- Mar 20, 2013
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Gabor Greif authored
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- Feb 19, 2013
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Ian Lynagh authored
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- Feb 02, 2013
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Gabor Greif authored
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- Dec 22, 2012
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Richard Eisenberg authored
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.
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- Nov 30, 2012
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Ian Lynagh authored
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Ian Lynagh authored
We now keep the HEAD version numbers as values which would be suitable for immediate release.
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Ian Lynagh authored
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- Sep 18, 2012
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Simon Peyton Jones authored
There were two cases in which we called error * An InfixE with an operator epxression other than VarE or ConE * A comprehension with empty Stmts, ie CompE [] Crashing doesn't help much. Now the library puts in the pretty printed output a textual signal about what went wrong. This addresses the crash in Trac #7235, although doesn't fix the underlying cause, which remains shrouded in obscurity.
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- Aug 15, 2012
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mikhail.vorozhtsov authored
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- Jul 19, 2012
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pcapriotti authored
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- Jul 16, 2012
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Simon Peyton Jones authored
Thanks to Reiner Pope
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Simon Peyton Jones authored
...and deprecate plain 'report', which takes a Boolean flag whose sense is hard to remember. Thanks to Reiner Pope.
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Simon Peyton Jones authored
It didn't contain much, and the approved import route is Language.Haskell.TH, so in effect the Syntax module is already an internal one. Thanks to Reiner Pope.
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Simon Peyton Jones authored
Thanks to Reiner Pope for doing this
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- Jun 19, 2012
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pcapriotti authored
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- Jun 12, 2012
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Simon Marlow authored
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- May 22, 2012
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Ian Lynagh authored
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- May 18, 2012
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Simon Peyton Jones authored
The big change here is that Kind is no longer a distinct type, it's just a type synonym for Type. This reflects exactly what happens in the HsSyn world, and avoids a great deal of duplication between types and kinds. But it is a breaking for (the few) TH users who were using the constructors for Kind. Thanks to lunaris and Richard Eisenberg for doing the work.
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Simon Peyton Jones authored
Thanks to mikhail.vorozhtsov for doing the work
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- Mar 15, 2012
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Iavor S. Diatchki authored
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- Mar 14, 2012
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Simon Peyton Jones authored
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- Mar 06, 2012
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pcapriotti authored
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- Feb 08, 2012
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Ian Lynagh authored
Conal Elliott reported that dataToExpQ built a different constructor for () than [| () |]. This patch fixes that, and adds a regression test.
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- Jan 31, 2012
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Ian Lynagh authored
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- Nov 09, 2011
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Geoffrey Mainland authored
Use tyConPackage and tyConModule to determine the package and module to which a data type belongs. With this information we can use mkNameG_d to build constructor names which ensures that dataToQa creates TH terms that are independent of the set of in-scope names.
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- Nov 05, 2011
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GregWeber authored
Let GHC know about an external dependency that Template Haskell uses so that GHC can recompile when the dependency changes. No support for ghc -M
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- Aug 26, 2011
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Ian Lynagh authored
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- Aug 23, 2011
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Simon Peyton Jones authored
This patch (and its GHC counterpart) implements Trac #4429 (lookupTypeName, lookupValueName) Trac #5406 (reification of type/data family instances) See detailed discussion in those tickets. TH.ClassInstance is no more; instead reifyInstances returns a [Dec], which requires fewer data types and natuarally accommodates family instances. 'reify' on a type/data family now returns 'FamilyI', a new data constructor in 'Info'
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- Aug 20, 2011
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David Terei authored
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- Aug 17, 2011
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Simon Peyton Jones authored
Fixes Trac #5409
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- Aug 10, 2011
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David Terei authored
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- Jul 29, 2011
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Simon Peyton Jones authored
Thanks to Bas van Dijk for proposing this. In the end I replaced Functor by Applicative in the superclasses of Quasi, thus: class (Monad m, Applicative m) => Quasi m where because Functor is a superclass of Applicative.
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- Jul 25, 2011
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reinerp authored
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- Jul 18, 2011
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Simon Peyton Jones authored
The extension is nice, because it just adds an extra constructor to the existing data type 'Strict'. Thanks to Mikhail Vorozhtsov.
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- Jul 12, 2011
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Ian Lynagh authored
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- Jul 06, 2011
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Ian Lynagh authored
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- Jun 21, 2011
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Iavor S. Diatchki authored
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