1. 08 Aug, 2006 1 commit
    • simonpj@microsoft.com's avatar
      Improve error message · d2b27dcd
      simonpj@microsoft.com authored
      Improve a little-used error message.  Given
      	f :: a -> a
      	f x y = e
      the error says 
      
      	The equations for f have two arguments
      	but its type `a -> a' has only one
      
      (Before, it said "its type `a' has only one" which is bogus.
      d2b27dcd
  2. 10 Jul, 2006 2 commits
  3. 09 Jul, 2006 2 commits
  4. 08 Jul, 2006 1 commit
  5. 07 Aug, 2006 2 commits
    • simonpj@microsoft.com's avatar
      Add -fextended-default-rules and -fmono-pat-binds · 6e0c3f50
      simonpj@microsoft.com authored
      Add -fextended-deafult-rules (in response to Don Stewart's message below),
      and document them.
      
      Also doucument -fmono-pat-binds/-fno-mono-pat-binds, which has been in 
      GHC a few weeks now. 
      
      (The two are in one patch because the diffs were so close together
      that Darcs combined them.)
      
      Simon
      
      
      From: Donald Bruce Stewart [mailto:dons@cse.unsw.edu.au] 
      Sent: 07 August 2006 10:52
      
      While we're thinking about defaulting, I have a question..
      
      ghci uses an extended defaulting system, to allow things like:
              Prelude> reverse []
              []
      to work, and to have the right instance of Show found. The manual says:
      
          "..it is tiresome for the user to have to specify the type, so GHCi extends
          Haskell's type-defaulting rules (Section 4.3.4 of the Haskell 98 Report
          (Revised)) as follows. If the expression yields a set of type constraints
          that are all from standard classes (Num, Eq etc.), and at least one is
          either a numeric class or the Show, Eq, or Ord class, GHCi will try to use
          one of the default types, just as described in the Report. The standard
          defaulting rules require that one of the classes is numeric; the difference
          here is that defaulting is also triggered at least one is Show, Eq, or Ord."
      
      Currently, there is no way to get at this "extended" defaulting for compiled
      modules. However, I have a use case for in fact doing this.
      
      With runtime evaluated Haskell, embedding 'interpreters' (over hs-plugins) is
      easy. lambdabot, for example, implements a sandboxed haskell eval system. But
      it doesn't have access to the defaulting mechanism of ghci, so we have:
      
          dons:: > reverse []
          lambdabot:: Add a type signature
          dons:: > reverse [] :: [()]
          lambdabot:: []
      
      Which is annoying -- newbies wonder why they have to add these extra
      constraints to get a Show instance.
      
      I'm wondering, since the extended defaulting mechanisms are already
      implemented, could they be made available to compiled modules as well,
      perhaps using a flag, -fextended-defaulting? 
      6e0c3f50
    • Simon Marlow's avatar
      add a comment · 25adfa02
      Simon Marlow authored
      25adfa02
  6. 04 Aug, 2006 1 commit
    • simonpj@microsoft.com's avatar
      Do pre-subsumption in the main subsumption check · af20907a
      simonpj@microsoft.com authored
      This patch improves the subsumption check (in TcUnify.tc_sub) so that
      it does pre-subsumption first.  The key code is in the case with
      guard (isSigmaTy actual_ty); note the new call to preSubType.
      
      Shorn of details, the question is this.  Should this hold?
      
      	forall a. a->a   <=   Int -> (forall b. Int)
      
      Really, it should; just instantiate 'a' to Int.  This is just what
      the pre-subsumption phase (which used in function applications),
      will do.
      
      I did a bit of refactoring to achieve this.
      
      Fixes Trac #821.  Test tc205 tests.
      af20907a
  7. 01 Aug, 2006 1 commit
    • simonpj@microsoft.com's avatar
      Make unification robust to a boxy type variable meeting itself · 6493f9d3
      simonpj@microsoft.com authored
      Previously, the implicit assumption in unification is that a boxy
      type variable could never occur on both sides of the unification,
      so that we'd never find 
      	bx5 :=: bx5
      
      But the pre-subsumption stuff really means that the same variable
      can occur on both sides.  Consider
      	forall a. a->Int <= bx5->Int
      Then pre-subumption will find a->bx5; and the full subsumption step 
      will find bx5:=bx5.
      
      However, I think there is still no possiblity of a full occurs-check
      failure; that is, 
      	bx5 :=: Tree bx5
      Although I can't quite see how to prove it!  So I've added a
      DEBUG test in uMetaVar to check for this case.
      6493f9d3
  8. 04 Aug, 2006 1 commit
  9. 03 Aug, 2006 1 commit
  10. 20 Jul, 2006 1 commit
  11. 01 Aug, 2006 1 commit
  12. 29 Jul, 2006 1 commit
    • Ian Lynagh's avatar
      Refactor ghc-pkg · 34b0bd51
      Ian Lynagh authored
      This patch fixes a couple of issues with the
          Be lazier in user config creation, and don't fail on missing configs.
      patch. It puts the createDirectoryIfMissing back in and removes assumptions
      that the package.conf file already exists.
      34b0bd51
  13. 30 Jul, 2006 1 commit
    • Ian Lynagh's avatar
      No functionality changes · ede4c6f2
      Ian Lynagh authored
      Consistently used spaces rather than tabs.
      Removed trailing whitespace.
      Wrapped comments to fit in a standard terminal.
      ede4c6f2
  14. 31 Jul, 2006 1 commit
  15. 28 Jul, 2006 3 commits
  16. 27 Jul, 2006 8 commits
  17. 26 Jul, 2006 6 commits
  18. 25 Jul, 2006 6 commits
    • Simon Marlow's avatar
      Unbox the Unique stored in a Name · ddb04482
      Simon Marlow authored
      I measured that this makes the comiler allocate a bit more, but it
      might also make it faster and reduce residency.  The extra allocation
      is probably just because we're not inlining enough somewhere, so I
      think this change is a step in the right direction.
      ddb04482
    • Simon Marlow's avatar
      optimisations to newUnique · bb3dcf39
      Simon Marlow authored
      It turned out that newUnique was wasting one node of the splittable
      uniq supply per invocation: it took the current supply, split it, used
      the unique from one half and stored the other half in the monad.  In
      other words, the unique in the supply stored in the monad was never
      used.  
      
      This optimisation fixes that and adds a bit of strictness, which
      together lead to small reduction in allocations by the compiler, and
      possibly an improvement in residency (hard to tell for sure when GCs
      move around).
      bb3dcf39
    • Simon Marlow's avatar
      tiny bit of extra strictness · 6e2cffab
      Simon Marlow authored
      6e2cffab
    • Simon Marlow's avatar
      Make a SplitUniqSupply contain an Int# rather than an Int · 39a2bccc
      Simon Marlow authored
      The I# constructor is always removed when we make a unique later
      anyway, so this just saves a bit of time and allocation.
      39a2bccc
    • Simon Marlow's avatar
      3ca54aeb
    • Simon Marlow's avatar
      Remove most of the conflict checking and auto-hiding · b93ff3a3
      Simon Marlow authored
      Now that the module restriction has been lifted, the auto-hiding is
      mostly not required.  GHC itself automatically hides old versions of a
      package.
      b93ff3a3