diff --git a/CHANGELOG.md b/CHANGELOG.md new file mode 100644 --- /dev/null +++ b/CHANGELOG.md @@ -0,0 +1,5 @@ +# Revision history for HTree + +## 0.1.0.0 -- 2024-07-21 + +* initial release diff --git a/LICENSE b/LICENSE new file mode 100644 --- /dev/null +++ b/LICENSE @@ -0,0 +1,661 @@ + GNU AFFERO GENERAL PUBLIC LICENSE + Version 3, 19 November 2007 + + Copyright (C) 2007 Free Software Foundation, Inc. + Everyone is permitted to copy and distribute verbatim copies + of this license document, but changing it is not allowed. + + Preamble + + The GNU Affero General Public License is a free, copyleft license for +software and other kinds of works, specifically designed to ensure +cooperation with the community in the case of network server software. + + The licenses for most software and other practical works are designed +to take away your freedom to share and change the works. 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There are many ways you could offer source, and different +solutions will be better for different programs; see section 13 for the +specific requirements. + + You should also get your employer (if you work as a programmer) or school, +if any, to sign a "copyright disclaimer" for the program, if necessary. +For more information on this, and how to apply and follow the GNU AGPL, see +. diff --git a/README.md b/README.md new file mode 100644 --- /dev/null +++ b/README.md @@ -0,0 +1,69 @@ + +[![built with nix](https://img.shields.io/badge/built%20with-nix-%235277C3?logo=nixos)](https://nixos.org/) +[![built on haskell](https://img.shields.io/badge/built%20on-haskell-%235D4F85?logo=haskell)](https://www.haskell.org/) +![ci](https://ci.mangoiv.com/api/badges/5/status.svg) +[![haddock](https://img.shields.io/badge/haddock-mangoiv.com-e0b0ff)](https://mangoiv.com/htree) + +# `htree`: heterogeneous rose tree + +This library implements a heterogeneous rose-tree (`HTree`) that is indexed by a +type-level rosetree (`TyTree`). + +It also offers some useful functions, highlights include: +- searching in the tree and creating evidence on the term-level via typeclasses +- record-dot syntax for accessing elements in the tree. +- mapping and traversing trees + +## to develop + +- with `direnv`: `direnv allow` +- only with nix: `nix develop` +- to run all checks: `nix flake check -Lv` + systems configurations +- build with nix `nix build` (or on `ghc96`, `nix build .#ghc96-htree`) +- documentation in the form of continuously deployed haddock can be found at [mangoiv.srht.site](https://mangoiv.srht.site/htree/index.html) + +## example + +```haskell +pattern I :: forall a. a -> Identity a +pattern I a = Identity a + +-- the type that the tree is going to be indexed by +type Ex = + TyNode Int + [ TyNode Int + [ TyNode Int '[] + , TyNode Bool '[] + , TyNode String '[ TyNode Int '[]] + ] + , TyNode Int '[] + ] + +-- we create an HTree of the example type 'Ex' +ex :: HTree Identity Ex +ex = + HNode 5 do + HNode 12 do + HNode 13 HNil + ::: HNode (I False) HNil + ::: HNode "test" (HNode 9 HNil ::: HNil) + ::: HNil + ::: HNode 43 HNil + ::: HNil + + +-- we can create a labeled Tree and search via DFS and BFS in it +-- the search happens on the type-level +type LabeledTree = TyNodeL "top" Int + [ TyNodeL "inter" Int '[ TyNodeL "foo" Int '[] ] + , TyNodeL "foo" Int '[] + ] + +-- >>> getElem @'DFS @"foo" @Int Proxy labeledTree +-- Identity 69 +-- >>> getElem @'BFS @"foo" @Int Proxy labeledTree +-- Identity 67 +labeledTree :: HTree Identity LabeledTree +labeledTree = 42 `HNodeL` HNodeL 4 (HNodeL 69 HNil ::: HNil) ::: HNodeL 67 HNil ::: HNil +``` diff --git a/htree.cabal b/htree.cabal new file mode 100644 --- /dev/null +++ b/htree.cabal @@ -0,0 +1,85 @@ +cabal-version: 3.4 +name: htree +tested-with: GHC ==9.2.8 || ==9.4.8 || ==9.6.4 || ==9.8.1 +version: 0.1.1.0 +synopsis: + a library to build and work with heterogeneous, type level indexed rose trees + +description: + This library implements a heterogeneous rose-tree (HTree) that is indexed by a type-level rosetree (TyTree). + + It also offers some useful functions, highlights include: + + searching in the tree and creating evidence on the term-level via typeclasses + record-dot syntax for accessing elements in the tree. + mapping and traversing trees + +license: AGPL-3.0-or-later +license-file: LICENSE +author: mangoiv +maintainer: contact@mangoiv.com +category: Data +build-type: Simple +extra-doc-files: + CHANGELOG.md + README.md + +common warnings-and-imports + ghc-options: + -Wall -fprint-explicit-kinds -fprint-explicit-foralls + -Wno-unticked-promoted-constructors -Wunused-packages + + default-extensions: + BlockArguments + DataKinds + DerivingStrategies + FunctionalDependencies + GADTs + LambdaCase + NoStarIsType + OverloadedLists + OverloadedStrings + PatternSynonyms + QuantifiedConstraints + TypeFamilies + ViewPatterns + + build-depends: base >=4.16 && <5 + +library + import: warnings-and-imports + exposed-modules: + Data.HTree + Data.HTree.Constraint + Data.HTree.Existential + Data.HTree.Families + Data.HTree.Labeled + Data.HTree.List + Data.HTree.Tree + + hs-source-dirs: src + default-language: GHC2021 + +test-suite htree-test + import: warnings-and-imports + default-language: GHC2021 + other-modules: + Spec.HTree.Fixtures + Spec.HTree.Fold + Spec.HTree.Helpers + Spec.HTree.Labeled + Spec.HTree.Orphans + Spec.HTree.TH + Spec.HTree.Traverse + + type: exitcode-stdio-1.0 + hs-source-dirs: test + main-is: Main.hs + build-depends: + , containers + , hspec + , htree + , QuickCheck + , quickcheck-instances + , template-haskell + , th-compat diff --git a/src/Data/HTree.hs b/src/Data/HTree.hs new file mode 100644 --- /dev/null +++ b/src/Data/HTree.hs @@ -0,0 +1,51 @@ +-- | a module for useful reexports from the modules +module Data.HTree + ( -- * lists + HL.HList (..) + + -- * trees + , HT.HTree (..) + , pattern L.HNodeL + , HT.TyTree (..) + , type L.TyNodeL + + -- ** mapping a tree + , HT.hmap + , HT.hcmap + + -- ** traversing a tree + , HT.htraverse + , HT.hctraverse + + -- ** folding a tree + + -- *** value level + , HT.hFoldMap + , HT.hcFoldMap + , HT.hFlatten + + -- *** type level + , HT.FlattenTree + , HT.FlattenForest + + -- ** searching a tree + , L.Labeled (..) + , L.HasField (..) + , L.getElem + + -- * useful reexports + , Re.Proxy (..) + , Re.Type + , Re.Constraint + , Re.Dict + , pattern Re.Dict + , Re.withDict + ) +where + +import Data.HTree.Constraint qualified as Re +import Data.HTree.Labeled qualified as L +import Data.HTree.List qualified as HL +import Data.HTree.Tree qualified as HT +import Data.Kind qualified as Re +import Data.Proxy qualified as Re diff --git a/src/Data/HTree/Constraint.hs b/src/Data/HTree/Constraint.hs new file mode 100644 --- /dev/null +++ b/src/Data/HTree/Constraint.hs @@ -0,0 +1,71 @@ +{-# LANGUAGE UndecidableSuperClasses #-} + +-- | A couple of types to work with Constraints +module Data.HTree.Constraint + ( -- * proving a constraint + Has (..) + + -- ** synonyms for proving a constraint + , HasTypeable + , HasIs + + -- ** helpers to work with constraints + , proves + , Charge + + -- * Dict + , type Dict + , pattern Dict + + -- ** functions for working with 'Dict's + , withDict + ) +where + +import Data.Kind (Constraint, Type) +import Data.Proxy (Proxy (Proxy)) +import Type.Reflection (Typeable) + +-- | a functor useful for proving a constraint for some type +-- +-- >>> import Data.Functor.Identity +-- >>> Proves @Eq (Identity (5 :: Int)) +-- Proves (Identity 5) +type Has :: forall k. (k -> Constraint) -> (k -> Type) -> k -> Type +data Has c f k where + Proves :: c k => f k -> Has c f k + +-- | transform a 'Constraint' in something of kind @k -> 'Constraint'@ to be +-- able to use it in 'Has' +type Charge :: Constraint -> k -> Constraint +class c => Charge c a + +instance c => Charge c a + +-- | a Dict witnesses some constraint +type Dict :: Constraint -> Type +type Dict c = Has (Charge c) Proxy () + +-- | match on a 'Dict' +pattern Dict :: forall (c :: Constraint). forall. c => Dict c +pattern Dict = Proves Proxy + +{-# COMPLETE Dict #-} + +-- | destructing a 'Dict' +withDict :: Dict c -> (c => r) -> r +withDict d k = proves d (const k) + +-- | destruct a 'Has' +proves :: Has c f a -> (c a => f a -> r) -> r +proves (Proves x) k = k x + +-- | 'Has' but specialised to 'Typeable' +type HasTypeable :: (k -> Type) -> k -> Type +type HasTypeable = Has Typeable + +-- | 'Has' but specialised to a constant type, @Some (HasIs k f)@ is isomorphic to @f k@ +type HasIs :: k -> (k -> Type) -> k -> Type +type HasIs k = Has ((~) k) + +deriving stock instance Show (f k) => Show (Has c f k) diff --git a/src/Data/HTree/Existential.hs b/src/Data/HTree/Existential.hs new file mode 100644 --- /dev/null +++ b/src/Data/HTree/Existential.hs @@ -0,0 +1,194 @@ +{-# LANGUAGE UndecidableInstances #-} + +-- | Existential types and helpers to work with existentials 'HList's and 'HTree's +module Data.HTree.Existential + ( -- * existential data types + Some (..) + , Some2 (..) + + -- * existential type synonyms + , ETree + , EList + + -- * working with existential HTrees/HLists functions + , with + , with2 + , withSomeHTree + , withSomeHList + , hcFoldEHList + , hcFoldMapEHTree + + -- * useful functors to work with existential type-level structures + , Has (..) + , HasTypeable + , HasIs + + -- ** working with 'Has' + , withProves + , prodHas + , flipHas + ) +where + +import Data.HTree.Constraint (Has (Proves), HasIs, HasTypeable, proves) +import Data.HTree.Families (Both) +import Data.HTree.List (HList (HCons, HNil)) +import Data.HTree.Tree (HTree (HNode)) +import Data.Kind (Type) +import Type.Reflection (SomeTypeRep (SomeTypeRep), Typeable, eqTypeRep, typeOf, (:~~:) (HRefl)) + +-- | a Some type that takes an arity one type constructor, this is for completeness +type Some :: forall l. (l -> Type) -> Type +data Some g where + MkSome :: g k -> Some g + +-- | take some existentai arity one type constructor and a function that takes the +-- non-existential one and returns some @r@ and return an @r@ +with :: forall {l} (g :: l -> Type) r. Some g -> (forall m. g m -> r) -> r +with (MkSome a) f = f a + +-- | a Some type that take an arity two type constructor, this is necessary +-- so that we avoid using composition on the type level or having visible +-- parameters to the type synonyms +type Some2 :: forall k l. (k -> l -> Type) -> k -> Type +data Some2 g f where + MkSome2 :: g f k -> Some2 g f + +-- | take some existential arity two type constructor and a function that takes the +-- non-existential one and returns some @r@ and return an @r@ +with2 + :: forall {k} {l} (g :: k -> l -> Type) (f :: k) r + . Some2 g f + -> (forall m. g f m -> r) + -> r +with2 (MkSome2 a) f = f a + +-- | HTree but the type level tree is existential +type ETree :: forall k. (k -> Type) -> Type +type ETree = Some2 HTree + +-- | HList but the type level list is existential +type EList :: forall k. (k -> Type) -> Type +type EList = Some2 HList + +-- | 'with2' specialized to 'HTree's +withSomeHTree :: ETree f -> (forall t. HTree f t -> r) -> r +withSomeHTree = with2 + +-- | 'with2' specialized to 'HList's +withSomeHList :: EList f -> (forall xs. HList f xs -> r) -> r +withSomeHList = with2 + +-- | fold over existential hlists +hcFoldEHList + :: forall c f y + . (forall x. c x => f x -> y -> y) + -> y + -> EList (Has c f) + -> y +hcFoldEHList f def el = with2 el \case + HNil -> def + HCons (Proves x) xs -> + let y = hcFoldEHList f def (MkSome2 xs) + in f x y + +-- | fold over existential htrees +hcFoldMapEHTree + :: forall c f y + . Semigroup y + => (forall a. c a => f a -> y) + -> ETree (Has c f) + -> y +hcFoldMapEHTree f et = with2 et \case + HNode (Proves x) HNil -> f x + HNode x@(Proves _) (y `HCons` ys) -> + hcFoldMapEHTree f (MkSome2 y) + <> hcFoldMapEHTree f (MkSome2 (HNode x ys)) + +-- | destruct 'Some', destruct 'Has' +withProves :: Some (Has c f) -> (forall a. c a => f a -> r) -> r +withProves x k = with x (`proves` k) + +-- | condens the 'Has' constraints in an existential +prodHas :: forall c1 c2 f. Some (Has c1 (Has c2 f)) -> Some (Has (Both c1 c2) f) +prodHas x = withProves x \pc2 -> proves pc2 (MkSome . Proves) + +-- | flip the constraints in an existential +flipHas :: forall c1 c2 f. Some (Has c1 (Has c2 f)) -> Some (Has c2 (Has c1 f)) +flipHas x = withProves (prodHas x) (MkSome . Proves . Proves) + +deriving stock instance (forall k. Show (g f k)) => Show (Some2 g f) + +deriving stock instance (forall k. Show (g k)) => Show (Some g) + +instance {-# OVERLAPPING #-} Typeable f => Show (Some (Has Typeable f)) where + show (MkSome (Proves f)) = + "(MkSome (Proves @Typeable " <> show (typeOf f) <> "))" + +instance + (forall x. Eq x => Eq (f x), Typeable f) + => Eq (ETree (Has (Both Typeable Eq) f)) + where + ex == ey = + with2 ex \x -> with2 ey \y -> + case (x, y) of + (HNode (Proves m) ms, HNode (Proves n) ns) -> + case eqTypeRep (typeOf m) (typeOf n) of + Nothing -> False + Just HRefl -> + let go + :: forall xs ys + . HList (HTree (Has (Both Typeable Eq) f)) xs + -> HList (HTree (Has (Both Typeable Eq) f)) ys + -> Bool + go HNil HNil = True + go (m' `HCons` ms') (n' `HCons` ns') = + MkSome2 m' == MkSome2 n' && go ms' ns' + go _ _ = False + in m == n && go ms ns + +instance + (forall x. Eq x => Eq (f x), Typeable f) + => Eq (EList (Has (Both Typeable Eq) f)) + where + ex == ey = + with2 ex \x -> with2 ey \y -> + case (x, y) of + (HNil, HNil) -> True + (HCons (Proves x') xs', HCons (Proves y') ys') -> + case eqTypeRep (typeOf x') (typeOf y') of + Nothing -> False + Just HRefl -> x' == y' && MkSome2 xs' == MkSome2 ys' + (_, _) -> False + +instance Eq (f k) => Eq (EList (HasIs k f)) where + ex == ey = + with2 ex \x -> with2 ey \y -> + case (x, y) of + (HNil, HNil) -> True + (HCons (Proves x') xs', HCons (Proves y') ys') -> + (x' == y') && MkSome2 xs' == MkSome2 ys' + (_, _) -> False + +instance + ( forall x. Eq x => Eq (f x) + , Typeable f + ) + => Eq (Some (Has Typeable (Has Eq f))) + where + MkSome (Proves (Proves x1)) == MkSome (Proves (Proves x2)) = + case eqTypeRep (typeOf x1) (typeOf x2) of + Just HRefl -> x1 == x2 + Nothing -> False + +instance + ( forall x. Ord x => Ord (f x) + , Typeable f + , Eq (Some (Has Typeable (Has Ord f))) + ) + => Ord (Some (Has Typeable (Has Ord f))) + where + MkSome (Proves (Proves x1)) `compare` MkSome (Proves (Proves x2)) = + case eqTypeRep (typeOf x1) (typeOf x2) of + Just HRefl -> x1 `compare` x2 + Nothing -> SomeTypeRep (typeOf x1) `compare` SomeTypeRep (typeOf x2) diff --git a/src/Data/HTree/Families.hs b/src/Data/HTree/Families.hs new file mode 100644 --- /dev/null +++ b/src/Data/HTree/Families.hs @@ -0,0 +1,69 @@ +{-# LANGUAGE UndecidableInstances #-} +{-# LANGUAGE UndecidableSuperClasses #-} + +-- | generic types and type families used in some of the modules +module Data.HTree.Families + ( All + , AllC + , AllInv + , Both + , Not + , Top + , type (++) + , type (||) + ) +where + +import Data.Kind (Constraint) + +-- | like 'Prelude.(++)' on the value level but on the type level +type (++) :: forall k. [k] -> [k] -> [k] +type family xs ++ ys where + '[] ++ ys = ys + (x : xs) ++ ys = x : xs ++ ys + +-- | typelevel Or +type (||) :: Bool -> Bool -> Bool +type family a || b where + 'True || b = 'True + 'False || b = b + +-- | like All but can be partially applied +type AllC :: forall k. (k -> Constraint) -> [k] -> Constraint +class All c xs => AllC c xs + +instance All c xs => AllC c xs + +-- | for all elements of a list, a contraint holds +type All :: forall k. (k -> Constraint) -> [k] -> Constraint +type family All c xs where + All c '[] = () + All c (x : xs) = (c x, All c xs) + +-- | the class that every type has an instance for +type Top :: k -> Constraint +class Top k + +instance Top k + +-- | like 'not' but on the type level +type Not :: Bool -> Bool +type family Not a where + Not 'True = 'False + Not 'False = 'True + +infixr 5 ++ + +-- | 'All' but inversed: holds if all constraints in the list hold +type AllInv :: [k -> Constraint] -> k -> Constraint +class AllInv l k + +instance AllInv '[] k + +instance (c k, AllInv cs k) => AllInv (c ': cs) k + +-- | product of two classes +type Both :: (k -> Constraint) -> (k -> Constraint) -> k -> Constraint +class (c1 a, c2 a) => Both c1 c2 a + +instance (c1 a, c2 a) => Both c1 c2 a diff --git a/src/Data/HTree/Labeled.hs b/src/Data/HTree/Labeled.hs new file mode 100644 --- /dev/null +++ b/src/Data/HTree/Labeled.hs @@ -0,0 +1,178 @@ +{-# LANGUAGE UndecidableInstances #-} +{-# OPTIONS_GHC -Wno-orphans #-} + +-- | This module implements a search in a typelevel tree +-- and offers a handy interface via @-XOverloaedRecordDot@ and 'GHC.Records.HasField'. +-- We can search in the tree via BFS or DFS. +-- Performance wise this doesn't make a difference, as the search is performed at +-- compile time anyway however, it can change the semantics if the tree contains an +-- element more than once, see the example in 'getElem'. +module Data.HTree.Labeled + ( -- * Interface + + -- ** Labeled types + Labeled (..) + , pattern HNodeL + , pattern HLeafL + , type TyNodeL + + -- ** Getting elements + , getElem + , getElem' + , SearchStrategy (..) + + -- ** Reexports + , HasField (..) + , Proxy (..) + + -- * Internal + , HasField' (..) + , Decide (..) + , Elem + , AnyElem + , getElemWithPath + ) +where + +import Data.HTree.Families (Not, type (||)) +import Data.HTree.List (HList (HCons, HNil)) +import Data.HTree.Tree (HForest, HTree (HNode), Path (Deeper, Farther, Here), TyForest, TyTree (TyNode)) +import Data.Kind (Constraint, Type) +import Data.Proxy (Proxy (Proxy)) +import GHC.Generics (Generic) +import GHC.Records (HasField (getField)) + +-- | a type syonym that allows for easy construction of TyTrees that have labeled nodes +type TyNodeL l a = 'TyNode (Labeled l a) + +-- | a pattern that allows for direct construction and destruction of nodes with +-- labels +pattern HNodeL :: forall l a f ts. Functor f => f a -> HForest f ts -> HTree f ('TyNode (Labeled l a) ts) +pattern HNodeL x ts <- (HNode (fmap unLabel -> x) ts) + where + HNodeL x ts = HNode (MkLabeled <$> x) ts + +{-# COMPLETE HNodeL #-} + +-- | a labeled HNode Leaf +pattern HLeafL :: forall l a f. Functor f => f a -> HTree f ('TyNode (Labeled l a) '[]) +pattern HLeafL x <- (HNode (fmap unLabel -> x) HNil) + where + HLeafL x = HNode (MkLabeled <$> x) HNil + +-- | a newtype that is labeled with some typelevel tag +type Labeled :: forall l. l -> Type -> Type +newtype Labeled l a = MkLabeled {unLabel :: a} + deriving stock (Show, Eq, Ord, Functor, Foldable, Traversable, Generic) + +-- | gets an element given a path into the tree +getElemWithPath :: forall typ t f. Path typ t -> HTree f t -> f typ +getElemWithPath Here (HNode e _) = e +getElemWithPath (Farther pt) (HNode e (_ `HCons` ts)) = getElemWithPath pt (HNode e ts) +getElemWithPath (Deeper pt) (HNode _ (t `HCons` _)) = getElemWithPath pt t + +-- | searches a tree for an element and returns that element +getElem' :: forall {proxy} strat typ t f. HasField' (strat :: SearchStrategy) typ t => proxy strat -> HTree f t -> f typ +getElem' _ = getElemWithPath (evidence @strat @typ @t Proxy) + +-- | searches a tree for an element and returns that element, specialised to 'Labeled' and unwraps +-- +-- >>> import Data.Functor.Identity +-- >>> type T = TyNodeL "top" Int [ TyNodeL "inter" Int '[ TyNodeL "foo" Int '[]], TyNodeL "foo" Int '[]] +-- >>> t :: HTree Identity T = 42 `HNodeL` HNodeL 4 (HNodeL 69 HNil `HCons` HNil) `HCons` HNodeL 67 HNil `HCons` HNil +-- >>> getElem @'DFS @"foo" @Int Proxy t +-- Identity 69 +-- >>> getElem @'BFS @"foo" @Int Proxy t +-- Identity 67 +getElem + :: forall {proxy} strat l typ t f + . ( HasField' (strat :: SearchStrategy) (Labeled l typ) t + , Functor f + ) + => proxy strat + -> HTree f t + -> f typ +getElem _ = fmap unLabel . getElemWithPath (evidence @strat @(Labeled l typ) @t Proxy) + +-- the default behaviour is a breadth first search +instance (HasField' 'BFS (Labeled l typ) t, Functor f) => HasField l (HTree f t) (f typ) where + getField = getElem @'BFS @l @typ @t Proxy + +-- | simple typelevel predicate that tests whether some element is in a tree +type Elem :: forall k. k -> TyTree k -> Bool +type family Elem typ t where + Elem a ('TyNode a ts) = 'True + Elem a ('TyNode a' ts) = AnyElem a ts + Elem a t = 'False + +-- | typelevel predicate that tests whether the element is in any of the +-- subtrees +type AnyElem :: forall k. k -> TyForest k -> Bool +type family AnyElem typ ts where + AnyElem a (t : ts) = Elem a t || AnyElem a ts + AnyElem a '[] = 'False + +-- | the search strategy used in 'HasField'', this is intended to be used only as a DataKind +type SearchStrategy :: Type +data SearchStrategy = DFS | BFS + +-- | This is the helper class that creates evidence, +-- it implements a DFS together with Decide +type HasField' :: SearchStrategy -> Type -> TyTree Type -> Constraint +class HasField' strat typ t | strat t -> typ where + evidence :: forall {proxy}. proxy strat -> Path typ t + +-- | Together with HasField' implements a DFS in the tree +type Decide :: SearchStrategy -> Bool -> Type -> TyTree Type -> Constraint +class Decide strat elem typ t | strat t -> typ where + evidence' :: forall {proxy :: forall k. k -> Type}. proxy strat -> proxy elem -> Path typ t + +instance HasField' 'DFS typ ('TyNode typ (t : ts)) where + evidence _ = Here + +instance HasField' 'BFS typ ('TyNode typ (t : ts)) where + evidence _ = Here + +instance HasField' 'DFS typ ('TyNode typ '[]) where + evidence _ = Here + +instance HasField' 'BFS typ ('TyNode typ '[]) where + evidence _ = Here + +instance + {-# OVERLAPPABLE #-} + Decide + 'BFS + (AnyElem typ ts) + typ + ('TyNode typ' (t : ts)) + => HasField' 'BFS typ ('TyNode typ' (t : ts)) + where + evidence _ = evidence' @'BFS @(AnyElem typ ts) @typ @('TyNode typ' (t : ts)) Proxy Proxy + +instance + {-# OVERLAPPABLE #-} + Decide + 'DFS + (Not (Elem typ t)) + typ + ('TyNode typ' (t : ts)) + => HasField' 'DFS typ ('TyNode typ' (t : ts)) + where + evidence _ = evidence' @'DFS @(Not (Elem typ t)) @typ @('TyNode typ' (t : ts)) Proxy Proxy + +instance + HasField' strat typ t + => Decide strat 'False typ ('TyNode typ' (t : ts')) + where + evidence' _ _ = Deeper (evidence @strat @typ @t Proxy) + +instance + HasField' strat typ ('TyNode typ' ts) + => Decide strat 'True typ ('TyNode typ' (t' : ts)) + where + evidence' _ _ = Farther (evidence @strat @typ @('TyNode typ' ts) Proxy) + +infixr 4 `HNodeL` + +infixr 4 `TyNodeL` diff --git a/src/Data/HTree/List.hs b/src/Data/HTree/List.hs new file mode 100644 --- /dev/null +++ b/src/Data/HTree/List.hs @@ -0,0 +1,111 @@ +{-# OPTIONS_GHC -Wno-unrecognised-pragmas #-} + +{-# HLINT ignore "Eta reduce" #-} + +-- | implements a heterogeneous list to use for forests of heterogeneous trees +module Data.HTree.List + ( -- * heterogeneous list + HList ((:::), HSing, ..) + + -- * mapping + , hcmap + , hmap + + -- * traversing + , htraverse + , hctraverse + + -- * folding + , hcFold + + -- * helpers + , allTopHList + , hconcat + ) +where + +import Data.Functor.Identity (Identity (Identity, runIdentity)) +import Data.HTree.Constraint (withDict, pattern Dict, type Dict) +import Data.HTree.Families (All, Top, type (++)) +import Data.Kind (Type) + +-- | A heterogeneous list +-- +-- >>> "bla" `HCons` 23 `HCons` HNil :: HList Identity '[ String, Int ] +-- HCons (Identity "bla") (HCons (Identity 23) HNil) +type HList :: forall k. (k -> Type) -> [k] -> Type +data HList f ts where + HCons :: forall f x xs. f x -> HList f xs -> HList f (x : xs) + HNil :: forall f. HList f '[] + +-- | pattern synonym for 'HCons' +-- +-- >>> t = "bla" ::: 23 ::: HNil :: HList Identity '[ String, Int ] +-- >>> t +-- HCons (Identity "bla") (HCons (Identity 23) HNil) +-- >>> case t of (x ::: _) -> runIdentity x +-- "bla" +pattern (:::) :: forall f x xs. f x -> HList f xs -> HList f (x : xs) +pattern x ::: xs = HCons x xs + +-- | pattern that allows to construct a singleton HList +-- +-- >>> HSing 42 :: HList Identity '[ Int ] +-- HCons (Identity 42) HNil +pattern HSing :: forall f a. f a -> HList f '[a] +pattern HSing x = HCons x HNil + +-- | map with a function that maps forall f a +hmap :: forall f g xs. (forall a. f a -> g a) -> HList f xs -> HList g xs +hmap f l = withDict (allTopHList l) $ hcmap @Top @f @g f l + +-- | map with a constraint that holds for all elements of the list +-- +-- >>> import Data.Functor.Const +-- >>> hcmap @Show (Const . show . runIdentity) (42 `HCons` HSing "bla" :: HList Identity '[ Int, String ]) +-- HCons (Const "42") (HCons (Const "\"bla\"") HNil) +hcmap :: forall c f g xs. All c xs => (forall a. c a => f a -> g a) -> HList f xs -> HList g xs +hcmap f = runIdentity . hctraverse @c @Identity @f @g (Identity . f) + +-- | traverse a structure with a function +htraverse :: forall t f g xs. Applicative t => (forall a. f a -> t (g a)) -> HList f xs -> t (HList g xs) +htraverse f l = withDict (allTopHList l) $ hctraverse @Top @t @f @g f l + +-- | traverse a structure such that a constraint holds; this is the workhorse of mapping and traversing +-- +-- >>> import Data.Functor.Const +-- >>> hctraverse @Show (Just . Const . show . runIdentity) (42 `HCons` HSing "bla" :: HList Identity '[ Int, String ]) +-- Just (HCons (Const "42") (HCons (Const "\"bla\"") HNil)) +hctraverse :: forall c t f g xs. (All c xs, Applicative t) => (forall a. c a => f a -> t (g a)) -> HList f xs -> t (HList g xs) +hctraverse _ HNil = pure HNil +hctraverse f (HCons x xs) = HCons <$> f x <*> hctraverse @c @t @f @g f xs + +-- | foldr for HLists. +hcFold :: forall c f b xs. All c xs => (forall a. c a => f a -> b -> b) -> b -> HList f xs -> b +hcFold _ def HNil = def +hcFold f def (x `HCons` xs) = f x $ hcFold @c f def xs + +-- | witnesses that for all HLists, we can always derive the All Top constraint +allTopHList :: forall f xs. HList f xs -> Dict (All Top xs) +allTopHList HNil = Dict +allTopHList (HCons _ xs) = case allTopHList xs of + Dict -> Dict + +-- | concats two heterogeneous lists +hconcat :: forall f xs ys. HList f xs -> HList f ys -> HList f (xs ++ ys) +hconcat HNil ys = ys +hconcat (x `HCons` xs) ys = x `HCons` xs `hconcat` ys + +infixr 5 `HCons` + +infixr 5 ::: + +infixr 5 `hconcat` + +deriving stock instance Show (HList f '[]) + +deriving stock instance (Show (f x), Show (HList f xs)) => Show (HList f (x : xs)) + +deriving stock instance Eq (HList f '[]) + +deriving stock instance (Eq (f x), Eq (HList f xs)) => Eq (HList f (x : xs)) diff --git a/src/Data/HTree/Tree.hs b/src/Data/HTree/Tree.hs new file mode 100644 --- /dev/null +++ b/src/Data/HTree/Tree.hs @@ -0,0 +1,253 @@ +{-# LANGUAGE UndecidableInstances #-} +{-# LANGUAGE UndecidableSuperClasses #-} +{-# OPTIONS_GHC -Wno-unrecognised-pragmas #-} + +{-# HLINT ignore "Eta reduce" #-} + +-- | implements a heterogeneous tree ('HTree') indexed by a homogeneous type level tree ('TyTree') +module Data.HTree.Tree + ( -- * type level tree + TyTree (..) + , TyForest + + -- * heterogeneous tree + , HTree (HLeaf, ..) + , HForest + + -- * mapping + + -- ** value level + , hmap + , hcmap + + -- * type level + , TreeMap + , ForestMap + + -- * traversing + , htraverse + , hctraverse + + -- * folding + + -- ** value level + , hFoldMap + , hcFoldMap + , hFlatten + + -- ** type level + , FlattenTree + , FlattenForest + + -- * paths into the htree and things you can do with those + , Path (..) + , replaceAt + + -- * helpful constraints + , AllTree + , AllTreeC + , AllForest + + -- ** helpers for witnessing the constraints + , allTopHTree + , allTopHForest + ) +where + +import Data.Functor.Identity (Identity (Identity, runIdentity)) +import Data.HTree.Constraint (Dict, withDict, pattern Dict) +import Data.HTree.Families (All, Top, type (++)) +import Data.HTree.List (HList (HCons, HNil), hconcat) +import Data.HTree.List qualified as L +import Data.Kind (Constraint, Type) + +-- | a type level rose-tree that is only intended to +-- store something of a certain kind, e.g. Type +type TyTree :: forall k. k -> Type +data TyTree k where + TyNode :: forall a. a -> TyForest a -> TyTree a + +-- | a forest of TyTrees +type TyForest :: forall k. k -> Type +type TyForest a = [TyTree a] + +-- | a heterogeneous rose tree indexed by a TyTree +type HTree :: forall k. (k -> Type) -> TyTree k -> Type +data HTree f t where + HNode :: forall f a ts. f a -> HForest f ts -> HTree f ('TyNode a ts) + +-- | a pattern synonym for the leaf of an HTree +pattern HLeaf :: forall f a. forall. f a -> HTree f ('TyNode a '[]) +pattern HLeaf a = HNode a HNil + +-- | A forest of heterogeneous rose trees +type HForest :: forall k. (k -> Type) -> TyForest k -> Type +type HForest f ts = HList (HTree f) ts + +-- | map a function over an HTree +hmap + :: forall {k} (f :: k -> Type) (g :: k -> Type) (t :: TyTree k) + . (forall a. f a -> g a) + -> HTree f t + -> HTree g t +hmap f t = withDict (allTopHTree t) $ hcmap @Top @f @g f t + +-- | map a function with a constraint over an HTree +hcmap + :: forall + {k} + (c :: k -> Constraint) + (f :: k -> Type) + (g :: k -> Type) + (t :: TyTree k) + . AllTree c t + => (forall a. c a => f a -> g a) + -> HTree f t + -> HTree g t +hcmap f = runIdentity . hctraverse @c @Identity @f @g (Identity . f) + +-- | traverse a structure with a function +htraverse + :: forall + {k} + (h :: Type -> Type) + (f :: k -> Type) + (g :: k -> Type) + (t :: TyTree k) + . Applicative h + => (forall a. f a -> h (g a)) + -> HTree f t + -> h (HTree g t) +htraverse f t = withDict (allTopHTree t) $ hctraverse @Top f t + +-- | traverse a structure such that a constraint holds; this is the workhorse of mapping and traversing +hctraverse + :: forall + {k} + (c :: k -> Constraint) + (h :: Type -> Type) + (f :: k -> Type) + (g :: k -> Type) + (t :: TyTree k) + . (AllTree c t, Applicative h) + => (forall a. c a => f a -> h (g a)) + -> HTree f t + -> h (HTree g t) +hctraverse f (HNode x ts) = HNode <$> f x <*> L.hctraverse @(AllTreeC c) @h @(HTree f) @(HTree g) (hctraverse @c f) ts + +-- | map a functor over a TyTree +type TreeMap :: forall k l. (k -> l) -> TyTree k -> TyTree l +type family TreeMap f t where + forall f x. TreeMap f ('TyNode x '[]) = 'TyNode (f x) '[] + forall f x xs. TreeMap f ('TyNode x xs) = 'TyNode (f x) (ForestMap f xs) + +-- | map a functor over a TyForest +type ForestMap :: forall k l. (k -> l) -> TyForest k -> TyForest l +type family ForestMap f t where + ForestMap _ '[] = '[] + forall f n ns. ForestMap f (n : ns) = TreeMap f n : ForestMap f ns + +-- | monoidally folds down a tree to a single value using a constraint on +-- the element in the wrapping functor, this is similar to 'foldMap' +hcFoldMap + :: forall + {k} + (c :: k -> Constraint) + (f :: k -> Type) + (t :: TyTree k) + (b :: Type) + . (AllTree c t, Semigroup b) + => (forall a. c a => f a -> b) + -> HTree f t + -> b +hcFoldMap f (HNode x HNil) = f x +hcFoldMap f (HNode x (y `HCons` ys)) = hcFoldMap @c f y <> hcFoldMap @c f (HNode x ys) + +-- | monoidally folds down a tree to a single value, this is similar to 'foldMap' +hFoldMap + :: forall + {k} + (f :: k -> Type) + (t :: TyTree k) + (b :: Type) + . Semigroup b + => (forall a. f a -> b) + -> HTree f t + -> b +hFoldMap f t = withDict (allTopHTree t) $ hcFoldMap @Top f t + +-- | flatten a heterogeneous tree down to a heterogeneous list +hFlatten + :: forall + {k} + (f :: k -> Type) + (t :: TyTree k) + . HTree f t + -> HList f (FlattenTree t) +hFlatten (HNode x xs) = x `HCons` hflattenForest xs + where + hflattenForest :: forall ts. HForest f ts -> HList f (FlattenForest ts) + hflattenForest HNil = HNil + hflattenForest (y `HCons` ys) = hFlatten y `hconcat` hflattenForest ys + +-- | a type family that flattens a tree down to a list +type FlattenTree :: forall k. TyTree k -> [k] +type family FlattenTree t where + forall x xs. FlattenTree ('TyNode x xs) = x : FlattenForest xs + +-- | a type family that flattens a forest down to a list +type FlattenForest :: forall k. TyForest k -> [k] +type family FlattenForest f where + FlattenForest '[] = '[] + FlattenForest (x : xs) = FlattenTree x ++ FlattenForest xs + +-- | a constraint holds for all elements in the tree +type AllTree :: forall k. (k -> Constraint) -> TyTree k -> Constraint +type family AllTree c ts where + forall c x ts. AllTree c ('TyNode x ts) = (c x, AllForest c ts) + +-- | constraint synonym for AllTree +type AllTreeC :: forall k. (k -> Constraint) -> TyTree k -> Constraint +class AllTree c ts => AllTreeC c ts + +instance forall c ts. AllTree c ts => AllTreeC c ts + +-- | a constraint holds for all elements in the forest +type AllForest :: forall k. (k -> Constraint) -> TyForest k -> Constraint +type family AllForest c t where + AllForest c xs = All (AllTreeC c) xs + +-- | witnesses that for any HTree the constraint AllTree Top always holds +allTopHTree :: forall f t. HTree f t -> Dict (AllTree Top t) +allTopHTree (HNode _ (allTopHForest -> Dict)) = Dict + +-- | witnesses that for any HForest the constraint AllForest Top always holds +allTopHForest :: forall f t. HForest f t -> Dict (AllForest Top t) +allTopHForest HNil = Dict +allTopHForest (HCons (allTopHTree -> Dict) (allTopHForest -> Dict)) = Dict + +-- | replace an element at a certain path. +replaceAt :: Path typ t -> f typ -> HTree f t -> HTree f t +replaceAt Here x (HNode _ xs) = HNode x xs +replaceAt (Deeper pt) x (HNode y (t `HCons` ts)) = HNode y (replaceAt pt x t `HCons` ts) +replaceAt (Farther pt) x (HNode y (t `HCons` ts)) = let HNode y' ts' = replaceAt pt x (HNode y ts) in HNode y' (t `HCons` ts') + +-- | provides evidence that an element is in the tree by +-- providing a path to the element +type Path :: forall k. k -> TyTree k -> Type +data Path k t where + Here :: forall a ts. Path a ('TyNode a ts) + Deeper :: forall a b t ts. Path a t -> Path a ('TyNode b (t : ts)) + Farther :: forall a b t ts. Path a ('TyNode b ts) -> Path a ('TyNode b (t : ts)) + +infixr 4 `HNode` + +infixr 4 `TyNode` + +deriving stock instance (Show (f a), Show (HForest f t)) => Show (HTree f ('TyNode a t)) + +deriving stock instance (Eq (f a), Eq (HForest f t)) => Eq (HTree f ('TyNode a t)) + +deriving stock instance Show (Path typ t) + +deriving stock instance Eq (Path typ t) diff --git a/test/Main.hs b/test/Main.hs new file mode 100644 --- /dev/null +++ b/test/Main.hs @@ -0,0 +1,12 @@ +module Main (main) where + +import Spec.HTree.Fold qualified as Fold +import Spec.HTree.Labeled qualified as Labeled +import Spec.HTree.Traverse qualified as Traverse +import Test.Hspec (hspec) + +main :: IO () +main = hspec do + Labeled.spec + Traverse.spec + Fold.spec diff --git a/test/Spec/HTree/Fixtures.hs b/test/Spec/HTree/Fixtures.hs new file mode 100644 --- /dev/null +++ b/test/Spec/HTree/Fixtures.hs @@ -0,0 +1,187 @@ +module Spec.HTree.Fixtures + ( type ExL + , exL + , type Ex + , ex + , exShown + , exC + , type ExReal + , exReal + , type I + , pattern I + , unI + , type K + , pattern K + , unK + , type ExIntegral + , exIntegral + , type ExBfsDfs + , exBfsDfs + ) +where + +import Data.Functor.Const (Const (Const, getConst)) +import Data.Functor.Identity (Identity (Identity, runIdentity)) +import Data.HTree.Labeled (pattern HNodeL, type TyNodeL) +import Data.HTree.List (HList (HNil, HSing, (:::))) +import Data.HTree.Tree (HTree (HLeaf, HNode), TyTree (TyNode)) +import Data.Tree (Tree (Node)) + +type K = Const + +pattern K :: forall a b. a -> K a b +pattern K a = Const a + +unK :: forall a b. K a b -> a +unK = getConst + +type I = Identity + +pattern I :: forall a. a -> I a +pattern I a = Identity a + +unI :: forall a. I a -> a +unI = runIdentity + +type ExL = + TyNodeL + "top" + Int + [ TyNodeL + "b" + Int + [ TyNodeL "c" Int '[] + , TyNodeL "d" Bool '[] + , TyNodeL + "e" + String + '[ TyNodeL "bla" Int '[] + ] + ] + , TyNodeL "a" Int '[] + ] + +exL :: HTree Identity ExL +exL = + HNodeL 5 do + HNodeL 12 do + HNodeL 13 HNil + ::: HNodeL (I False) HNil + ::: HNodeL "test" (HNodeL 9 HNil ::: HNil) + ::: HNil + ::: HNodeL 42 HNil + ::: HNil + +type Ex = + TyNode + Int + [ TyNode + Int + [ TyNode Int '[] + , TyNode Bool '[] + , TyNode String '[ 'TyNode Int '[]] + ] + , 'TyNode Int '[] + ] + +ex :: HTree Identity Ex +ex = + HNode 5 do + HNode 12 do + HNode 13 HNil + ::: HNode (I False) HNil + ::: HNode "test" (HNode 9 HNil ::: HNil) + ::: HNil + ::: HNode 43 HNil + ::: HNil + +exShown :: Tree String +exShown = + Node + "5" + [ Node + "12" + [Node "13" [], Node "False" [], Node "\"test\"" [Node "9" []]] + , Node "43" [] + ] + +exC :: HTree (K Int) Ex +exC = + HNode 5 do + HNode 12 do + HNode 13 HNil + ::: HNode 13 HNil + ::: HNode 5 (HNode 9 HNil ::: HNil) + ::: HNil + ::: HNode 43 HNil + ::: HNil + +type ExReal = + 'TyNode + Int + '[ 'TyNode + Float + '[ 'TyNode Double '[] + , 'TyNode Float '[] + , 'TyNode + Integer + '[ 'TyNode Float '[]] + ] + , 'TyNode + Int + '[ 'TyNode Float '[]] + ] + +exReal :: HTree I ExReal +exReal = + HNode 42 do + HNode 2.7 do + HLeaf 13.7 + ::: HLeaf 12.2 + ::: HSing do + HNode 14 do + HSing (HLeaf (I 12.7)) + ::: HNode 12 do HSing (HLeaf 3.14) + ::: HNil + +type ExIntegral = + 'TyNode + Int + [ TyNode + Integer + '[ TyNode Int '[] + , TyNode Integer '[] + , TyNode + Integer + '[TyNode Int '[]] + ] + , TyNode + Int + '[TyNode Int '[]] + ] + +exIntegral :: HTree I ExIntegral +exIntegral = HNode 42 do + HNode 7 do + HLeaf 13 ::: HLeaf 122 ::: HSing do + HNode 14 (HSing (HLeaf 127)) + ::: HNode 12 (HSing (HLeaf 31)) + ::: HNil + +type ExBfsDfs = + TyNodeL + "top" + Int + [ TyNodeL + "inter" + Int + '[ TyNodeL "foo" Int '[] + ] + , TyNodeL "foo" Int '[] + ] + +exBfsDfs :: HTree I ExBfsDfs +exBfsDfs = HNodeL 42 do + HNodeL 4 (HSing (HNodeL 69 HNil)) + ::: HNodeL 67 HNil + ::: HNil diff --git a/test/Spec/HTree/Fold.hs b/test/Spec/HTree/Fold.hs new file mode 100644 --- /dev/null +++ b/test/Spec/HTree/Fold.hs @@ -0,0 +1,71 @@ +module Spec.HTree.Fold (spec) where + +import Data.Functor.Identity (Identity) +import Data.HTree (hcFoldMap) +import Data.HTree.Existential (Has (Proves), Some (MkSome), hcFoldEHList, hcFoldMapEHTree) +import Data.Semigroup (Product (Product, getProduct), Sum (Sum, getSum)) +import Data.Set (Set, empty, insert, singleton) +import Data.Tree (Tree) +import Data.Typeable (Typeable, typeOf) +import GHC.Real ((%)) +import Spec.HTree.Fixtures (exIntegral, exReal) +import Spec.HTree.Orphans (toEList, toETree) +import Test.Hspec (Spec, describe, it) +import Test.Hspec.QuickCheck (modifyMaxSuccess, prop) +import Test.QuickCheck (Property, (===)) + +spec :: Spec +spec = do + describe "folding an HTree of numbers" do + it "calculates the correct sum" (31649046316921651 % 281474976710656 == getSum (hcFoldMap @Real (Sum . toRational) exReal)) + it "calculates the correct product" (308407698144 == getProduct (hcFoldMap @Integral (Product . toInteger) exIntegral)) + modifyMaxSuccess (* 10) do + prop "yields the same results as expected for many Lists" $ + foldsSameList @Identity + prop "yields the same results as expected for many trees" $ + foldsSameTree @Identity + +foldsSameList + :: forall f + . ( forall x. Eq x => Eq (f x) + , forall x. Ord x => Ord (f x) + , Typeable f + , Applicative f + ) + => [Some (Has Typeable (Has Ord f))] + -> Property +foldsSameList l = + let folded :: Set (String, Some (Has Typeable (Has Ord f))) + folded = + foldMap + (\(MkSome (Proves f)) -> singleton (show (typeOf f), MkSome (Proves f))) + l + hfolded :: Set (String, Some (Has Typeable (Has Ord f))) + hfolded = + hcFoldEHList @Typeable + (\f acc -> (show (typeOf f), MkSome (Proves f)) `insert` acc) + empty + (toEList l) + in folded === hfolded + +foldsSameTree + :: forall f + . ( forall x. Eq x => Eq (f x) + , forall x. Ord x => Ord (f x) + , Typeable f + , Applicative f + ) + => Tree (Some (Has Typeable (Has Ord f))) + -> Property +foldsSameTree l = + let folded :: Set (String, Some (Has Typeable (Has Ord f))) + folded = + foldMap + (\(MkSome (Proves f)) -> singleton (show (typeOf f), MkSome (Proves f))) + l + hfolded :: Set (String, Some (Has Typeable (Has Ord f))) + hfolded = + hcFoldMapEHTree @Typeable + (\f -> singleton (show (typeOf f), MkSome (Proves f))) + (toETree l) + in folded === hfolded diff --git a/test/Spec/HTree/Helpers.hs b/test/Spec/HTree/Helpers.hs new file mode 100644 --- /dev/null +++ b/test/Spec/HTree/Helpers.hs @@ -0,0 +1,18 @@ +module Spec.HTree.Helpers (forgetHTree, forgetHList, liftedWith) where + +import Data.Functor.Const (Const (Const, getConst)) +import Data.HTree.Existential (Some (MkSome)) +import Data.HTree.List (HList (HCons, HNil), hmap) +import Data.HTree.Tree (HTree (HNode)) +import Data.Kind (Type) +import Data.Tree (Tree (Node)) + +forgetHTree :: forall a t. HTree (Const a) t -> Tree a +forgetHTree (HNode x ts) = Node (getConst x) (forgetHList (hmap (Const . forgetHTree) ts)) + +forgetHList :: forall a l. HList (Const a) l -> [a] +forgetHList HNil = [] +forgetHList (HCons x xs) = getConst x : forgetHList xs + +liftedWith :: forall {l} (g :: l -> Type) f r. Functor f => f (Some g) -> (forall m. g m -> r) -> f r +liftedWith a f = fmap \case { MkSome b -> f b } a diff --git a/test/Spec/HTree/Labeled.hs b/test/Spec/HTree/Labeled.hs new file mode 100644 --- /dev/null +++ b/test/Spec/HTree/Labeled.hs @@ -0,0 +1,25 @@ +{-# LANGUAGE OverloadedRecordDot #-} +{-# OPTIONS_GHC -fprint-potential-instances -fprint-typechecker-elaboration #-} + +module Spec.HTree.Labeled (spec) where + +import Data.HTree.Labeled (Proxy (Proxy), SearchStrategy (BFS, DFS), getElem) +import Spec.HTree.Fixtures (exBfsDfs, exL, unI) +import Test.Hspec (Spec, describe, it) + +spec :: Spec +spec = describe "elements in the example get returned as expected" do + it "has top node 5" do + (5 :: Int) == unI exL.top + it "has a node 42" do + (42 :: Int) == unI exL.a + it "has bla node 9" do + (9 :: Int) == unI exL.bla + it "has d node False" do + not $ unI exL.d + it "has e node \"test\"" do + ("test" :: String) == unI exL.e + it "finds int via BFS" do + unI (getElem @BFS @"foo" @Int Proxy exBfsDfs) == 67 + it "finds int via DFS" do + unI (getElem @DFS @"foo" @Int Proxy exBfsDfs) == 69 diff --git a/test/Spec/HTree/Orphans.hs b/test/Spec/HTree/Orphans.hs new file mode 100644 --- /dev/null +++ b/test/Spec/HTree/Orphans.hs @@ -0,0 +1,64 @@ +{-# LANGUAGE ImpredicativeTypes #-} +{-# LANGUAGE PartialTypeSignatures #-} +{-# LANGUAGE TemplateHaskell #-} +{-# LANGUAGE UndecidableInstances #-} +{-# LANGUAGE NoOverloadedLists #-} +{-# OPTIONS_GHC -Wno-orphans #-} + +module Spec.HTree.Orphans where + +import Data.HTree (HTree (HNode)) +import Data.HTree.Existential (EList, ETree, Has (Proves), Some (MkSome), Some2 (MkSome2)) +import Data.HTree.Families (Both) +import Data.HTree.List (HList (HCons, HNil)) +import Data.Maybe (catMaybes) +import Data.Proxy (Proxy (Proxy)) +import Data.Tree (Tree (Node)) +import Spec.HTree.Helpers (liftedWith) +import Spec.HTree.TH (discoverInstancesTypeable) +import Test.QuickCheck.Arbitrary (Arbitrary (arbitrary)) +import Test.QuickCheck.Gen (Gen, oneof) +import Test.QuickCheck.Instances () +import Type.Reflection (Typeable, eqTypeRep, typeRep, (:~~:) (HRefl)) + +embedType :: [Some (Has Typeable Gen)] +embedType = liftedWith $$(discoverInstancesTypeable @Arbitrary) \(Proves (Proxy :: Proxy a)) -> + MkSome $ Proves $ arbitrary @a + +embedArbOrd :: [Some (Has (Both Typeable Ord) Gen)] +embedArbOrd = + catMaybes $ concat $ liftedWith $$(discoverInstancesTypeable @Ord) \(Proves (Proxy :: Proxy a)) -> + liftedWith $$(discoverInstancesTypeable @Arbitrary) \(Proves (Proxy :: Proxy b)) -> + case eqTypeRep (typeRep @a) (typeRep @b) of + Nothing -> Nothing + Just HRefl -> Just (MkSome (Proves $ arbitrary @a)) + +toEList :: [Some x] -> EList x +toEList [] = MkSome2 HNil +toEList (MkSome x : xs) = + case toEList xs of + MkSome2 t -> MkSome2 (HCons x t) + +toETree :: Tree (Some f) -> ETree f +toETree (Node (MkSome t) []) = MkSome2 (HNode t HNil) +toETree (Node t' (t : ts)) = + case (toETree t, toETree (Node t' ts)) of + (MkSome2 ht, MkSome2 (HNode ht' hts)) -> MkSome2 (HNode ht' (HCons ht hts)) + +instance Applicative f => Arbitrary (EList (Has Typeable f)) where + arbitrary = toEList <$> arbitrary + +instance Applicative f => Arbitrary (ETree (Has Typeable f)) where + arbitrary = toETree <$> arbitrary + +instance Applicative f => Arbitrary (Some (Has Typeable f)) where + arbitrary = oneof $ liftedWith embedType \(Proves gen :: Has Typeable Gen b) -> + MkSome . Proves . pure <$> gen + +instance {-# OVERLAPPING #-} Applicative f => Arbitrary (Some (Has Typeable (Has Ord f))) where + arbitrary = oneof $ liftedWith embedArbOrd \(Proves gen :: Has (Both Typeable Ord) Gen b) -> + MkSome . Proves . Proves . pure <$> gen + +instance (forall x. Eq x => Eq (f x), Typeable f) => Eq (Some (Has Typeable (Has Ord f))) where + MkSome (Proves (Proves x)) == MkSome (Proves (Proves y)) = + MkSome (Proves @Typeable (Proves @Eq x)) == MkSome (Proves @Typeable (Proves @Eq y)) diff --git a/test/Spec/HTree/TH.hs b/test/Spec/HTree/TH.hs new file mode 100644 --- /dev/null +++ b/test/Spec/HTree/TH.hs @@ -0,0 +1,103 @@ +{-# LANGUAGE ImpredicativeTypes #-} +{-# LANGUAGE TemplateHaskell #-} +{-# LANGUAGE NoOverloadedLists #-} +{-# OPTIONS_GHC -fno-print-explicit-runtime-reps #-} + +-- | adapated from 'discoverInstances' from https://hackage.haskell.org/package/discover-instances-0.1.0.0 +module Spec.HTree.TH (discoverInstances, discoverInstancesTypeable) where + +import Data.HTree.Existential (Has (Proves), Some (MkSome)) +import Data.HTree.Families (Both) +import Data.Kind (Constraint) +import Data.Proxy (Proxy (Proxy)) +import Data.Typeable (Typeable, typeRep) +import Language.Haskell.TH (Type) +import Language.Haskell.TH.Syntax + ( Dec (InstanceD) + , Exp (ListE) + , InstanceDec + , Q + , TExp (TExp, unType) + , Type (..) + , mkName + , reifyInstances + , reportWarning + , unsafeTExpCoerce + ) +import Language.Haskell.TH.Syntax.Compat + ( SpliceQ + , examineSplice + , liftSplice + ) + +discoverInstances :: forall {k} (c :: k -> Constraint). Typeable c => SpliceQ [Some (Has c Proxy)] +discoverInstances = liftSplice $ do + let className = show (typeRep (Proxy @c)) + listTE :: [TExp a] -> TExp [a] + listTE = TExp . ListE . map unType + instanceDecs <- reifyInstances (mkName className) [VarT (mkName "a")] + + dicts <- listTE <$> traverse decToDict instanceDecs + + examineSplice [||concat $$(liftSplice $ pure dicts)||] + +decToDict :: forall {k} (c :: k -> Constraint). InstanceDec -> Q (TExp [Some (Has c Proxy)]) +decToDict = \case + InstanceD _moverlap cxt typ _decs -> + case cxt of + [] -> do + let t = case typ of + AppT _ t' -> stripSig t' + _ -> t + stripSig (SigT a _) = a + stripSig x = x + proxy = [|Proxy :: Proxy $(pure t)|] + unsafeTExpCoerce [|[MkSome (Proves $proxy)]|] + _ -> examineSplice [||[]||] + _ -> do + reportWarning "discoverInstances called on 'reifyInstances' somehow returned something that wasn't a type class instance." + examineSplice [||[]||] + +discoverInstancesTypeable :: forall {k} (c :: k -> Constraint). Typeable c => SpliceQ [Some (Has (Both Typeable c) Proxy)] +discoverInstancesTypeable = liftSplice $ do + let className = show (typeRep (Proxy @c)) + listTE :: [TExp a] -> TExp [a] + listTE = TExp . ListE . map unType + instanceDecs <- reifyInstances (mkName className) [VarT (mkName "a")] + + dicts <- listTE <$> traverse decToDictTypeable instanceDecs + + examineSplice [||concat $$(liftSplice $ pure dicts)||] + +decToDictTypeable :: forall {k} (c :: k -> Constraint). InstanceDec -> Q (TExp [Some (Has (Both Typeable c) Proxy)]) +decToDictTypeable = \case + InstanceD _moverlap cxt typ _decs -> + case cxt of + [] -> do + let t :: Maybe Type = clean =<< removeClass typ + removeClass :: Type -> Maybe Type + removeClass (AppT _ x) = pure x + removeClass (SigT x _) = removeClass x + removeClass _ = Nothing + + clean :: Type -> Maybe Type + clean (AppT f x) = AppT <$> clean f <*> clean x + clean (SigT x _) = clean x + clean (VarT _) = Nothing + clean (ConT n) = pure $ ConT n + clean (ParensT n) = pure $ ParensT n + clean (TupleT n) = pure $ TupleT n + clean ListT = pure ListT + clean _ = Nothing + + proxy = case t of + Just t' -> Just [|Proxy :: Proxy $(pure t')|] + Nothing -> Nothing + + unsafeTExpCoerce $ case proxy of + Just proxy' -> [|[MkSome (Proves @(Both Typeable _) $proxy')]|] + Nothing -> [|[]|] + _ -> examineSplice [||[]||] + _ -> do + reportWarning "discoverInstances called on 'reifyInstances' somehow returned something that wasn't a type class instance." + examineSplice [||[]||] diff --git a/test/Spec/HTree/Traverse.hs b/test/Spec/HTree/Traverse.hs new file mode 100644 --- /dev/null +++ b/test/Spec/HTree/Traverse.hs @@ -0,0 +1,15 @@ +module Spec.HTree.Traverse (spec) where + +import Data.Functor.Const (Const (Const)) +import Data.HTree.Tree (HTree, hctraverse) +import Spec.HTree.Fixtures (ex, exShown, unI, type Ex) +import Spec.HTree.Helpers (forgetHTree) +import Test.Hspec (Spec, describe, it) + +spec :: Spec +spec = do + describe "use hctraverse" $ do + it "yields the same result as expected" $ do + let traversed :: Maybe (HTree (Const String) Ex) + traversed = hctraverse @Show (Just . Const . show . unI) ex + Just `traverse` exShown == (forgetHTree <$> traversed)