mirror of
https://github.com/yaitskov/purescript-typeable.git
synced 2024-12-27 21:43:05 +00:00
Add Data.Data module
This commit is contained in:
Anupam Jain
parent
e5391fca2b
commit
3ca165ffd6
288
src/Data/Data.purs
Normal file
288
src/Data/Data.purs
Normal file
@ -0,0 +1,288 @@
|
||||
module Data.Data where
|
||||
|
||||
import Control.Alt ((<|>))
|
||||
import Control.Alternative (empty)
|
||||
import Control.Applicative (pure)
|
||||
import Control.Bind (bind, (>>=))
|
||||
import Control.Category (identity, (<<<))
|
||||
import Control.Monad (class Monad)
|
||||
import Control.MonadPlus (class MonadPlus)
|
||||
import Data.Array as A
|
||||
import Data.CommutativeRing ((+))
|
||||
import Data.Const (Const(..))
|
||||
import Data.Eq ((==))
|
||||
import Data.Foldable (foldl)
|
||||
import Data.Function (const, ($))
|
||||
import Data.Identity (Identity(..))
|
||||
import Data.Maybe (Maybe(..), fromMaybe, maybe)
|
||||
import Data.Newtype (unwrap)
|
||||
import Data.Tuple (Tuple(..))
|
||||
import Data.Typeable (class Tag1, class Typeable, cast)
|
||||
import Unsafe.Coerce (unsafeCoerce)
|
||||
|
||||
mkT :: forall a b. Typeable a => Typeable b => (b -> b) -> a -> a
|
||||
mkT f = fromMaybe identity (cast f)
|
||||
|
||||
mkQ :: forall a b r. Typeable a => Typeable b => r -> (b -> r) -> a -> r
|
||||
mkQ r q a = maybe r q (cast a)
|
||||
|
||||
mkM :: forall a b m. Typeable a => Typeable b => Monad m => Tag1 m => (b -> m b) -> a -> m a
|
||||
mkM f = fromMaybe pure (cast f)
|
||||
|
||||
-- Purescript can't have cycles in typeclasses
|
||||
-- So we manually reify the dictionary into the DataDict datatype
|
||||
-- Not using wrapped records here because Purescript can't handle constraints inside records
|
||||
newtype DataDict a = DataDict
|
||||
(forall c. (forall d b. Data d => c (d -> b) -> d -> c b)
|
||||
-- ^ defines how nonempty constructor applications are
|
||||
-- folded. It takes the folded tail of the constructor
|
||||
-- application and its head, i.e., an immediate subterm,
|
||||
-- and combines them in some way.
|
||||
-> (forall g. g -> c g)
|
||||
-- ^ defines how the empty constructor application is
|
||||
-- folded, like the neutral \/ start element for list
|
||||
-- folding.
|
||||
-> a
|
||||
-- ^ structure to be folded.
|
||||
-> c a
|
||||
-- ^ result, with a type defined in terms of @a@, but
|
||||
-- variability is achieved by means of type constructor
|
||||
-- @c@ for the construction of the actual result type.
|
||||
)
|
||||
|
||||
gfoldl :: forall a c. Data a => (forall d b. Data d => c (d -> b) -> d -> c b)
|
||||
-- ^ defines how nonempty constructor applications are
|
||||
-- folded. It takes the folded tail of the constructor
|
||||
-- application and its head, i.e., an immediate subterm,
|
||||
-- and combines them in some way.
|
||||
-> (forall g. g -> c g)
|
||||
-- ^ defines how the empty constructor application is
|
||||
-- folded, like the neutral \/ start element for list
|
||||
-- folding.
|
||||
-> a
|
||||
-- ^ structure to be folded.
|
||||
-> c a
|
||||
-- ^ result, with a type defined in terms of @a@, but
|
||||
-- variability is achieved by means of type constructor
|
||||
-- @c@ for the construction of the actual result type.
|
||||
gfoldl = let DataDict f = dataDict in f
|
||||
|
||||
-- ((forall b. Data b => b -> b) -> a -> a)
|
||||
-- (forall r. (forall b. Data b => b -> r) -> a -> Array r)
|
||||
-- (forall m. (Monad m => (forall b. Data b => b -> m b) -> a -> m a))
|
||||
|
||||
class Typeable a <= Data a where
|
||||
dataDict :: DataDict a
|
||||
|
||||
-- | A generic transformation that maps over the immediate subterms
|
||||
--
|
||||
-- The default definition instantiates the type constructor @c@ in the
|
||||
-- type of 'gfoldl' to an identity datatype constructor, using the
|
||||
-- isomorphism pair as injection and projection.
|
||||
gmapT :: forall a. Data a => (forall b. Data b => b -> b) -> a -> a
|
||||
|
||||
-- Use the Identity datatype constructor
|
||||
-- to instantiate the type constructor c in the type of gfoldl,
|
||||
-- and perform injections Identity and projections runIdentity accordingly.
|
||||
--
|
||||
gmapT f x0 = unwrap (gfoldl k Identity x0)
|
||||
where
|
||||
k :: forall d b. Data d => Identity (d->b) -> d -> Identity b
|
||||
k (Identity c) x = Identity (c (f x))
|
||||
|
||||
|
||||
-- | A generic query with a left-associative binary operator
|
||||
gmapQl :: forall a r r'. Data a => (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> a -> r
|
||||
gmapQl o r f = unwrap <<< gfoldl k z
|
||||
where
|
||||
k :: forall d b. Data d => Const r (d->b) -> d -> Const r b
|
||||
k c x = Const $ (unwrap c) `o` f x
|
||||
z :: forall g. g -> Const r g
|
||||
z _ = Const r
|
||||
|
||||
-- | A generic query with a right-associative binary operator
|
||||
gmapQr :: forall a r r'. Data a => (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> a -> r
|
||||
gmapQr o r0 f x0 = unQr (gfoldl k (const (Qr identity)) x0) r0
|
||||
where
|
||||
k :: forall d b. Data d => Qr r (d->b) -> d -> Qr r b
|
||||
k (Qr c) x = Qr (\r -> c (f x `o` r))
|
||||
|
||||
|
||||
-- | A generic query that processes the immediate subterms and returns a list
|
||||
-- of results. The list is given in the same order as originally specified
|
||||
-- in the declaration of the data constructors.
|
||||
gmapQ :: forall a u. Data a => (forall d. Data d => d -> u) -> a -> Array u
|
||||
gmapQ f = gmapQr (A.cons) [] f
|
||||
|
||||
|
||||
-- | A generic query that processes one child by index (zero-based)
|
||||
gmapQi :: forall u a. Data a => Int -> (forall d. Data d => d -> u) -> a -> u
|
||||
gmapQi i f x = case gfoldl k z x of Qi _ q -> case q of
|
||||
Nothing -> unsafeCoerce "UNEXPECTED NOTHING"
|
||||
Just q' -> q'
|
||||
where
|
||||
k :: forall d b. Data d => Qi u (d -> b) -> d -> Qi u b
|
||||
k (Qi i' q) a = Qi (i'+1) (if i==i' then Just (f a) else q)
|
||||
z :: forall g q. g -> Qi q g
|
||||
z _ = Qi 0 Nothing
|
||||
|
||||
|
||||
-- | A generic monadic transformation that maps over the immediate subterms
|
||||
--
|
||||
-- The default definition instantiates the type constructor @c@ in
|
||||
-- the type of 'gfoldl' to the monad datatype constructor, defining
|
||||
-- injection and projection using 'return' and '>>='.
|
||||
gmapM :: forall m a. Data a => Monad m => (forall d. Data d => d -> m d) -> a -> m a
|
||||
|
||||
-- Use immediately the monad datatype constructor
|
||||
-- to instantiate the type constructor c in the type of gfoldl,
|
||||
-- so injection and projection is done by return and >>=.
|
||||
--
|
||||
gmapM f = gfoldl k pure
|
||||
where
|
||||
k :: forall b d. Data d => m (d -> b) -> d -> m b
|
||||
k c x = do c' <- c
|
||||
x' <- f x
|
||||
pure (c' x')
|
||||
|
||||
|
||||
-- | Transformation of at least one immediate subterm does not fail
|
||||
gmapMp :: forall m a. Data a => MonadPlus m => (forall d. Data d => d -> m d) -> a -> m a
|
||||
|
||||
{-
|
||||
|
||||
The type constructor that we use here simply keeps track of the fact
|
||||
if we already succeeded for an immediate subterm; see Mp below. To
|
||||
this end, we couple the monadic computation with a Boolean.
|
||||
|
||||
-}
|
||||
|
||||
gmapMp f x = unMp (gfoldl k z x) >>= \(Tuple x' b) ->
|
||||
if b then pure x' else empty
|
||||
where
|
||||
z :: forall g. g -> Mp m g
|
||||
z g = Mp (pure (Tuple g false))
|
||||
k :: forall d b. Data d => Mp m (d -> b) -> d -> Mp m b
|
||||
k (Mp c) y
|
||||
= Mp ( c >>= \(Tuple h b) ->
|
||||
(f y >>= \y' -> pure (Tuple (h y') true))
|
||||
<|> pure (Tuple (h y) b)
|
||||
)
|
||||
|
||||
-- | Transformation of one immediate subterm with success
|
||||
gmapMo :: forall m a. Data a => MonadPlus m => (forall d. Data d => d -> m d) -> a -> m a
|
||||
|
||||
{-
|
||||
|
||||
We use the same pairing trick as for gmapMp,
|
||||
i.e., we use an extra Boolean component to keep track of the
|
||||
fact whether an immediate subterm was processed successfully.
|
||||
However, we cut of mapping over subterms once a first subterm
|
||||
was transformed successfully.
|
||||
|
||||
-}
|
||||
|
||||
gmapMo f x = unMp (gfoldl k z x) >>= \(Tuple x' b) ->
|
||||
if b then pure x' else empty
|
||||
where
|
||||
z :: forall g. g -> Mp m g
|
||||
z g = Mp (pure (Tuple g false))
|
||||
k :: forall d b. Data d => Mp m (d -> b) -> d -> Mp m b
|
||||
k (Mp c) y
|
||||
= Mp ( c >>= \(Tuple h b) -> if b
|
||||
then pure (Tuple (h y) b)
|
||||
else (f y >>= \y' -> pure (Tuple (h y') true))
|
||||
<|> pure (Tuple (h y) b)
|
||||
)
|
||||
|
||||
|
||||
|
||||
-- | Type constructor for adding counters to queries
|
||||
data Qi q a = Qi Int (Maybe q)
|
||||
|
||||
|
||||
-- | The type constructor used in definition of gmapQr
|
||||
newtype Qr r a = Qr (r -> r)
|
||||
|
||||
unQr :: forall r a. Qr r a -> r -> r
|
||||
unQr (Qr f) = f
|
||||
|
||||
-- | The type constructor used in definition of gmapMp
|
||||
newtype Mp m x = Mp (m (Tuple x Boolean))
|
||||
|
||||
unMp :: forall m x. Mp m x -> m (Tuple x Boolean)
|
||||
unMp (Mp f) = f
|
||||
|
||||
|
||||
{-
|
||||
gmapT :: forall a. Data a => (forall b. Data b => b -> b) -> a -> a
|
||||
gmapT = let DataDict f _ _ = dataDict in f
|
||||
|
||||
gmapQ :: forall a. Data a => forall r. (forall b. Data b => b -> r) -> a -> Array r
|
||||
gmapQ = let DataDict _ f _ = dataDict in f
|
||||
|
||||
gmapM :: forall a. Data a => (forall m. Monad m => (forall b. Data b => b -> m b) -> a -> m a)
|
||||
gmapM = let DataDict _ _ f = dataDict in f
|
||||
-}
|
||||
|
||||
-- | Left-associative fold operation for constructor applications.
|
||||
--
|
||||
-- The type of 'gfoldl' is a headache, but operationally it is a simple
|
||||
-- generalisation of a list fold.
|
||||
--
|
||||
-- The default definition for 'gfoldl' is @'const' 'id'@, which is
|
||||
-- suitable for abstract datatypes with no substructures.
|
||||
-- gfoldl
|
||||
|
||||
{-
|
||||
|
||||
-- Common instances
|
||||
-- TODO: Why do we need `Tag0` here? Instead of `Typeable`.
|
||||
instance dataArray :: (Tag0 a, Data a) => Data (Array a) where
|
||||
dataDict = DataDict gmapT' gmapQ' gmapM'
|
||||
where
|
||||
gmapT' :: (forall b. Data b => b -> b) -> Array a -> Array a
|
||||
gmapT' f arr = case A.uncons arr of
|
||||
Nothing -> []
|
||||
Just x -> A.cons (f x.head) (f x.tail)
|
||||
gmapQ' :: forall r. (forall b. Data b => b -> r) -> Array a -> Array r
|
||||
gmapQ' f arr = case A.uncons arr of
|
||||
Nothing -> []
|
||||
Just x -> [f x.head, f x.tail]
|
||||
gmapM' :: forall m. (Monad m => (forall b. Data b => b -> m b) -> Array a -> m (Array a))
|
||||
gmapM' f arr = case A.uncons arr of
|
||||
Nothing -> pure []
|
||||
Just x -> do
|
||||
x' <- f x.head
|
||||
xs' <- f x.tail
|
||||
pure (A.cons x' xs')
|
||||
|
||||
instance dataBoolean :: Data Boolean where
|
||||
dataDict = DataDict gmapT' gmapQ' gmapM'
|
||||
where
|
||||
gmapT' :: (forall b. Data b => b -> b) -> Boolean -> Boolean
|
||||
gmapT' f x = x
|
||||
gmapQ' :: forall r. (forall b. Data b => b -> r) -> Boolean -> Array r
|
||||
gmapQ' f x = []
|
||||
gmapM' :: forall m. (Monad m => (forall b. Data b => b -> m b) -> Boolean -> m Boolean)
|
||||
gmapM' f x = pure x
|
||||
|
||||
-}
|
||||
|
||||
-- Combinators
|
||||
|
||||
-- | Apply a transformation everywhere, bottom-up
|
||||
everywhere :: forall a. Data a => (forall b. Data b => b -> b) -> a -> a
|
||||
everywhere f x = f (gmapT (everywhere f) x)
|
||||
|
||||
-- | Apply a transformation everywhere, top-down
|
||||
everywhere' :: forall a. Data a => (forall b. Data b => b -> b) -> a -> a
|
||||
everywhere' f x = gmapT (everywhere' f) (f x)
|
||||
|
||||
-- | Summarise all nodes in top-down, left-to-right
|
||||
everything :: forall a r. Data a => (r -> r -> r) -> (forall b. Data b => b -> r) -> a -> r
|
||||
everything k f x = foldl k (f x) (gmapQ (everything k f) x)
|
||||
|
||||
-- | Apply a monadic transformation everywhere, bottom-up
|
||||
everywhereM :: forall m a. Monad m => Data a => (forall b. Data b => b -> m b) -> a -> m a
|
||||
everywhereM f x = gmapM (everywhereM f) x >>= f
|
||||
Loading…
Reference in New Issue
Block a user