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https://github.com/idris-lang/Idris2.git
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21c6f4fb79
* [ breaking ] remove parsing of dangling binders It used to be the case that ``` ID : Type -> Type ID a = a test : ID (a : Type) -> a -> a test = \ a, x => x ``` and ``` head : List $ a -> Maybe a head [] = Nothing head (x :: _) = Just x ``` were accepted but these are now rejected because: * `ID (a : Type) -> a -> a` is parsed as `(ID (a : Type)) -> a -> a` * `List $ a -> Maybe a` is parsed as `List (a -> Maybe a)` Similarly if you want to use a lambda / rewrite / let expression as part of the last argument of an application, the use of `$` or parens is now mandatory. This should hopefully allow us to make progress on #1703
195 lines
5.7 KiB
Idris
195 lines
5.7 KiB
Idris
module Data.Validated
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import Data.List1
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import Decidable.Equality
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%default total
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||| `Validated` is like an `Either` but accumulates all errors with semigroup operation.
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public export
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data Validated e a = Valid a | Invalid e
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--- Instances of standard interfaces ---
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public export
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(Eq e, Eq a) => Eq (Validated e a) where
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Valid x == Valid y = x == y
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Invalid e == Invalid f = e == f
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_ == _ = False
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export
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(Show e, Show a) => Show (Validated e a) where
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showPrec d $ Valid x = showCon d "Valid" $ showArg x
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showPrec d $ Invalid e = showCon d "Invalid" $ showArg e
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public export
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Functor (Validated e) where
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map f $ Valid x = Valid $ f x
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map _ $ Invalid e = Invalid e
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public export
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Bifunctor Validated where
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bimap _ s $ Valid x = Valid $ s x
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bimap f _ $ Invalid e = Invalid $ f e
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public export
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Bifoldable Validated where
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bifoldr _ g acc (Valid a) = g a acc
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bifoldr f _ acc (Invalid e) = f e acc
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bifoldl _ g acc (Valid a) = g acc a
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bifoldl f _ acc (Invalid e) = f acc e
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binull _ = False
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public export
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Bitraversable Validated where
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bitraverse _ g (Valid a) = Valid <$> g a
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bitraverse f _ (Invalid e) = Invalid <$> f e
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||| Applicative composition preserves invalidity sequentially accumulating all errors.
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public export
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Semigroup e => Applicative (Validated e) where
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pure = Valid
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Valid f <*> Valid x = Valid $ f x
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Invalid e1 <*> Invalid e2 = Invalid $ e1 <+> e2
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Invalid e <*> Valid _ = Invalid e
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Valid _ <*> Invalid e = Invalid e
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-- There is no `Monad` implementation because it can't be coherent with the accumulating `Applicative` one.
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||| Semigroup operation selects the leftmost valid value.
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||| If both sides are invalid, errors are accumulated.
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public export
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Semigroup e => Semigroup (Validated e a) where
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l@(Valid _) <+> _ = l
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_ <+> r@(Valid _) = r
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Invalid e1 <+> Invalid e2 = Invalid $ e1 <+> e2
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public export
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Monoid e => Monoid (Validated e a) where
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neutral = Invalid neutral
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||| Alternative composition preserves validity selecting the leftmost valid value.
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||| If both sides are invalid, errors are accumulated.
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public export
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Monoid e => Alternative (Validated e) where
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empty = neutral
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l@(Valid _) <|> _ = l
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_ <|> r@(Valid _) = r
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Invalid e1 <|> Invalid e2 = Invalid $ e1 <+> e2
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public export
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Foldable (Validated e) where
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foldr op init $ Valid x = x `op` init
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foldr _ init $ Invalid _ = init
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foldl op init $ Valid x = init `op` x
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foldl _ init $ Invalid _ = init
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null $ Valid _ = False
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null $ Invalid _ = True
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public export
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Traversable (Validated e) where
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traverse f $ Valid x = Valid <$> f x
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traverse _ $ Invalid e = pure $ Invalid e
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public export
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Semigroup e => Zippable (Validated e) where
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zipWith f (Valid l) (Valid r) = Valid $ f l r
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zipWith _ (Valid _) (Invalid r) = Invalid r
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zipWith _ (Invalid l) (Valid _) = Invalid l
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zipWith _ (Invalid l) (Invalid r) = Invalid $ l <+> r
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zipWith3 f (Valid x) (Valid y) (Valid z) = Valid $ f x y z
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zipWith3 _ (Valid _) (Valid _) (Invalid z) = Invalid z
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zipWith3 _ (Valid _) (Invalid y) (Valid _) = Invalid y
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zipWith3 _ (Valid _) (Invalid y) (Invalid z) = Invalid $ y <+> z
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zipWith3 _ (Invalid x) (Valid _) (Valid _) = Invalid x
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zipWith3 _ (Invalid x) (Valid _) (Invalid z) = Invalid $ x <+> z
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zipWith3 _ (Invalid x) (Invalid y) (Valid _) = Invalid $ x <+> y
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zipWith3 _ (Invalid x) (Invalid y) (Invalid z) = Invalid $ x <+> y <+> z
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unzipWith f (Valid x) = let (a, b) = f x in (Valid a, Valid b)
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unzipWith _ (Invalid e) = (Invalid e, Invalid e)
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unzipWith3 f (Valid x) = let (a, b, c) = f x in (Valid a, Valid b, Valid c)
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unzipWith3 _ (Invalid e) = (Invalid e, Invalid e, Invalid e)
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public export
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Uninhabited (Valid x = Invalid e) where
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uninhabited Refl impossible
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public export
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Uninhabited (Invalid e = Valid x) where
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uninhabited Refl impossible
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public export
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(DecEq e, DecEq a) => DecEq (Validated e a) where
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decEq (Valid x) (Invalid y) = No uninhabited
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decEq (Invalid x) (Valid y) = No uninhabited
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decEq (Valid x) (Valid y) with (decEq x y)
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decEq (Valid _) (Valid _) | Yes p = rewrite p in Yes Refl
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decEq (Valid _) (Valid _) | No up = No $ \case Refl => up Refl
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decEq (Invalid x) (Invalid y) with (decEq x y)
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decEq (Invalid _) (Invalid _) | Yes p = rewrite p in Yes Refl
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decEq (Invalid _) (Invalid _) | No up = No $ \case Refl => up Refl
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--- Convenience representations ---
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||| Special case of `Validated` with a `List` as an error accumulator.
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public export %inline
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ValidatedL : Type -> Type -> Type
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ValidatedL = Validated . List1
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public export %inline
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oneInvalid : Applicative f => e -> Validated (f e) a
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oneInvalid = Invalid . pure
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--- Conversions to and from `Either` ---
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public export %inline
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fromEither : Either e a -> Validated e a
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fromEither $ Right x = Valid x
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fromEither $ Left e = Invalid e
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public export %inline
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fromEitherL : Either e a -> ValidatedL e a
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fromEitherL $ Right x = Valid x
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fromEitherL $ Left e = oneInvalid e
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public export %inline
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toEither : Validated e a -> Either e a
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toEither $ Valid x = Right x
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toEither $ Invalid e = Left e
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--- Conversions to and from `Maybe` ---
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public export %inline
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fromMaybe : Monoid e => Maybe a -> Validated e a
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fromMaybe $ Just x = Valid x
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fromMaybe $ Nothing = empty
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public export %inline
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toMaybe : Validated e a -> Maybe a
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toMaybe $ Valid x = Just x
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toMaybe $ Invalid _ = Nothing
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--- Property of being valid ---
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public export
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data IsValid : Validated e a -> Type where
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ItIsValid : IsValid $ Valid x
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export
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Uninhabited (IsValid $ Invalid e) where
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uninhabited ItIsValid impossible
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public export
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isItValid : (v : Validated e a) -> Dec (IsValid v)
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isItValid $ Valid _ = Yes ItIsValid
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isItValid $ Invalid _ = No absurd
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