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* Improve handling of data type return kindswip/T18300Simon Peyton Jones2020-07-031-0/+0
| | | | | | | | | | | | | | | | | | Following a long conversation with Richard, this patch tidies up the handling of return kinds for data/newtype declarations (vanilla, family, and instance). I have substantially edited the Notes in TyCl, so they would bear careful reading. Fixes #18300, #18357 In GHC.Tc.Instance.Family.newFamInst we were checking some Lint-like properties with ASSSERT. Instead Richard and I have added a proper linter for axioms, and called it from lintGblEnv, which in turn is called in tcRnModuleTcRnM New tests (T18300, T18357) cause an ASSERT failure in HEAD.
* core-spec: Modify file paths according to new module hierarchyTakenobu Tani2020-05-271-0/+0
| | | | | | | | | | | | | | | | | | | | | | | This patch updates file paths according to new module hierarchy [1]: * GHC/Core.hs <= coreSyn/CoreSyn.hs * GHC/Core/Coercion.hs <= types/Coercion.hs * GHC/Core/Coercion/Axiom.hs <= types/CoAxiom.hs * GHC/Core/Coercion/Opt.hs <= types/OptCoercion.hs * GHC/Core/DataCon.hs <= basicTypes/DataCon.hs * GHC/Core/FamInstEnv.hs <= types/FamInstEnv.hs * GHC/Core/Lint.hs <= coreSyn/CoreLint.hs * GHC/Core/Subst.hs <= coreSyn/CoreSubst.hs * GHC/Core/TyCo/Rep.hs <= types/TyCoRep.hs * GHC/Core/TyCon.hs <= types/TyCon.hs * GHC/Core/Type.hs <= types/Type.hs * GHC/Core/Unify.hs <= types/Unify.hs * GHC/Types/Literal.hs <= basicTypes/Literal.hs * GHC/Types/Var.hs <= basicTypes/Var.hs [1]: https://gitlab.haskell.org/ghc/ghc/-/wikis/Make-GHC-codebase-more-modular [skip ci]
* Update core spec to reflect changes to Core.Richard Eisenberg2020-03-201-0/+0
| | | | | | | | | | | | Key changes: * Adds a new rule for forall-coercions over coercion variables, which was implemented but conspicuously missing from the spec. * Adds treatment for FunCo. * Adds treatment for ForAllTy over coercion variables. * Improves commentary (including restoring a Note lost in 03d4852658e1b7407abb4da84b1b03bfa6f6db3b) in the source. No changes to running code.
* core-spec: Modify `.lhs` to `.hs` (generated PDF)Takenobu Tani2019-01-021-0/+0
| | | | | | | | Modify old filename `.lhs` to `.hs` in following file: * docs/core-spec/core-spec.pdf (generated PDF) [ci skip]
* Update core-spec for Coercion QuantificationNingning Xie2018-10-251-0/+0
| | | | | | | | | | | | | | | | | | Summary: Update details for `ForAllTy` and `ForAllCo` in core-spec, as they can now quantify over coercion variables. Test Plan: Please read core-spec.pdf Reviewers: goldfire, simonpj, bgamari Reviewed By: goldfire Subscribers: rwbarton, carter GHC Trac Issues: #15497, #15589 Differential Revision: https://phabricator.haskell.org/D5247
* update core-spec for GRefl and re-factored Reflningning2018-07-271-0/+0
| | | | | | | | | | | | | | | | | Ticket #15192 introduced the generalized reflexive coercion `GRefl` and nominal reflexive `Refl`, and removed `CoherenceCo`. Update core-spec accordingly. Not sure about notations though; suggestions on more concise notations would be great. Test Plan: Read core-spec.pdf Reviewers: goldfire, bgamari Reviewed By: goldfire Subscribers: rwbarton, thomie, carter Differential Revision: https://phabricator.haskell.org/D4984
* Modernize S_TPush in the core specRyan Scott2018-07-161-0/+0
| | | | | | | | | | | | | | | | | Summary: The specification for the `S_TPush` rule in the core spec's operational semantics is woefully out-of-date. Let's bring it in line with the presentation in //System FC with Explicit Kind Equality//. Test Plan: Read it Reviewers: goldfire, bgamari Reviewed By: goldfire Subscribers: rwbarton, thomie, carter Differential Revision: https://phabricator.haskell.org/D4970
* Fix parse errors in core-spec.pdfRyan Scott2018-07-161-0/+0
| | | | | | | | | | | | | | | | | | | | Summary: `core-spec.pdf` was emitting parse errors due to not specifying role arguments in some uses of `nth`. This patch adds those role arguments. (Credit goes to Richard Eisenberg for actually figuring out what said arguments should be.) Test Plan: Read it Reviewers: goldfire, bgamari Reviewed By: goldfire Subscribers: rwbarton, thomie, carter GHC Trac Issues: #15373 Differential Revision: https://phabricator.haskell.org/D4965
* The Types section in Core-Spec doc is out-datedningning2018-07-121-0/+0
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* Caching coercion roles in NthCo and coercionKindsRole refactoringTobias Dammers2018-04-201-0/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | While addressing nonlinear behavior related to coercion roles, particularly `NthCo`, we noticed that coercion roles are recalculated often even though they should be readily at hand already in most cases. This patch adds a `Role` to the `NthCo` constructor so that we can cache them rather than having to recalculate them on the fly. https://ghc.haskell.org/trac/ghc/ticket/11735#comment:23 explains the approach. Performance improvement over GHC HEAD, when compiling Grammar.hs (see below): GHC 8.2.1: ``` ghc Grammar.hs 176.27s user 0.23s system 99% cpu 2:56.81 total ``` before patch (but with other optimizations applied): ``` ghc Grammar.hs -fforce-recomp 175.77s user 0.19s system 100% cpu 2:55.78 total ``` after: ``` ../../ghc/inplace/bin/ghc-stage2 Grammar.hs 10.32s user 0.17s system 98% cpu 10.678 total ``` Introduces the following regressions: - perf/compiler/parsing001 (possibly false positive) - perf/compiler/T9872 - perf/compiler/haddock.base Reviewers: goldfire, bgamari, simonpj Reviewed By: simonpj Subscribers: rwbarton, thomie, carter GHC Trac Issues: #11735 Differential Revision: https://phabricator.haskell.org/D4394
* core-spec: Add join points to formalismLuke Maurer2017-10-301-0/+0
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* core-spec: Simplify the handling of LetRecJoachim Breitner2017-04-241-0/+0
| | | | | | | | | | | | We do not need to keep an enrivonment around to implement letrec, as long as we only do call-by-name. Instead, evaluate letrec by substituting for all the variables with their RHS wrapped in the letrec binding. Since nothing adds to the enrivonment any more, there is no need for a S_Var rule. Differential Revision: https://phabricator.haskell.org/D3466
* Fix LaTeX in core-specJoachim Breitner2017-04-181-0/+0
| | | | | where d49b2bb21691892ca6ac8f2403e31f2a5e53feb3 introduced some TeX breakage, and re-generate core-spec.pdf.
* core-spec: Fix S_MatchDataJoachim Breitner2016-12-021-0/+0
| | | | | Previously, it would substitute e for n without an e being around. I clarify that by naming the scrutinee e.
* Add kind equalities to GHC.Richard Eisenberg2015-12-111-0/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This implements the ideas originally put forward in "System FC with Explicit Kind Equality" (ICFP'13). There are several noteworthy changes with this patch: * We now have casts in types. These change the kind of a type. See new constructor `CastTy`. * All types and all constructors can be promoted. This includes GADT constructors. GADT pattern matches take place in type family equations. In Core, types can now be applied to coercions via the `CoercionTy` constructor. * Coercions can now be heterogeneous, relating types of different kinds. A coercion proving `t1 :: k1 ~ t2 :: k2` proves both that `t1` and `t2` are the same and also that `k1` and `k2` are the same. * The `Coercion` type has been significantly enhanced. The documentation in `docs/core-spec/core-spec.pdf` reflects the new reality. * The type of `*` is now `*`. No more `BOX`. * Users can write explicit kind variables in their code, anywhere they can write type variables. For backward compatibility, automatic inference of kind-variable binding is still permitted. * The new extension `TypeInType` turns on the new user-facing features. * Type families and synonyms are now promoted to kinds. This causes trouble with parsing `*`, leading to the somewhat awkward new `HsAppsTy` constructor for `HsType`. This is dispatched with in the renamer, where the kind `*` can be told apart from a type-level multiplication operator. Without `-XTypeInType` the old behavior persists. With `-XTypeInType`, you need to import `Data.Kind` to get `*`, also known as `Type`. * The kind-checking algorithms in TcHsType have been significantly rewritten to allow for enhanced kinds. * The new features are still quite experimental and may be in flux. * TODO: Several open tickets: #11195, #11196, #11197, #11198, #11203. * TODO: Update user manual. Tickets addressed: #9017, #9173, #7961, #10524, #8566, #11142. Updates Haddock submodule.
* Fix the formal operational semantics (#10121)Richard Eisenberg2015-04-241-0/+0
| | | | | This adapts the work of Christiaan Baaij to present a sensible operational semantics for FC with mutual recursion.
* Improve core linter so it catches unsafeCoerce problems (T9122)Alexander Vershilov2015-03-071-0/+0
| | | | | | | | | | | | | | | | | | | | | | | Summary: This is a draft of the patch that is sent for review. In this patch required changes in linter were introduced and actual check: - new helper function: primRepSizeB - primRep check for floating - Add access to dynamic flags in linter. - Implement additional lint rules. Reviewers: austin, goldfire, simonpj Reviewed By: simonpj Subscribers: thomie Differential Revision: https://phabricator.haskell.org/D637 GHC Trac Issues: #9122
* Fix formatting bug in core-spec.Richard Eisenberg2014-09-181-0/+0
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* Fix glitch in core-spec pdfJan Stolarek2014-01-291-0/+0
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* Regenerate core-spec.pdf.Richard Eisenberg2014-01-131-0/+0
| | | | | This applies the changes in commit a924debcbb3dc5c004f988fcc1b480a01ba276dd to the PDF file.
* Update to core-spec documentation.Richard Eisenberg2013-11-251-0/+0
| | | | | This update includes some wibbles to make Co_TyConAppCo clearer, as well as the introduction of forms for AxiomRuleCo.
* Clarification in formalism concerning roles.Richard Eisenberg2013-09-091-0/+0
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* Fix Trac #8138.Richard Eisenberg2013-08-161-0/+0
| | | | | | | | The code in CoreLint did not take into account the possibility of ~R# arguments to functions. These can arise in argToPat in SpecConstr. Now, CoreLint does not fail when it sees a ~R# parameter. This commit also updates the core-spec document accordingly.
* Implement "roles" into GHC.Richard Eisenberg2013-08-021-0/+0
| | | | | | | | | | | | | | | | Roles are a solution to the GeneralizedNewtypeDeriving type-safety problem. Roles were first described in the "Generative type abstraction" paper, by Stephanie Weirich, Dimitrios Vytiniotis, Simon PJ, and Steve Zdancewic. The implementation is a little different than that paper. For a quick primer, check out Note [Roles] in Coercion. Also see http://ghc.haskell.org/trac/ghc/wiki/Roles and http://ghc.haskell.org/trac/ghc/wiki/RolesImplementation For a more formal treatment, check out docs/core-spec/core-spec.pdf. This fixes Trac #1496, #4846, #7148.
* Fix Trac #8020.Richard Eisenberg2013-08-021-0/+0
| | | | | | | The solution is to use a different notion of apartness. See http://research.microsoft.com/en-us/um/people/simonpj/papers/ext-f/axioms-extended.pdf for the gory details. Some comments are also in Notes [Compatibility] and [Apartness] in FamInstEnv.
* Added operational semantics to docs/core-spec.Richard Eisenberg2013-07-311-0/+0
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* Revise implementation of overlapping type family instances.Richard Eisenberg2013-06-211-0/+0
| | | | | | | | | | | | | | | | | | | This commit changes the syntax and story around overlapping type family instances. Before, we had "unbranched" instances and "branched" instances. Now, we have closed type families and open ones. The behavior of open families is completely unchanged. In particular, coincident overlap of open type family instances still works, despite emails to the contrary. A closed type family is declared like this: > type family F a where > F Int = Bool > F a = Char The equations are tried in order, from top to bottom, subject to certain constraints, as described in the user manual. It is not allowed to declare an instance of a closed family.
* Implement overlapping type family instances.Richard Eisenberg2012-12-211-0/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | An ordered, overlapping type family instance is introduced by 'type instance where', followed by equations. See the new section in the user manual (7.7.2.2) for details. The canonical example is Boolean equality at the type level: type family Equals (a :: k) (b :: k) :: Bool type instance where Equals a a = True Equals a b = False A branched family instance, such as this one, checks its equations in order and applies only the first the matches. As explained in the note [Instance checking within groups] in FamInstEnv.lhs, we must be careful not to simplify, say, (Equals Int b) to False, because b might later unify with Int. This commit includes all of the commits on the overlapping-tyfams branch. SPJ requested that I combine all my commits over the past several months into one monolithic commit. The following GHC repos are affected: ghc, testsuite, utils/haddock, libraries/template-haskell, and libraries/dph. Here are some details for the interested: - The definition of CoAxiom has been moved from TyCon.lhs to a new file CoAxiom.lhs. I made this decision because of the number of definitions necessary to support BranchList. - BranchList is a GADT whose type tracks whether it is a singleton list or not-necessarily-a-singleton-list. The reason I introduced this type is to increase static checking of places where GHC code assumes that a FamInst or CoAxiom is indeed a singleton. This assumption takes place roughly 10 times throughout the code. I was worried that a future change to GHC would invalidate the assumption, and GHC might subtly fail to do the right thing. By explicitly labeling CoAxioms and FamInsts as being Unbranched (singleton) or Branched (not-necessarily-singleton), we make this assumption explicit and checkable. Furthermore, to enforce the accuracy of this label, the list of branches of a CoAxiom or FamInst is stored using a BranchList, whose constructors constrain its type index appropriately. I think that the decision to use BranchList is probably the most controversial decision I made from a code design point of view. Although I provide conversions to/from ordinary lists, it is more efficient to use the brList... functions provided in CoAxiom than always to convert. The use of these functions does not wander far from the core CoAxiom/FamInst logic. BranchLists are motivated and explained in the note [Branched axioms] in CoAxiom.lhs. - The CoAxiom type has changed significantly. You can see the new type in CoAxiom.lhs. It uses a CoAxBranch type to track branches of the CoAxiom. Correspondingly various functions producing and consuming CoAxioms had to change, including the binary layout of interface files. - To get branched axioms to work correctly, it is important to have a notion of type "apartness": two types are apart if they cannot unify, and no substitution of variables can ever get them to unify, even after type family simplification. (This is different than the normal failure to unify because of the type family bit.) This notion in encoded in tcApartTys, in Unify.lhs. Because apartness is finer-grained than unification, the tcUnifyTys now calls tcApartTys. - CoreLinting axioms has been updated, both to reflect the new form of CoAxiom and to enforce the apartness rules of branch application. The formalization of the new rules is in docs/core-spec/core-spec.pdf. - The FamInst type (in types/FamInstEnv.lhs) has changed significantly, paralleling the changes to CoAxiom. Of course, this forced minor changes in many files. - There are several new Notes in FamInstEnv.lhs, including one discussing confluent overlap and why we're not doing it. - lookupFamInstEnv, lookupFamInstEnvConflicts, and lookup_fam_inst_env' (the function that actually does the work) have all been more-or-less completely rewritten. There is a Note [lookup_fam_inst_env' implementation] describing the implementation. One of the changes that affects other files is to change the type of matches from a pair of (FamInst, [Type]) to a new datatype (which now includes the index of the matching branch). This seemed a better design. - The TySynInstD constructor in Template Haskell was updated to use the new datatype TySynEqn. I also bumped the TH version number, requiring changes to DPH cabal files. (That's why the DPH repo has an overlapping-tyfams branch.) - As SPJ requested, I refactored some of the code in HsDecls: * splitting up TyDecl into SynDecl and DataDecl, correspondingly changing HsTyDefn to HsDataDefn (with only one constructor) * splitting FamInstD into TyFamInstD and DataFamInstD and splitting FamInstDecl into DataFamInstDecl and TyFamInstDecl * making the ClsInstD take a ClsInstDecl, for parallelism with InstDecl's other constructors * changing constructor TyFamily into FamDecl * creating a FamilyDecl type that stores the details for a family declaration; this is useful because FamilyDecls can appear in classes but other decls cannot * restricting the associated types and associated type defaults for a * class to be the new, more restrictive types * splitting cid_fam_insts into cid_tyfam_insts and cid_datafam_insts, according to the new types * perhaps one or two more that I'm overlooking None of these changes has far-reaching implications. - The user manual, section 7.7.2.2, is updated to describe the new type family instances.
* Added GHC formalism to the GHC source tree.Richard Eisenberg2012-12-011-0/+0
As per a request from Simon PJ, I wrote up a formalism of the core language in GHC, System FC. The writeup lives in docs/core-spec. I also added comments to a number of files dealing with the core language reminding authors to update the formalism when updating the code. In the next commit will be a README file in docs/core-spec with more details of how to do this.
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