1. 02 Sep, 2017 1 commit
    • Ryan Scott's avatar
      Fix #14167 by using isGadtSyntaxTyCon in more places · 8e4229ab
      Ryan Scott authored
      Summary:
      Two places in GHC effectively attempt to //guess// whether a data type
      was declared using GADT syntax:
      
      1. When reifying a data type in Template Haskell
      2. When pretty-printing a data type (e.g., via `:info` in GHCi)
      
      But there's no need for heuristics here, since we have a 100% accurate way to
      determine whether a data type was declared using GADT syntax: the
      `isGadtSyntaxTyCon` function! By simply using that as the metric, we obtain
      far more accurate TH reification and pretty-printing results.
      
      This is technically a breaking change, since Template Haskell reification will
      now reify some data type constructors as `(Rec)GadtC` that it didn't before,
      and some data type constructors that were previously reified as `(Rec)GadtC`
      will no longer be reified as such. But it's a very understandable breaking
      change, since the previous behavior was simply incorrect.
      
      Test Plan: ./validate
      
      Reviewers: simonpj, goldfire, austin, bgamari
      
      Reviewed By: simonpj
      
      Subscribers: rwbarton, thomie
      
      GHC Trac Issues: #14167
      
      Differential Revision: https://phabricator.haskell.org/D3901
      8e4229ab
  2. 14 Jul, 2016 1 commit
  3. 15 Jun, 2016 1 commit
    • 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
  4. 26 Apr, 2016 1 commit
    • 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
  5. 11 Dec, 2015 1 commit
    • eir@cis.upenn.edu's avatar
      Add kind equalities to GHC. · 67465497
      eir@cis.upenn.edu authored
      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.
      67465497
  6. 16 Jul, 2015 1 commit
  7. 03 Jun, 2014 1 commit