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* template-haskell: Add putDoc, getDoc, withDecDoc and friendsLuke Lau2021-03-104-1/+220
| | | | | | | | | | | | | | | | | | | | | | | This adds two new methods to the Quasi class, putDoc and getDoc. They allow Haddock documentation to be added to declarations, module headers, function arguments and class/type family instances, as well as looked up. It works by building up a map of names to attach pieces of documentation to, which are then added in the extractDocs function in GHC.HsToCore.Docs. However because these template haskell names need to be resolved to GHC names at the time they are added, putDoc cannot directly add documentation to declarations that are currently being spliced. To remedy this, withDecDoc/withDecsDoc wraps the operation with addModFinalizer, and provides a more ergonomic interface for doing so. Similarly, the funD_doc, dataD_doc etc. combinators provide a more ergonomic interface for documenting functions and their arguments simultaneously. This also changes ArgDocMap to use an IntMap rather than an Map Int, for efficiency. Part of the work towards #5467
* Require GHC 8.10 as the minimum compiler for bootstrappingRyan Scott2021-03-091-9/+5
| | | | | | | Now that GHC 9.0.1 is released, it is time to drop support for bootstrapping with GHC 8.8, as we only support building with the previous two major GHC releases. As an added bonus, this allows us to remove several bits of CPP that are either always true or no longer reachable.
* Implement BoxedRep proposalwip/boxed-repBen Gamari2021-03-071-0/+8
| | | | | | | | | | | | | | | | | | | | | | | This implements the BoxedRep proposal, refactoring the `RuntimeRep` hierarchy from: ```haskell data RuntimeRep = LiftedPtrRep | UnliftedPtrRep | ... ``` to ```haskell data RuntimeRep = BoxedRep Levity | ... data Levity = Lifted | Unlifted ``` Updates binary, haddock submodules. Closes #17526. Metric Increase: T12545
* Fix #19363 by using pprName' {Applied,Infix} in the right placesRyan Scott2021-02-261-22/+22
| | | | | | | | | | | | It was revealed in #19363 that the Template Haskell pretty-printer implemented in `Language.Haskell.TH.Ppr` did not pretty-print infix names or symbolic names correctly in certain situations, such as in data constructor declarations or fixity declarations. Easily fixed by using `pprName' Applied` (which always parenthesizes symbolic names in prefix position) or `pprName' Infix` (which always surrounds alphanumeric names with backticks in infix position) in the right spots. Fixes #19363.
* Fix TemplateHaskell pretty printer for CompleteP (#19270)Ole Krüger2021-02-221-1/+1
| | | | The COMPLETE pragma was not properly terminated with a '#-}'.
* The Char kind (#11342)Daniel Rogozin2021-02-064-1/+6
| | | | | | | | | | | | | | | | | | | | | | Co-authored-by: Rinat Stryungis <rinat.stryungis@serokell.io> Implement GHC Proposal #387 * Parse char literals 'x' at the type level * New built-in type families CmpChar, ConsSymbol, UnconsSymbol * New KnownChar class (cf. KnownSymbol and KnownNat) * New SomeChar type (cf. SomeSymbol and SomeNat) * CharTyLit support in template-haskell Updated submodules: binary, haddock. Metric Decrease: T5205 haddock.base Metric Increase: Naperian T13035
* Revert "Implement BoxedRep proposal"Ben Gamari2020-12-151-8/+0
| | | | | | This was inadvertently merged. This reverts commit 6c2eb2232b39ff4720fda0a4a009fb6afbc9dcea.
* Implement BoxedRep proposalAndrew Martin2020-12-141-0/+8
| | | | | | | | | | | | | | | | | | This implements the BoxedRep proposal, refacoring the `RuntimeRep` hierarchy from: ```haskell data RuntimeRep = LiftedPtrRep | UnliftedPtrRep | ... ``` to ```haskell data RuntimeRep = BoxedRep Levity | ... data Levity = Lifted | Unlifted ``` Closes #17526.
* Implement type applications in patternsCale Gibbard2020-12-144-8/+19
| | | | | The haddock submodule is also updated so that it understands the changes to patterns.
* New linear types syntax: a %p -> b (#18459)Vladislav Zavialov2020-09-291-2/+2
| | | | | | Implements GHC Proposal #356 Updates the haddock submodule.
* Make CodeQ and TExpQ levity polymorphicRyan Scott2020-08-052-3/+18
| | | | | | | | | | | | The patch is quite straightforward. The only tricky part is that `Language.Haskell.TH.Lib.Internal` now must be `Trustworthy` instead of `Safe` due to the `GHC.Exts` import (in order to import `TYPE`). Since `CodeQ` has yet to appear in any released version of `template-haskell`, I didn't bother mentioning the change to `CodeQ` in the `template-haskell` release notes. Fixes #18521.
* Use a newtype `Code` for the return type of typed quotations (Proposal #195)Matthew Pickering2020-07-215-52/+132
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | There are three problems with the current API: 1. It is hard to properly write instances for ``Quote m => m (TExp a)`` as the type is the composition of two type constructors. Doing so in your program involves making your own newtype and doing a lot of wrapping/unwrapping. For example, if I want to create a language which I can either run immediately or generate code from I could write the following with the new API. :: class Lang r where _int :: Int -> r Int _if :: r Bool -> r a -> r a -> r a instance Lang Identity where _int = Identity _if (Identity b) (Identity t) (Identity f) = Identity (if b then t else f) instance Quote m => Lang (Code m) where _int = liftTyped _if cb ct cf = [|| if $$cb then $$ct else $$cf ||] 2. When doing code generation it is common to want to store code fragments in a map. When doing typed code generation, these code fragments contain a type index so it is desirable to store them in one of the parameterised map data types such as ``DMap`` from ``dependent-map`` or ``MapF`` from ``parameterized-utils``. :: compiler :: Env -> AST a -> Code Q a data AST a where ... data Ident a = ... type Env = MapF Ident (Code Q) newtype Code m a = Code (m (TExp a)) In this example, the ``MapF`` maps an ``Ident String`` directly to a ``Code Q String``. Using one of these map types currently requires creating your own newtype and constantly wrapping every quotation and unwrapping it when using a splice. Achievable, but it creates even more syntactic noise than normal metaprogramming. 3. ``m (TExp a)`` is ugly to read and write, understanding ``Code m a`` is easier. This is a weak reason but one everyone can surely agree with. Updates text submodule.
* Implement the proposed -XQualifiedDo extensionMatthias Pall Gissurarson2020-06-264-8/+28
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Co-authored-by: Facundo Domínguez <facundo.dominguez@tweag.io> QualifiedDo is implemented using the same placeholders for operation names in the AST that were devised for RebindableSyntax. Whenever the renamer checks which names to use for do syntax, it first checks if the do block is qualified (e.g. M.do { stmts }), in which case it searches for qualified names in the module M. This allows users to write {-# LANGUAGE QualifiedDo #-} import qualified SomeModule as M f x = M.do -- desugars to: y <- M.return x -- M.return x M.>>= \y -> M.return y -- M.return y M.>> M.return y -- M.return y See Note [QualifiedDo] and the users' guide for more details. Issue #18214 Proposal: https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0216-qualified-do.rst Since we change the constructors `ITdo` and `ITmdo` to carry the new module name, we need to bump the haddock submodule to account or the new shape of these constructors.
* Linear types (#15981)Krzysztof Gogolewski2020-06-174-0/+15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This is the first step towards implementation of the linear types proposal (https://github.com/ghc-proposals/ghc-proposals/pull/111). It features * A language extension -XLinearTypes * Syntax for linear functions in the surface language * Linearity checking in Core Lint, enabled with -dlinear-core-lint * Core-to-core passes are mostly compatible with linearity * Fields in a data type can be linear or unrestricted; linear fields have multiplicity-polymorphic constructors. If -XLinearTypes is disabled, the GADT syntax defaults to linear fields The following items are not yet supported: * a # m -> b syntax (only prefix FUN is supported for now) * Full multiplicity inference (multiplicities are really only checked) * Decent linearity error messages * Linear let, where, and case expressions in the surface language (each of these currently introduce the unrestricted variant) * Multiplicity-parametric fields * Syntax for annotating lambda-bound or let-bound with a multiplicity * Syntax for non-linear/multiple-field-multiplicity records * Linear projections for records with a single linear field * Linear pattern synonyms * Multiplicity coercions (test LinearPolyType) A high-level description can be found at https://ghc.haskell.org/trac/ghc/wiki/LinearTypes/Implementation Following the link above you will find a description of the changes made to Core. This commit has been authored by * Richard Eisenberg * Krzysztof Gogolewski * Matthew Pickering * Arnaud Spiwack With contributions from: * Mark Barbone * Alexander Vershilov Updates haddock submodule.
* Fix #12073: Add MonadFix Q instanceOleg Grenrus2020-06-131-0/+22
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* Rename the singleton tuple GHC.Tuple.Unit to GHC.Tuple.SoloTom Ellis2020-06-011-1/+1
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* Clean up file paths for new module hierarchyTakenobu Tani2020-06-011-1/+1
| | | | | | | | | This updates comments only. This patch replaces file references according to new module hierarchy. See also: * https://gitlab.haskell.org/ghc/ghc/-/wikis/Make-GHC-codebase-more-modular * https://gitlab.haskell.org/ghc/ghc/issues/13009
* Add Semigroup/Monoid for Q (#18123)Vladislav Zavialov2020-05-281-0/+9
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* Explicit SpecificityGert-Jan Bottu2020-05-215-60/+94
| | | | | | | | | | | | | | | | | | | | Implementation for Ticket #16393. Explicit specificity allows users to manually create inferred type variables, by marking them with braces. This way, the user determines which variables can be instantiated through visible type application. The additional syntax is included in the parser, allowing users to write braces in type variable binders (type signatures, data constructors etc). This information is passed along through the renamer and verified in the type checker. The AST for type variable binders, data constructors, pattern synonyms, partial signatures and Template Haskell has been updated to include the specificity of type variables. Minor notes: - Bumps haddock submodule - Disables pattern match checking in GHC.Iface.Type with GHC 8.8
* Define a Quote IO instanceRyan Scott2020-04-281-2/+8
| | | | Fixes #18103.
* TH: fix Show/Eq/Ord instances for Bytes (#16457)Sylvain Henry2020-04-271-1/+42
| | | | We shouldn't compare pointer values but the actual bytes.
* Modules (#13009)Sylvain Henry2020-04-181-2/+2
| | | | | | | | | | | | | | * SysTools * Parser * GHC.Builtin * GHC.Iface.Recomp * Settings Update Haddock submodule Metric Decrease: Naperian parsing001
* Modules: type-checker (#13009)Sylvain Henry2020-04-071-1/+1
| | | | Update Haddock submodule
* Require GHC 8.8 as the minimum compiler for bootstrappingRyan Scott2020-03-311-8/+3
| | | | | | | | This allows us to remove several bits of CPP that are either always true or no longer reachable. As an added bonus, we no longer need to worry about importing `Control.Monad.Fail.fail` qualified to avoid clashing with `Control.Monad.fail`, since the latter is now the same as the former.
* Generalize liftData to work over any Quote (#17857)Ryan Scott2020-02-201-19/+19
| | | | | | | | | The Overloaded Quotations proposal generalized the type of `lift` to work over any `Quote`, but not the type of `liftData`, leading to #17857. Thankfully, generalizing `liftData` is extremely straightforward. Fixes #17857.
* Module hierarchy: HsToCore (cf #13009)Sylvain Henry2020-02-141-2/+3
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* Add explicit LANGUAGE Safe to template-haskellOleg Grenrus2020-02-148-2/+10
| | | (cherry picked from commit a5e0f376821ca882880b03b07b451aa574e289ec)
* Overloaded Quotation Brackets (#246)Matthew Pickering2020-01-124-457/+481
| | | | | | | | | | | | | | | | | | This patch implements overloaded quotation brackets which generalise the desugaring of all quotation forms in terms of a new minimal interface. The main change is that a quotation, for example, [e| 5 |], will now have type `Quote m => m Exp` rather than `Q Exp`. The `Quote` typeclass contains a single method for generating new names which is used when desugaring binding structures. The return type of functions from the `Lift` type class, `lift` and `liftTyped` have been restricted to `forall m . Quote m => m Exp` rather than returning a result in a Q monad. More details about the feature can be read in the GHC proposal. https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0246-overloaded-bracket.rst
* Fix typos, via a Levenshtein-style correctorBrian Wignall2020-01-041-1/+1
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* Parenthesize the * kind in TH.PprVladislav Zavialov2019-12-051-12/+19
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* Fix typos, using Wikipedia list of common typosBrian Wignall2019-11-281-1/+1
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* Clean up TH's treatment of unary tuples (or, #16881 part two)Ryan Scott2019-11-071-4/+20
| | | | | | | | | | | | | | !1906 left some loose ends in regards to Template Haskell's treatment of unary tuples. This patch ends to tie up those loose ends: * In addition to having `TupleT 1` produce unary tuples, `TupE [exp]` and `TupP [pat]` also now produce unary tuples. * I have added various special cases in GHC's pretty-printers to ensure that explicit 1-tuples are printed using the `Unit` type. See `testsuite/tests/th/T17380`. * The GHC 8.10.1 release notes entry has been tidied up a little. Fixes #16881. Fixes #17371. Fixes #17380.
* Template Haskell: make unary tuples legal (#16881)nineonine2019-10-131-20/+11
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* Standalone kind signatures (#16794)wip/top-level-kind-signaturesVladislav Zavialov2019-09-254-1/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Implements GHC Proposal #54: .../ghc-proposals/blob/master/proposals/0054-kind-signatures.rst With this patch, a type constructor can now be given an explicit standalone kind signature: {-# LANGUAGE StandaloneKindSignatures #-} type Functor :: (Type -> Type) -> Constraint class Functor f where fmap :: (a -> b) -> f a -> f b This is a replacement for CUSKs (complete user-specified kind signatures), which are now scheduled for deprecation. User-facing changes ------------------- * A new extension flag has been added, -XStandaloneKindSignatures, which implies -XNoCUSKs. * There is a new syntactic construct, a standalone kind signature: type <name> :: <kind> Declarations of data types, classes, data families, type families, and type synonyms may be accompanied by a standalone kind signature. * A standalone kind signature enables polymorphic recursion in types, just like a function type signature enables polymorphic recursion in terms. This obviates the need for CUSKs. * TemplateHaskell AST has been extended with 'KiSigD' to represent standalone kind signatures. * GHCi :info command now prints the kind signature of type constructors: ghci> :info Functor type Functor :: (Type -> Type) -> Constraint ... Limitations ----------- * 'forall'-bound type variables of a standalone kind signature do not scope over the declaration body, even if the -XScopedTypeVariables is enabled. See #16635 and #16734. * Wildcards are not allowed in standalone kind signatures, as partial signatures do not allow for polymorphic recursion. * Associated types may not be given an explicit standalone kind signature. Instead, they are assumed to have a CUSK if the parent class has a standalone kind signature and regardless of the -XCUSKs flag. * Standalone kind signatures do not support multiple names at the moment: type T1, T2 :: Type -> Type -- rejected type T1 = Maybe type T2 = Either String See #16754. * Creative use of equality constraints in standalone kind signatures may lead to GHC panics: type C :: forall (a :: Type) -> a ~ Int => Constraint class C a where f :: C a => a -> Int See #16758. Implementation notes -------------------- * The heart of this patch is the 'kcDeclHeader' function, which is used to kind-check a declaration header against its standalone kind signature. It does so in two rounds: 1. check user-written binders 2. instantiate invisible binders a la 'checkExpectedKind' * 'kcTyClGroup' now partitions declarations into declarations with a standalone kind signature or a CUSK (kinded_decls) and declarations without either (kindless_decls): * 'kinded_decls' are kind-checked with 'checkInitialKinds' * 'kindless_decls' are kind-checked with 'getInitialKinds' * DerivInfo has been extended with a new field: di_scoped_tvs :: ![(Name,TyVar)] These variables must be added to the context in case the deriving clause references tcTyConScopedTyVars. See #16731.
* TemplateHaskell: reifyType (#16976)Vladislav Zavialov2019-07-262-0/+13
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* Fix #16895 by checking whether infix expression operator is a variablenineonine2019-07-052-6/+13
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* Fix #15843 by extending Template Haskell AST for tuples to support sectionsnineonine2019-07-024-21/+61
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* fix Template Haskell cross compilation on 64 bit compiler with 32 bit targetLuite Stegeman2019-05-222-7/+8
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* TH: make `Lift` and `TExp` levity-polymorphicAlec Theriault2019-04-181-16/+214
| | | | | | | | | | | | | | | | | | | | | | | | | | | | Besides the obvious benefits of being able to manipulate `TExp`'s of unboxed types, this also simplified `-XDeriveLift` all while making it more capable. * `ghc-prim` is explicitly depended upon by `template-haskell` * The following TH things are parametrized over `RuntimeRep`: - `TExp(..)` - `unTypeQ` - `unsafeTExpCoerce` - `Lift(..)` * The following instances have been added to `Lift`: - `Int#`, `Word#`, `Float#`, `Double#`, `Char#`, `Addr#` - unboxed tuples of lifted types up to arity 7 - unboxed sums of lifted types up to arity 7 Ideally we would have levity-polymorphic _instances_ of unboxed tuples and sums. * The code generated by `-XDeriveLift` uses expression quotes instead of generating large amounts of TH code and having special hard-coded cases for some unboxed types.
* Update Wiki URLs to point to GitLabTakenobu Tani2019-03-251-3/+3
| | | | | | | | | | | | | | | | | | | | | | | This moves all URL references to Trac Wiki to their corresponding GitLab counterparts. This substitution is classified as follows: 1. Automated substitution using sed with Ben's mapping rule [1] Old: ghc.haskell.org/trac/ghc/wiki/XxxYyy... New: gitlab.haskell.org/ghc/ghc/wikis/xxx-yyy... 2. Manual substitution for URLs containing `#` index Old: ghc.haskell.org/trac/ghc/wiki/XxxYyy...#Zzz New: gitlab.haskell.org/ghc/ghc/wikis/xxx-yyy...#zzz 3. Manual substitution for strings starting with `Commentary` Old: Commentary/XxxYyy... New: commentary/xxx-yyy... See also !539 [1]: https://gitlab.haskell.org/bgamari/gitlab-migration/blob/master/wiki-mapping.json
* Update Trac ticket URLs to point to GitLabRyan Scott2019-03-152-6/+6
| | | | | This moves all URL references to Trac tickets to their corresponding GitLab counterparts.
* TH: support raw bytes literals (#14741)Sylvain Henry2019-03-084-1/+40
| | | | | | | | | | | | | | | | | | | GHC represents String literals as ByteString internally for efficiency reasons. However, until now it wasn't possible to efficiently create large string literals with TH (e.g. to embed a file in a binary, cf #14741): TH code had to unpack the bytes into a [Word8] that GHC then had to re-pack into a ByteString. This patch adds the possibility to efficiently create a "string" literal from raw bytes. We get the following compile times for different sizes of TH created literals: || Size || Before || After || Gain || || 30K || 2.307s || 2.299 || 0% || || 3M || 3.073s || 2.400s || 21% || || 30M || 8.517s || 3.390s || 60% || Ticket #14741 can be fixed if the original code uses this new TH feature.
* Visible dependent quantificationRyan Scott2019-03-014-6/+28
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This implements GHC proposal 35 (https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0035-forall-arrow.rst) by adding the ability to write kinds with visible dependent quantification (VDQ). Most of the work for supporting VDQ was actually done _before_ this patch. That is, GHC has been able to reason about kinds with VDQ for some time, but it lacked the ability to let programmers directly write these kinds in the source syntax. This patch is primarly about exposing this ability, by: * Changing `HsForAllTy` to add an additional field of type `ForallVisFlag` to distinguish between invisible `forall`s (i.e, with dots) and visible `forall`s (i.e., with arrows) * Changing `Parser.y` accordingly The rest of the patch mostly concerns adding validity checking to ensure that VDQ is never used in the type of a term (as permitting this would require full-spectrum dependent types). This is accomplished by: * Adding a `vdqAllowed` predicate to `TcValidity`. * Introducing `splitLHsSigmaTyInvis`, a variant of `splitLHsSigmaTy` that only splits invisible `forall`s. This function is used in certain places (e.g., in instance declarations) to ensure that GHC doesn't try to split visible `forall`s (e.g., if it tried splitting `instance forall a -> Show (Blah a)`, then GHC would mistakenly allow that declaration!) This also updates Template Haskell by introducing a new `ForallVisT` constructor to `Type`. Fixes #16326. Also fixes #15658 by documenting this feature in the users' guide.
* Add `liftedTyped` to `Lift` classAlec Theriault2019-02-131-4/+54
| | | | | | | | Implements GHC proposal 43, adding a `liftTyped` method to the `Lift` typeclass. This also adds some documentation to `TExp`, describing typed splices and their advantages over their untyped counterparts. Resolves #14671.
* Add support for ASM foreign files (.s) in TH (#16180)Sylvain Henry2019-01-201-4/+5
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* Prepare source-tree for base-4.13 MFP bumpHerbert Valerio Riedel2019-01-181-1/+3
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* Visible kind applicationmynguyen2019-01-034-74/+112
| | | | | | | | | | | | | | | | | | | | | | | Summary: This patch implements visible kind application (GHC Proposal 15/#12045), as well as #15360 and #15362. It also refactors unnamed wildcard handling, and requires that type equations in type families in Template Haskell be written with full type on lhs. PartialTypeSignatures are on and warnings are off automatically with visible kind application, just like in term-level. There are a few remaining issues with this patch, as documented in ticket #16082. Includes a submodule update for Haddock. Test Plan: Tests T12045a/b/c/TH1/TH2, T15362, T15592a Reviewers: simonpj, goldfire, bgamari, alanz, RyanGlScott, Iceland_jack Subscribers: ningning, Iceland_jack, RyanGlScott, int-index, rwbarton, mpickering, carter GHC Trac Issues: `#12045`, `#15362`, `#15592`, `#15788`, `#15793`, `#15795`, `#15797`, `#15799`, `#15801`, `#15807`, `#15816` Differential Revision: https://phabricator.haskell.org/D5229
* Fix embarrassing infinite loop in pprParendTypeRyan Scott2018-12-031-1/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | Summary: `pprParendType` was missing an explicit case for `EqualityT`, which caused it to fall through to a catch-all case that invokes `ppr`. But `ppr` itself does not have a case for a partial application of `EqualityT`, so //it// falls back to `pprParendType`, resulting in an infinite loop! The fix is simple: add a case for `EqualityT` in `pprParendType`. While I was in the neighborhood, I removed the catch-call case in `pprParendType` to make this sort of mistake less likely to happen in the future. Test Plan: make test TEST=T15985 Reviewers: bgamari, monoidal, simonpj Reviewed By: monoidal, simonpj Subscribers: rwbarton, carter GHC Trac Issues: #15985 Differential Revision: https://phabricator.haskell.org/D5403
* Add 'Lift' instances for 'NonEmpty' and 'Void'Alec Theriault2018-11-301-0/+16
| | | | | | | | | | | | | | | | | | | | Summary: Since 'NonEmpty' and 'Void' are now part of 'base', it makes sense that we put 'Lift' instances for them in 'template-haskell'. Not doing so is going to force users to define their own (possibly colliding) orphan instances downstream. Test Plan: ./validate Reviewers: goldfire, bgamari, RyanGlScott Reviewed By: RyanGlScott Subscribers: RyanGlScott, rwbarton, carter GHC Trac Issues: #15961 Differential Revision: https://phabricator.haskell.org/D5391
* More explicit foralls (GHC Proposal 0007)Matthew Yacavone2018-10-274-46/+85
| | | | | | | | | | | | | | | | | | | | | | | | | | | Allow the user to explicitly bind type/kind variables in type and data family instances (including associated instances), closed type family equations, and RULES pragmas. Follows the specification of GHC Proposal 0007, also fixes #2600. Advised by Richard Eisenberg. This modifies the Template Haskell AST -- old code may break! Other Changes: - convert HsRule to a record - make rnHsSigWcType more general - add repMaybe to DsMeta Includes submodule update for Haddock. Test Plan: validate Reviewers: goldfire, bgamari, alanz Subscribers: simonpj, RyanGlScott, goldfire, rwbarton, thomie, mpickering, carter GHC Trac Issues: #2600, #14268 Differential Revision: https://phabricator.haskell.org/D4894