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* De-tabify and remove trailing whitespaceSimon Peyton Jones2014-09-261-177/+171
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* Typos in commentsGabor Greif2014-08-291-1/+1
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* Refactor unfoldingsSimon Peyton Jones2014-08-281-14/+10
| | | | | | | | | | | | | | | | | | | | There are two main refactorings here 1. Move the uf_arity field out of CoreUnfolding into UnfWhen It's a lot tidier there. If I've got this right, no behaviour should change. 2. Define specUnfolding and use it in DsBinds and Specialise a) commons-up some shared code b) makes sure that Specialise correctly specialises DFun unfoldings (which it didn't before) The two got put together because both ended up interacting in the specialiser. They cause zero difference to nofib.
* Fix-up to d4d4bef2 'Improve the desugaring of RULES'Simon Peyton Jones2014-08-011-2/+8
| | | | | I'd forgotten the possiblity that desugaring could generate dead dictionary bindings; easily fixed by calling occurAnalyseExpr
* Improve the desugaring of RULES, esp those from SPECIALISE pragmasSimon Peyton Jones2014-08-011-11/+64
| | | | | | | | | | | | In the code for Trac #8331 we were not getting a complaint, but we *were* getting a terrible (and virtually useless) RULE, looking like useAbstractMonad (complicated-dictionary-expresion) = $fuseAbstractMonad where we wanted useAbstractMonad d = $fuseAbstractMonad This commit improves the desugaring algorithm. More comments explain; see Note [Drop dictionary bindings on rule LHS]
* Add LANGUAGE pragmas to compiler/ source filesHerbert Valerio Riedel2014-05-151-1/+2
| | | | | | | | | | | | | | | | | | In some cases, the layout of the LANGUAGE/OPTIONS_GHC lines has been reorganized, while following the convention, to - place `{-# LANGUAGE #-}` pragmas at the top of the source file, before any `{-# OPTIONS_GHC #-}`-lines. - Moreover, if the list of language extensions fit into a single `{-# LANGUAGE ... -#}`-line (shorter than 80 characters), keep it on one line. Otherwise split into `{-# LANGUAGE ... -#}`-lines for each individual language extension. In both cases, try to keep the enumeration alphabetically ordered. (The latter layout is preferable as it's more diff-friendly) While at it, this also replaces obsolete `{-# OPTIONS ... #-}` pragma occurences by `{-# OPTIONS_GHC ... #-}` pragmas.
* Instead of tracking Origin in LHsBindsLR, track it in MatchGroupDr. ERDI Gergo2014-04-131-7/+2
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* Improve the desugaring of RULE left-hand-sides (fixes Trac #8848)Simon Peyton Jones2014-03-251-52/+97
| | | | | | | | | | | | | | | | | I've added detailed comments with Note [Decomposing the left-hand side of a RULE] The result is a noticeable improvement. Previously * we rejected a perfectly decent SPECIALISE (Trac #8848) * and for something like f :: (Eq a) => b -> a -> a {-# SPECIALISE f :: b -> [Int] -> [Int] #-} we ended up with RULE f ($fdEqList $dfEqInt) = f_spec whereas we wanted RULES forall (d:Eq [Int]). f d = f_spec
* A bit more tracing to do with SPECIALISE pragmasSimon Peyton Jones2014-03-131-5/+5
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* Implement pattern synonymsDr. ERDI Gergo2014-01-201-3/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch implements Pattern Synonyms (enabled by -XPatternSynonyms), allowing y ou to assign names to a pattern and abstract over it. The rundown is this: * Named patterns are introduced by the new 'pattern' keyword, and can be either *unidirectional* or *bidirectional*. A unidirectional pattern is, in the simplest sense, simply an 'alias' for a pattern, where the LHS may mention variables to occur in the RHS. A bidirectional pattern synonym occurs when a pattern may also be used in expression context. * Unidirectional patterns are declared like thus: pattern P x <- x:_ The synonym 'P' may only occur in a pattern context: foo :: [Int] -> Maybe Int foo (P x) = Just x foo _ = Nothing * Bidirectional patterns are declared like thus: pattern P x y = [x, y] Here, P may not only occur as a pattern, but also as an expression when given values for 'x' and 'y', i.e. bar :: Int -> [Int] bar x = P x 10 * Patterns can't yet have their own type signatures; signatures are inferred. * Pattern synonyms may not be recursive, c.f. type synonyms. * Pattern synonyms are also exported/imported using the 'pattern' keyword in an import/export decl, i.e. module Foo (pattern Bar) where ... Note that pattern synonyms share the namespace of constructors, so this disambiguation is required as a there may also be a 'Bar' type in scope as well as the 'Bar' pattern. * The semantics of a pattern synonym differ slightly from a typical pattern: when using a synonym, the pattern itself is matched, followed by all the arguments. This means that the strictness differs slightly: pattern P x y <- [x, y] f (P True True) = True f _ = False g [True, True] = True g _ = False In the example, while `g (False:undefined)` evaluates to False, `f (False:undefined)` results in undefined as both `x` and `y` arguments are matched to `True`. For more information, see the wiki: https://ghc.haskell.org/trac/ghc/wiki/PatternSynonyms https://ghc.haskell.org/trac/ghc/wiki/PatternSynonyms/Implementation Reviewed-by: Simon Peyton Jones <simonpj@microsoft.com> Signed-off-by: Austin Seipp <austin@well-typed.com>
* Remove dead code orphaned by implementing GND with `coerce`.Richard Eisenberg2013-12-021-3/+0
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* Remove whitespace between macro identifiers and `(`Herbert Valerio Riedel2013-11-291-1/+1
| | | | | | | | This is a kludge to workaround Clang's CPP lacking traditional-mode CPP (This was reported by Kazu Yamamoto) Signed-off-by: Herbert Valerio Riedel <hvr@gnu.org>
* EvCast needs to take a representational coercionJoachim Breitner2013-11-281-1/+1
| | | | as the coercions for type literals are of that role.
* Get rid of EvCoercibleJoachim Breitner2013-11-271-44/+1
| | | | and use EvCoercion to describe the evidence for Coercible instances.
* Roleify TcCoercionJoachim Breitner2013-11-271-44/+42
| | | | | | | | | | | | Previously, TcCoercion were only used to represent boxed Nominal coercions. In order to also talk about boxed Representational coercions in the type checker, we add Roles to TcCoercion. Again, we closely mirror Coercion. The roles are verified by a few assertions, and at the latest after conversion to Coercion. I have put my trust in the comprehensiveness of the testsuite here, but any role error after desugaring popping up now might be caused by this refactoring.
* Extend Coercible to newtype instancesJoachim Breitner2013-11-221-6/+6
| | | | This fixes: #8548
* Make Coercible higher-kindedJoachim Breitner2013-11-201-1/+1
| | | | | | This implements #8541. The changes are fully straight forward and work nicely for the examples from the ticket; this is mostly due to the existing code not checking for saturation and kindness.
* Placate clang (#8444, #8445)Austin Seipp2013-10-251-1/+1
| | | | | | | | Once again the whitespace rules (and the rules concerning expansion of tokens) have bitten us. Authored-by: Authored-by: Luke Iannini <lukexi@me.com> Signed-off-by: Austin Seipp <austin@well-typed.com>
* Remove debugging printouts -- sorry!Richard Eisenberg2013-10-231-7/+2
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* Change GeneralizedNewtypeDeriving safety check.Richard Eisenberg2013-10-231-3/+10
| | | | | | | | | Now, instead of looking at a class's roles, the GND check looks at all of the methods in the class individually. This has the advantage that sometimes, we can use information about the derivation requested during the safety check. For example, we can now derive (IArray UArray), whereas the previous check prevented this.
* Comments onlyunknown2013-10-011-4/+4
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* Globally replace "hackage.haskell.org" with "ghc.haskell.org"Simon Marlow2013-10-011-1/+1
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* Introduce coerce :: Coercible a b -> a -> bcoercibleJoachim Breitner2013-09-131-2/+45
| | | | | | | | | | | This is the result of the design at http://ghc.haskell.org/trac/ghc/wiki/NewtypeWrappers The goal is to be able to convert between, say [First Int] and [Last Int] with zero run-time overhead. To that end, we introduce a special two parameter type class Coercible whose instances are created automatically and on-the fly. This relies on and exploits the recent addition of roles to core.
* Add support for evaluation of type-level natural numbers.Iavor S. Diatchki2013-09-121-0/+5
| | | | | | | | | | | | | | | | | | | | | | | | | This patch implements some simple evaluation of type-level expressions featuring natural numbers. We can evaluate *concrete* expressions that use the built-in type families (+), (*), (^), and (<=?), declared in GHC.TypeLits. We can also do some type inference involving these functions. For example, if we encounter a constraint such as `(2 + x) ~ 5` we can infer that `x` must be 3. Note, however, this is used only to resolve unification variables (i.e., as a form of a constraint improvement) and not to generate new facts. This is similar to how functional dependencies work in GHC. The patch adds a new form of coercion, `AxiomRuleCo`, which makes use of a new form of axiom called `CoAxiomRule`. This is the form of evidence generate when we solve a constraint, such as `(1 + 2) ~ 3`. The patch also adds support for built-in type-families, by adding a new form of TyCon rhs: `BuiltInSynFamTyCon`. such built-in type-family constructors contain a record with functions that are used by the constraint solver to simplify and improve constraints involving the built-in function (see `TcInteract`). The record in defined in `FamInst`. The type constructors and rules for evaluating the type-level functions are in a new module called `TcTypeNats`.
* Implement "roles" into GHC.Richard Eisenberg2013-08-021-26/+33
| | | | | | | | | | | | | | | | 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.
* Make 'SPECIALISE instance' work againSimon Peyton Jones2013-05-301-21/+18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This is a long-standing regression (Trac #7797), which meant that in particular the Eq [Char] instance does not get specialised. (The *methods* do, but the dictionary itself doesn't.) So when you call a function f :: Eq a => blah on a string type (ie a=[Char]), 7.6 passes a dictionary of un-specialised methods. This only matters when calling an overloaded function from a specialised context, but that does matter in some programs. I remember (though I cannot find the details) that Nick Frisby discovered this to be the source of some pretty solid performanc regresisons. Anyway it works now. The key change is that a DFunUnfolding now takes a form that is both simpler than before (the DFunArg type is eliminated) and more general: data Unfolding = ... | DFunUnfolding { -- The Unfolding of a DFunId -- See Note [DFun unfoldings] -- df = /\a1..am. \d1..dn. MkD t1 .. tk -- (op1 a1..am d1..dn) -- (op2 a1..am d1..dn) df_bndrs :: [Var], -- The bound variables [a1..m],[d1..dn] df_con :: DataCon, -- The dictionary data constructor (never a newtype datacon) df_args :: [CoreExpr] -- Args of the data con: types, superclasses and methods, } -- in positional order That in turn allowed me to re-enable the DFunUnfolding specialisation in DsBinds. Lots of details here in TcInstDcls: Note [SPECIALISE instance pragmas] I also did some refactoring, in particular to pass the InScopeSet to exprIsConApp_maybe (which in turn means it has to go to a RuleFun). NB: Interface file format has changed!
* Make the desugarer a tiny bit cleverer on coercions (fixes Trac #7837)Simon Peyton Jones2013-04-161-2/+31
| | | | | | | The desugarer was generating a redundant box/unbox pair on the LHS of a RULE, which in turn made matching fail. See Note [Simple coercions] in DsBinds.
* typosGabor Greif2013-01-301-2/+2
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* Merge branch 'master' of darcs.haskell.org:/home/darcs/ghcSimon Peyton Jones2013-01-021-1/+2
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| * Implement overlapping type family instances.Richard Eisenberg2012-12-211-1/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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.
* | Define ListSetOps.getNth, and use itSimon Peyton Jones2013-01-021-1/+2
|/ | | | | | | | I was tracking down an error looking like Prelude.(!!): index too large which is very unhelpful. This patch replaces at least some uses of (!!) in GHC with getNth, which has a more helpful error message (with DEBUG anyway)
* Rename remaining FastBytes usages to ByteStringIan Lynagh2012-12-141-1/+1
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* Make the opt_UF_* static flags dynamicIan Lynagh2012-10-091-12/+16
| | | | | | | | I also removed the default values from the "Discounts and thresholds" note: most of them were no longer up-to-date. Along the way I added FloatSuffix to the argument parser, analogous to IntSuffix.
* Refactor the handling of kind errorsSimon Peyton Jones2012-09-281-4/+0
| | | | | | | | | | | | * Treat kind-equality constraints as *derived* equalities, with no evidence. That is really what they are at the moment. * Get rid of EvKindCast and friends. * Postpone kind errors properly to the constraint solver (lots of small knock-on effects) I moved SwapFlag to BasicTypes as well
* Implement 'left' and 'right' coercionsSimon Peyton Jones2012-09-171-0/+1
| | | | | | | | | | | | | | | | | | | | | This patch finally adds 'left' and 'right' coercions back into GHC. Trac #7205 gives the details. The main change is to add a new constructor to Coercion: data Coercion = ... | NthCo Int Coercion -- OLD, still there | LRCo LeftOrRight Coercion -- NEW data LeftOrRight = CLeft | CRight Plus: * Similar change to TcCoercion * Use LRCo when decomposing AppTys * Coercion optimisation needs to handle left/right The rest is just knock-on effects.
* Improve the binding location of class methods (I think)Simon Peyton Jones2012-09-171-2/+3
| | | | | | I've totally forgotten what this patch is fixing, but it's all about getting the right source location for class methods. It's fairly minor, but annoying that I can't connect it with a Trac ticket
* Fix Trac #7196 by adding a case to the desugarerSimon Peyton Jones2012-08-291-5/+6
| | | | Pls merge to 7.6
* Implement FastBytes, and use it for MachStrIan Lynagh2012-07-141-1/+1
| | | | | | | | | | | | | This is a first step on the way to refactoring the FastString type. FastBytes currently has no unique, mainly because there isn't currently a nice way to produce them in Binary. Also, we don't currently do the "Dictionary" thing with FastBytes in Binary. I'm not sure whether this is important. We can change both decisions later, but in the meantime this gets the refactoring underway.
* Pass DynFlags down to showSDocIan Lynagh2012-06-121-2/+2
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* Use fresh uniques when unboxing coercions in the desugarerSimon Peyton Jones2012-05-091-26/+33
| | | | | This is kosher, and turns out to be vital when we have more complicate evidence terms.
* Yet another major refactoring of the constraint solverSimon Peyton Jones2012-05-071-21/+34
| | | | | | | | | | | | | | | | | | | | | This is the result of Simon and Dimitrios doing a code walk through. There is no change in behaviour, but the structure is much better. Main changes: * Given constraints contain an EvTerm not an EvVar * Correspondingly, TcEvidence is a recursive types that uses EvTerms rather than EvVars * Rename CtFlavor to CtEvidence * Every CtEvidence has a ctev_pred field. And use record fields consistently for CtEvidence * The solved-constraint fields of InertSet (namely inert_solved and inert_solved_funeqs) contain CtEvidence, not Ct There is a long cascade of follow-on changes.
* Merge remote-tracking branch 'origin/master' into type-natsIavor S. Diatchki2012-03-131-6/+33
|\ | | | | | | | | | | | | | | | | | | | | | | | | Conflicts: compiler/coreSyn/CoreLint.lhs compiler/deSugar/DsBinds.lhs compiler/hsSyn/HsTypes.lhs compiler/iface/IfaceType.lhs compiler/rename/RnHsSyn.lhs compiler/rename/RnTypes.lhs compiler/stgSyn/StgLint.lhs compiler/typecheck/TcHsType.lhs compiler/utils/ListSetOps.lhs
| * Attach INLINE pagmas in mutually recursive bindingsSimon Peyton Jones2012-03-041-2/+29
| | | | | | | | | | | | This should fix #5895. It seems that I was silently ignoring INLINE pragmas in mutual recursion, which is not the right thing at all.
| * Refactoring around super-kindsSimon Peyton Jones2012-02-161-1/+1
| | | | | | | | | | And in particular we now have BOX :: BOX See Note [SuperKind (BOX)] in TysPrim
* | Add support for type-level "strings".Iavor S. Diatchki2012-01-241-1/+4
| | | | | | | | | | | | | | | | | | | | | | | | These are types that look like "this" and "that". They are of kind `Symbol`, defined in module `GHC.TypeLits`. For each type-level symbol `X`, we have a singleton type, `TSymbol X`. The value of the singleton type can be named with the overloaded constant `tSymbol`. Here is an example: tSymbol :: TSymbol "Hello"
* | Merge remote-tracking branch 'origin/master' into type-natsIavor S. Diatchki2012-01-241-24/+41
|\ \ | |/ | | | | | | Conflicts: compiler/typecheck/TcEvidence.lhs
| * Fix validateIan Lynagh2012-01-191-1/+4
| | | | | | | | | | | | | | | | This patch defines a flag -fno-warn-pointless-pragmas, and uses it to disable some warnings in the containers package. Along the way, also made a ContainsDynFlags class, and added a HasDynFlags instance for IOEnv (and thus TcRnIf and DsM).
| * Warn when a SPECIALISE pragma gives rise to a totally inactive ruleSimon Peyton Jones2012-01-171-24/+38
| | | | | | | | See Trac #5779
* | Merge in more HEAD, fix stuff upSimon Peyton Jones2012-01-231-2/+8
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| * Implememt -fdefer-type-errors (Trac #5624)Simon Peyton Jones2012-01-121-1/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch implements the idea of deferring (most) type errors to runtime, instead emitting only a warning at compile time. The basic idea is very simple: * The on-the-fly unifier in TcUnify never fails; instead if it gets stuck it emits a constraint. * The constraint solver tries to solve the constraints (and is entirely unchanged, hooray). * The remaining, unsolved constraints (if any) are passed to TcErrors.reportUnsolved. With -fdefer-type-errors, instead of emitting an error message, TcErrors emits a warning, AND emits a binding for the constraint witness, binding it to (error "the error message"), via the new form of evidence TcEvidence.EvDelayedError. So, when the program is run, when (and only when) that witness is needed, the program will crash with the exact same error message that would have been given at compile time. Simple really. But, needless to say, the exercise forced me into some major refactoring. * TcErrors is almost entirely rewritten * EvVarX and WantedEvVar have gone away entirely * ErrUtils is changed a bit: * New Severity field in ErrMsg * Renamed the type Message to MsgDoc (this change touches a lot of files trivially) * One minor change is that in the constraint solver we try NOT to combine insoluble constraints, like Int~Bool, else all such type errors get combined together and result in only one error message! * I moved some definitions from TcSMonad to TcRnTypes, where they seem to belong more
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