewhere
      nearby.  We haven't put a huge amount of effort into making sure all
      the error messages are accurate yet, so there could be some tweaking
      still needed, although the majority of messages I've seen have been
      spot-on.
      
      Error messages now contain a column number in addition to the line
      number, eg.
      
         read001.hs:25:10: Variable not in scope: `+#'
      
      To get the full text span info, use the new option -ferror-spans.  eg.
      
         read001.hs:25:10-11: Variable not in scope: `+#'
      
      I'm not sure whether we should do this by default.  Emacs won't
      understand the new error format, for one thing.
      
      In a more elaborate editor setting (eg. Visual Studio), we can arrange
      to actually highlight the subexpression containing an error.  Eventually
      this information will be used so we can find elements in the abstract
      syntax corresponding to text locations, for performing high-level editor
      functions (eg. "tell me the type of this expression I just highlighted").
      
      Performance of the compiler doesn't seem to be adversely affected.
      Parsing is still quicker than in 6.0.1, for example.
      
      Implementation:
      
      This was an excrutiatingly painful change to make: both Simon P.J. and
      myself have been working on it for the last three weeks or so.  The
      basic changes are:
      
       - a new datatype SrcSpan, which represents a beginning and end position
         in a source file.
      
       - To reduce the pain as much as possible, we also defined:
      
            data Located e = L SrcSpan e
      
       - Every datatype in HsSyn has an equivalent Located version.  eg.
      
            type LHsExpr id = Located (HsExpr id)
      
         and pretty much everywhere we used to use HsExpr we now use
         LHsExpr.  Believe me, we thought about this long and hard, and
         all the other options were worse :-)
      
      
      Additional changes/cleanups we made at the same time:
      
        - The abstract syntax for bindings is now less arcane.  MonoBinds
          and HsBinds with their built-in list constructors have gone away,
          replaced by HsBindGroup and HsBind (see HsSyn/HsBinds.lhs).
      
        - The various HsSyn type synonyms have now gone away (eg. RdrNameHsExpr,
          RenamedHsExpr, and TypecheckedHsExpr are now HsExpr RdrName,
          HsExpr Name, and HsExpr Id respectively).
      
        - Utilities over HsSyn are now collected in a new module HsUtils.
          More stuff still needs to be moved in here.
      
        - MachChar now has a real Char instead of an Int.  All GHC versions that
          can compile GHC now support 32-bit Chars, so this was a simplification.
      55042138
  4. 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
  5. 20 Sep, 2003 1 commit
    • ross's avatar
      [project @ 2003-09-20 17:24:47 by ross] · 71d25e0a
      ross authored
      fixes to desugaring of arrow notation:
      
      * fix free variable calculation for if's
      
      * various fixes for case
      
      please merge to STABLE
      71d25e0a
  6. 16 Jul, 2003 1 commit
    • ross's avatar
      [project @ 2003-07-16 08:49:01 by ross] · 98232a61
      ross authored
      Arrow notation: add a new (more primitive) form of command:
      
      	cmd ::= ... | cmd aexp
      
      analogous to ordinary application, and also represented using HsApp.
      To avoid an overlap, the syntax for combining forms is changed to
      
      	(|aexp cmd1 ... cmdn|)
      98232a61
  7. 15 Jul, 2003 1 commit
  8. 02 Jul, 2003 1 commit
  9. 24 Jun, 2003 2 commits
    • ross's avatar
      [project @ 2003-06-24 09:44:44 by ross] · 81b7a3fb
      ross authored
      fix bug with ExprStmt, plus some cleaning up.
      81b7a3fb
    • simonpj's avatar
      [project @ 2003-06-24 07:58:18 by simonpj] · 16e4ce4c
      simonpj authored
      ----------------------------------------------
      	Add support for Ross Paterson's arrow notation
      	----------------------------------------------
      
      Ross Paterson's ICFP'01 paper described syntax to support John Hughes's
      "arrows", rather as do-notation supports monads.  Except that do-notation is
      relatively modest -- you can write monads by hand without much trouble --
      whereas arrow-notation is more-or-less essential for writing arrow programs.
      It desugars to a massive pile of tuple construction and selection!
      
      For some time, Ross has had a pre-processor for arrow notation, but the
      resulting type error messages (reported in terms of the desugared code)
      are impenetrable.  This commit integrates the syntax into GHC.  The
      type error messages almost certainly still require tuning, but they should
      be better than with the pre-processor.
      
      Main syntactic changes (enabled with -farrows)
      
         exp ::= ... | proc pat -> cmd
      
         cmd ::= exp1 -<  exp2   |  exp1 >-  exp2
      	|  exp1 -<< exp2   |  exp1 >>- exp2
      	| \ pat1 .. patn -> cmd
      	| let decls in cmd
      	| if exp then cmd1 else cmd2
      	| do { cstmt1 .. cstmtn ; cmd }
      	| (| exp |) cmd1 .. cmdn
      	| cmd1 qop cmd2
      	| case exp of { calts }
      
         cstmt :: = let decls
      	 |   pat <- cmd
      	 |   rec { cstmt1 .. cstmtn }
      	 |   cmd
      
      New keywords and symbols:
      	proc rec
      	-<   >-   -<<   >>-
      	(|  |)
      
      The do-notation in cmds was not described in Ross's ICFP'01 paper; instead
      it's in his chapter in The Fun of Programming (Plagrave 2003).
      
      The four arrow-tail forms (-<) etc cover
        (a) which order the pices come in (-<  vs  >-), and
        (b) whether the locally bound variables can be used in the
      		arrow part (-<  vs  -<<) .
      In previous presentations, the higher-order-ness (b) was inferred,
      but it makes a big difference to the typing required so it seems more
      consistent to be explicit.
      
      The 'rec' form is also available in do-notation:
        * you can use 'rec' in an ordinary do, with the obvious meaning
        * using 'mdo' just says "infer the minimal recs"
      
      
      Still to do
      ~~~~~~~~~~~
      Top priority is the user manual.
      
      The implementation still lacks an implementation of
      the case form of cmd.
      
      
      Implementation notes
      ~~~~~~~~~~~~~~~~~~~~
      Cmds are parsed, and indeed renamed, as expressions.  The type checker
      distinguishes the two.
      16e4ce4c