1. 24 Jan, 2017 1 commit
  2. 19 Jan, 2017 1 commit
    • Richard Eisenberg's avatar
      Update levity polymorphism · e7985ed2
      Richard Eisenberg authored
      This commit implements the proposal in
      https://github.com/ghc-proposals/ghc-proposals/pull/29 and
      https://github.com/ghc-proposals/ghc-proposals/pull/35.
      
      Here are some of the pieces of that proposal:
      
      * Some of RuntimeRep's constructors have been shortened.
      
      * TupleRep and SumRep are now parameterized over a list of RuntimeReps.
      * This
      means that two types with the same kind surely have the same
      representation.
      Previously, all unboxed tuples had the same kind, and thus the fact
      above was
      false.
      
      * RepType.typePrimRep and friends now return a *list* of PrimReps. These
      functions can now work successfully on unboxed tuples. This change is
      necessary because we allow abstraction over unboxed tuple types and so
      cannot
      always handle unboxed tuples specially as we did before.
      
      * We sometimes have to create an Id from a PrimRep. I thus split PtrRep
      * into
      LiftedRep and UnliftedRep, so that the created Ids have the right
      strictness.
      
      * The RepType.RepType type was removed, as it didn't s...
      e7985ed2
  3. 02 Dec, 2016 1 commit
  4. 29 Nov, 2016 1 commit
    • Simon Peyton Jones's avatar
      Zonk the free tvs of a RULE lhs to TyVars · f8c8de8e
      Simon Peyton Jones authored
      Previously we were making them into skolem TcTyVars,
      which is wrong for the output of the type checker, which
      no TcTyVars should surive.
      
      See Note [Zonking the LHS of a RULE] in TcHsSyn
      
      This was flushed out by the new IfaceTcTyVar thing;
      I found some more TcTyVars that were being serialised into
      an interface file, which is wrong wrong wrong.
      f8c8de8e
  5. 25 Nov, 2016 2 commits
    • Simon Peyton Jones's avatar
      Use TyVars in PatSyns · 12eff239
      Simon Peyton Jones authored
      I found that some TcTyVars were lurking in a PatSyn, because
      tc_patsyn_finish was using the TcType -> TcType zonker rather
      than the TcType -> Type zonker.  Eeek.
      
      I fixing this I also tided up function naming a bit (still not
      terrific), and removed the unused TcTyBinder type entirely.
      12eff239
    • Simon Peyton Jones's avatar
      Another major constraint-solver refactoring · 1eec1f21
      Simon Peyton Jones authored
      This patch takes further my refactoring of the constraint
      solver, which I've been doing over the last couple of months
      in consultation with Richard.
      
      It fixes a number of tricky bugs that made the constraint
      solver actually go into a loop, including
      
        Trac #12526
        Trac #12444
        Trac #12538
      
      The main changes are these
      
      * Flatten unification variables (fmvs/fuvs) appear on the LHS
        of a tvar/tyvar equality; thus
                 fmv ~ alpha
        and not
                 alpha ~ fmv
      
        See Note [Put flatten unification variables on the left]
        in TcUnify.  This is implemented by TcUnify.swapOverTyVars.
      
      * Don't reduce a "loopy" CFunEqCan where the fsk appears on
        the LHS:
            F t1 .. tn ~ fsk
        where 'fsk' is free in t1..tn.
        See Note [FunEq occurs-check principle] in TcInteract
      
        This neatly stops some infinite loops that people reported;
        and it allows us to delete some crufty code in reduce_top_fun_eq.
        And it appears to be no loss whatsoever.
      
        As well as fixing loops, ContextStack2 and T5837 both terminate
        when they didn't before.
      
      * Previously we generated "derived shadow" constraints from
        Wanteds, but we could (and sometimes did; Trac #xxxx) repeatedly
        generate a derived shadow from the same Wanted.
      
        A big change in this patch is to have two kinds of Wanteds:
           [WD] behaves like a pair of a Wanted and a Derived
           [W]  behaves like a Wanted only
        See CtFlavour and ShadowInfo in TcRnTypes, and the ctev_nosh
        field of a Wanted.
      
        This turned out to be a lot simpler.  A [WD] gets split into a
        [W] and a [D] in TcSMonad.maybeEmitShaodow.
      
        See TcSMonad Note [The improvement story and derived shadows]
      
      * Rather than have a separate inert_model in the InertCans, I've
        put the derived equalities back into inert_eqs.  We weren't
        gaining anything from a separate field.
      
      * Previously we had a mode for the constraint solver in which it
        would more aggressively solve Derived constraints; it was used
        for simplifying the context of a 'deriving' clause, or a 'default'
        delcaration, for example.
      
        But the complexity wasn't worth it; now I just make proper Wanted
        constraints.  See TcMType.cloneWC
      
      * Don't generate injectivity improvement for Givens; see
        Note [No FunEq improvement for Givens] in TcInteract
      
      * solveSimpleWanteds leaves the insolubles in-place rather than
        returning them.  Simpler.
      
      I also did lots of work on comments, including fixing Trac #12821.
      1eec1f21
  6. 15 Nov, 2016 1 commit
  7. 13 Nov, 2016 1 commit
    • Ben Gamari's avatar
      Kill Type pretty-printer · 6c0f10fa
      Ben Gamari authored
      Here we consolidate the pretty-printing logic for types in IfaceType. We
      need IfaceType regardless and the printer for Type can be implemented in
      terms of that for IfaceType. See #11660.
      
      Note that this is very much a work-in-progress. Namely I still have yet
      to ponder how to ease the hs-boot file situation, still need to rip out
      more dead code, need to move some of the special cases for, e.g., `*` to
      the IfaceType printer, and need to get it to validate. That being said,
      it comes close to validating as-is.
      
      Test Plan: Validate
      
      Reviewers: goldfire, austin
      
      Subscribers: goldfire, thomie, simonpj
      
      Differential Revision: https://phabricator.haskell.org/D2528
      
      GHC Trac Issues: #11660
      6c0f10fa
  8. 02 Nov, 2016 1 commit
    • Simon Peyton Jones's avatar
      Use substTyUnchecked in TcMType.new_meta_tv_x · f4a14d6c
      Simon Peyton Jones authored
      Sadly, one of the indirect callers of this function doesn't yet
      enforce the in-scope set.  It's in the TcHsType.tc_infer_args swamp,
      so I'm not going to wade in there today.
      
      The assertion tripped when investigating Trac #12785; but this patch
      does NOT fix the actual bug reported there.
      f4a14d6c
  9. 24 Oct, 2016 1 commit
    • Simon Peyton Jones's avatar
      Take account of kinds in promoteTcType · 08ba691a
      Simon Peyton Jones authored
      One of the ASSERT failures in Trac #12762, namely the one for T4439,
      showed that I had not dealt correctly with promoting the kind of
      a type in promoteTcType.
      
      Happily I could fix this by simplifying InferRes (eliminating the
      ir_kind field), so things get better. And the ASSERT is fixed.
      08ba691a
  10. 21 Oct, 2016 1 commit
    • Simon Peyton Jones's avatar
      A collection of type-inference refactorings. · 3f5673f3
      Simon Peyton Jones authored
      This patch does a raft of useful tidy-ups in the type checker.
      I've been meaning to do this for some time, and finally made
      time to do it en route to ICFP.
      
      1. Modify TcType.ExpType to make a distinct data type,
         InferResult for the Infer case, and consequential
         refactoring.
      
      2. Define a new function TcUnify.fillInferResult, to fill in
         an InferResult. It uses TcMType.promoteTcType to promote
         the type to the level of the InferResult.
         See TcMType Note [Promoting a type]
         This refactoring is in preparation for an improvement
         to typechecking pattern bindings, coming next.
      
         I flirted with an elaborate scheme to give better
         higher rank inference, but it was just too complicated.
         See TcMType Note [Promotion and higher rank types]
      
      3. Add to InferResult a new field ir_inst :: Bool to say
         whether or not the type used to fill in the
         InferResult should be deeply instantiated.  See
         TcUnify Note [Deep instantiation of InferResult].
      
      4. Add a TcLevel to SkolemTvs. This will be useful generally
      
          - it's a fast way to see if the type
            variable escapes when floating (not used yet)
      
          - it provides a good consistency check when updating a
            unification variable (TcMType.writeMetaTyVarRef, the
            level_check_ok check)
      
         I originally had another reason (related to the flirting
         in (2), but I left it in because it seems like a step in
         the right direction.
      
      5. Reduce and simplify the plethora of uExpType,
         tcSubType and related functions in TcUnify.  It was
         such an opaque mess and it's still not great, but it's
         better.
      
      6. Simplify the uo_expected field of TypeEqOrigin.  Richard
         had generatlised it to a ExpType, but it was almost always
         a Check type.  Now it's back to being a plain TcType which
         is much, much easier.
      
      7. Improve error messages by refraining from skolemisation when
         it's clear that there's an error: see
         TcUnify Note [Don't skolemise unnecessarily]
      
      8. Type.isPiTy and isForAllTy seem to be missing a coreView check,
         so I added it
      
      9. Kill off tcs_used_tcvs.  Its purpose is to track the
         givens used by wanted constraints.  For dictionaries etc
         we do that via the free vars of the /bindings/ in the
         implication constraint ic_binds.  But for coercions we
         just do update-in-place in the type, rather than
         generating a binding.  So we need something analogous to
         bindings, to track what coercions we have added.
      
         That was the purpose of tcs_used_tcvs.  But it only
         worked for a /single/ iteration, whereas we may have
         multiple iterations of solving an implication.  Look
         at (the old) 'setImplicationStatus'.  If the constraint
         is unsolved, it just drops the used_tvs on the floor.
         If it becomes solved next time round, we'll pick up
         coercions used in that round, but ignore ones used in
         the first round.
      
         There was an outright bug.  Result = (potentialy) bogus
         unused-constraint errors.  Constructing a case where this
         actually happens seems quite trick so I did not do so.
      
         Solution: expand EvBindsVar to include the (free vars of
         the) coercions, so that the coercions are tracked in
         essentially the same way as the bindings.
      
         This turned out to be much simpler.  Less code, more
         correct.
      
      10. Make the ic_binds field in an implication have type
            ic_binds :: EvBindsVar
          instead of (as previously)
             ic_binds :: Maybe EvBindsVar
          This is notably simpler, and faster to use -- less
          testing of the Maybe.  But in the occaional situation
          where we don't have anywhere to put the bindings, the
          belt-and-braces error check is lost.  So I put it back
          as an ASSERT in 'setImplicationStatus' (see the use of
          'termEvidenceAllowed')
      
      All these changes led to quite bit of error message wibbling
      3f5673f3
  11. 15 Jun, 2016 2 commits
    • Simon Peyton Jones's avatar
      Major patch to introduce TyConBinder · e368f326
      Simon Peyton Jones authored
      Before this patch, following the TypeInType innovations,
      each TyCon had two lists:
        - tyConBinders :: [TyBinder]
        - tyConTyVars  :: [TyVar]
      
      They were in 1-1 correspondence and contained
      overlapping information.  More broadly, there were many
      places where we had to pass around this pair of lists,
      instead of a single list.
      
      This commit tidies all that up, by having just one list of
      binders in a TyCon:
      
        - tyConBinders :: [TyConBinder]
      
      The new data types look like this:
      
        Var.hs:
           data TyVarBndr tyvar vis = TvBndr tyvar vis
           data VisibilityFlag = Visible | Specified | Invisible
           type TyVarBinder = TyVarBndr TyVar VisibilityFlag
      
        TyCon.hs:
           type TyConBinder = TyVarBndr TyVar TyConBndrVis
      
           data TyConBndrVis
             = NamedTCB VisibilityFlag
             | AnonTCB
      
        TyCoRep.hs:
           data TyBinder
             = Named TyVarBinder
             | Anon Type
      
      Note that Var.TyVarBdr has moved from TyCoRep and has been
      made polymorphic in the tyvar and visiblity fields:
      ...
      e368f326
    • Simon Peyton Jones's avatar
      Re-add FunTy (big patch) · 77bb0927
      Simon Peyton Jones authored
      With TypeInType Richard combined ForAllTy and FunTy, but that was often
      awkward, and yielded little benefit becuase in practice the two were
      always treated separately.  This patch re-introduces FunTy.  Specfically
      
      * New type
          data TyVarBinder = TvBndr TyVar VisibilityFlag
        This /always/ has a TyVar it.  In many places that's just what
        what we want, so there are /lots/ of TyBinder -> TyVarBinder changes
      
      * TyBinder still exists:
          data TyBinder = Named TyVarBinder | Anon Type
      
      * data Type = ForAllTy TyVarBinder Type
                  | FunTy Type Type
                  |  ....
      
      There are a LOT of knock-on changes, but they are all routine.
      
      The Haddock submodule needs to be updated too
      77bb0927
  12. 13 Jun, 2016 2 commits
    • Simon Peyton Jones's avatar
      Tidy up zonkQuantifiedTyVar · c28dde37
      Simon Peyton Jones authored
      I managed to eliminate the strange zonkQuantifiedTyVarOrType,
      which is no longer used.
      c28dde37
    • Simon Peyton Jones's avatar
      Improve typechecking of let-bindings · 15b9bf4b
      Simon Peyton Jones authored
      This major commit was initially triggered by #11339, but it spiraled
      into a major review of the way in which type signatures for bindings
      are handled, especially partial type signatures.  On the way I fixed a
      number of other bugs, namely
         #12069
         #12033
         #11700
         #11339
         #11670
      
      The main change is that I completely reorganised the way in which type
      signatures in bindings are handled. The new story is in TcSigs
      Note [Overview of type signatures].  Some specific:
      
      * Changes in the data types for signatures in TcRnTypes:
        TcIdSigInfo and new TcIdSigInst
      
      * New module TcSigs deals with typechecking type signatures
        and pragmas. It contains code mostly moved from TcBinds,
        which is already too big
      
      * HsTypes: I swapped the nesting of HsWildCardBndrs
        and HsImplicitBndsrs, so that the wildcards are on the
        oustide not the insidde in a LHsSigWcType.  This is just
        a matter of convenient, nothing deep.
      
      There are a host of other changes as knock-on effects, and
      it all took FAR longer than I anticipated :-).  But it is
      a significant improvement, I think.
      
      Lots of error messages changed slightly, some just variants but
      some modest improvements.
      
      New tests
      
      * typecheck/should_compile
          * SigTyVars: a scoped-tyvar test
          * ExPat, ExPatFail: existential pattern bindings
          * T12069
          * T11700
          * T11339
      
      * partial-sigs/should_compile
          * T12033
          * T11339a
          * T11670
      
      One thing to check:
      
      * Small change to output from ghc-api/landmines.
        Need to check with Alan Zimmerman
      15b9bf4b
  13. 25 May, 2016 1 commit
  14. 12 May, 2016 1 commit
  15. 10 May, 2016 2 commits
  16. 29 Apr, 2016 1 commit
    • eir@cis.upenn.edu's avatar
      Remove the incredibly hairy splitTelescopeTvs. · c5919f75
      eir@cis.upenn.edu authored
      This patch removes splitTelescopeTvs by adding information about
      scoped type variables to TcTyCon. Vast simplification!
      
      This also fixes #11821 by bringing only unzonked vars into scope.
      
      Test case: polykinds/T11821
      c5919f75
  17. 26 Apr, 2016 2 commits
    • niteria's avatar
      Kill varSetElems try_tyvar_defaulting · 94320e1d
      niteria authored
      `varSetElems` introduces unnecessary nondeterminism and we can do
      the same thing deterministically for the same price.
      
      Test Plan: ./validate
      
      Reviewers: goldfire, austin, simonmar, bgamari, simonpj
      
      Reviewed By: simonpj
      
      Subscribers: thomie
      
      Differential Revision: https://phabricator.haskell.org/D2143
      
      GHC Trac Issues: #4012
      94320e1d
    • niteria's avatar
      Kill varSetElemsWellScoped in quantifyTyVars · c9bcaf31
      niteria authored
      varSetElemsWellScoped introduces unnecessary non-determinism in
      inferred type signatures.
      Removing this instance required changing the representation of
      TcDepVars to use deterministic sets.
      This is the last occurence of varSetElemsWellScoped, allowing me to
      finally remove it.
      
      Test Plan:
      ./validate
      I will update the expected outputs when commiting, some reordering
      of type variables in types is expected.
      
      Reviewers: goldfire, simonpj, austin, bgamari
      
      Reviewed By: simonpj
      
      Subscribers: thomie, simonmar
      
      Differential Revision: https://phabricator.haskell.org/D2135
      
      GHC Trac Issues: #4012
      c9bcaf31
  18. 22 Apr, 2016 1 commit
    • Simon Peyton Jones's avatar
      Simplify defaultKindVar and friends · 970ff585
      Simon Peyton Jones authored
      I found zonkQuantifiedTyVar rather complicated, especially the two
      places where we defaulted RuntimeRep variables. This simplifies and
      modularises the story.
      
      Refactoring only.
      970ff585
  19. 19 Apr, 2016 1 commit
    • Simon Peyton Jones's avatar
      Refactor computing dependent type vars · 17eb2419
      Simon Peyton Jones authored
      There should be no change in behaviour here
      
      * Move splitDepVarsOfType(s) from Type to TcType
      
      * Define data type TcType.TcDepVars, document what it means,
        and use it where appropriate, notably in splitDepVarsOfType(s)
      
      * Use it in TcMType.quantifyTyVars and friends
      17eb2419
  20. 31 Mar, 2016 2 commits
  21. 29 Mar, 2016 1 commit
    • niteria's avatar
      Use a correct substitution in tcInstType · 73935326
      niteria authored
      `ty` doesn't have to be a closed type, so we need to add its
      free vars to the in-scope set. They don't seem to be
      available anywhere nearby, so we have to compute them.
      
      Test Plan: ./validate
      
      Reviewers: goldfire, austin, bgamari, simonpj
      
      Reviewed By: simonpj
      
      Subscribers: thomie, simonmar
      
      Differential Revision: https://phabricator.haskell.org/D2042
      
      GHC Trac Issues: #11371
      73935326
  22. 21 Mar, 2016 1 commit
  23. 15 Mar, 2016 2 commits
    • eir@cis.upenn.edu's avatar
      Fix #11648. · 55577a91
      eir@cis.upenn.edu authored
      We now check that a CUSK is really a CUSK and issue an error if
      it isn't. This also involves more solving and zonking in
      kcHsTyVarBndrs, which was the outright bug reported in #11648.
      
      Test cases: polykinds/T11648{,b}
      
      This updates the haddock submodule.
      
      [skip ci]
      55577a91
    • eir@cis.upenn.edu's avatar
      Fix #11334. · 84c773e1
      eir@cis.upenn.edu authored
      Now we fail when trying to default non-*-kinded kind variables
      with -XNoPolyKinds.
      
      test case: dependent/should_fail/T11334
      
      [skip ci]
      84c773e1
  24. 24 Feb, 2016 1 commit
    • eir@cis.upenn.edu's avatar
      Address #11471 by putting RuntimeRep in kinds. · d8c64e86
      eir@cis.upenn.edu authored
      See Note [TYPE] in TysPrim. There are still some outstanding
      pieces in #11471 though, so this doesn't actually nail the bug.
      
      This commit also contains a few performance improvements:
      
      * Short-cut equality checking of nullary type syns
      
      * Compare types before kinds in eqType
      
      * INLINE coreViewOneStarKind
      
      * Store tycon binders separately from kinds.
      
      This resulted in a ~10% performance improvement in compiling
      the Cabal package. No change in functionality other than
      performance. (This affects the interface file format, though.)
      
      This commit updates the haddock submodule.
      d8c64e86
  25. 18 Feb, 2016 1 commit
    • Simon Peyton Jones's avatar
      (Another) minor refactoring of substitutions · b5292557
      Simon Peyton Jones authored
      No change in functionality here, but greater clarity:
      
      * In FamInstEnv.FlattenEnv, kill off the fi_in_scope field
        We are already maintaining an in-scope set in the fe_subst field,
        so it's silly do to it twice.
      
        (This isn't strictly connected to the rest of this patch, but
        the nomenclature changes below affect the same code, so I put
        them together.)
      
      * TyCoRep.extendTCVSubst used to take a TyVar or a CoVar and work
        out what to do, but in fact we almost always know which of the
        two we are doing.  So:
          - define extendTvSubst, extendCvSubst
          - and use them
      
      * Similar renamings in TyCoRep:
         - extendTCvSubstList        -->   extendTvSubstList
         - extendTCvSubstBinder      -->   extendTvSubstBinder
         - extendTCvSubstAndInScope  --> extendTvSubstAndInScope
      
      * Add Type.extendTvSubstWithClone, extendCvSubstWithClone
      
      * Similar nomenclature changes in Subst, SimplEnv, Specialise
      
      * Kill off TyCoRep.substTelescope (never used)
      b5292557
  26. 17 Feb, 2016 1 commit
    • eir@cis.upenn.edu's avatar
      Fix #11313. · a6152159
      eir@cis.upenn.edu authored
      Previously, we looked through synonyms when counting arguments,
      but that's a bit silly.
      a6152159
  27. 12 Feb, 2016 1 commit
  28. 08 Feb, 2016 1 commit
  29. 02 Feb, 2016 1 commit
    • Ben Gamari's avatar
      TcMType: Add some elementary notes · 871c96f1
      Ben Gamari authored
      It's astoundingly difficult to find a good description of zonking. Given
      that there is a Stack Overflow question on the matter, I'm clearly not
      the only one who feels this way. Hopefully this will clarify the issue.
      
      Test Plan: Read it
      
      Reviewers: goldfire, austin, simonpj
      
      Subscribers: thomie
      
      Differential Revision: https://phabricator.haskell.org/D1859
      871c96f1
  30. 27 Jan, 2016 2 commits
    • eir@cis.upenn.edu's avatar
      Refactor the typechecker to use ExpTypes. · 00cbbab3
      eir@cis.upenn.edu authored
      The idea here is described in [wiki:Typechecker]. Briefly,
      this refactor keeps solid track of "synthesis" mode vs
      "checking" in GHC's bidirectional type-checking algorithm.
      When in synthesis mode, the expected type is just an IORef
      to write to.
      
      In addition, this patch does a significant reworking of
      RebindableSyntax, allowing much more freedom in the types
      of the rebindable operators. For example, we can now have
      `negate :: Int -> Bool` and
      `(>>=) :: m a -> (forall x. a x -> m b) -> m b`. The magic
      is in tcSyntaxOp.
      
      This addresses tickets #11397, #11452, and #11458.
      
      Tests:
        typecheck/should_compile/{RebindHR,RebindNegate,T11397,T11458}
        th/T11452
      00cbbab3
    • eir@cis.upenn.edu's avatar
      Fix some substitution InScopeSets · 2899aa58
      eir@cis.upenn.edu authored
      This is relevant to #11371.
      2899aa58
  31. 26 Jan, 2016 1 commit
    • niteria's avatar
      Construct in_scope set in mkTopTCvSubst · 144ddb41
      niteria authored
      The pre-condition on `mkTopTCvSubst` turned out to be wrong and
      not satisfied by any of the callers. I've fixed it, so that it
      constructs the in_scope set from the range of the substitution.
      `mkTopTCvSubst` was also unnecessarily general it is never called
      with `CoVars`, so I changed the type signature and added an assertion.
      
      Test Plan: ./validate --slow
      
      Reviewers: goldfire, simonpj, bgamari, austin
      
      Reviewed By: simonpj
      
      Subscribers: thomie
      
      Differential Revision: https://phabricator.haskell.org/D1801
      
      GHC Trac Issues: #11371
      144ddb41
  32. 19 Jan, 2016 1 commit
    • niteria's avatar
      Check InScopeSet in substTy and provide substTyUnchecked · 9d33adb6
      niteria authored
      This adds sanity checks to `substTy` that implement:
      
      > when calling substTy subst ty it should be the case that the in-scope
      > set in the substitution is a superset of
      > * The free vars of the range of the substitution
      > * The free vars of ty minus the domain of the substitution
      
      and replaces violators with unchecked version. The violators were found
      by running the GHC test suite.
      
      This ensures that I can work on this incrementally and that what I fix won't
      be undone by some other change.
      
      It also includes a couple of fixes that I've already done.
      
      Test Plan: ./validate
      
      Reviewers: simonmar, goldfire, simonpj, austin, bgamari
      
      Reviewed By: simonpj, bgamari
      
      Subscribers: thomie
      
      Differential Revision: https://phabricator.haskell.org/D1792
      
      GHC Trac Issues: #11371
      9d33adb6