-- Hoogle documentation, generated by Haddock
-- See Hoogle, http://www.haskell.org/hoogle/
-- | Uncurry functions with multiple arguments.
--
-- This library provides a version of "uncurry" which takes a function of
-- multiple arguments and stores the arguments into an n-ary product from
-- "sop-core". The first non-function type encountered in the signature
-- is considered the "end of the function".
--
-- This library also provides a way of reassociating a sequence of nested
-- Eithers, so that the innermost Rigth value floats to the top-level
-- Right branch.
@package multicurryable
@version 0.1.0.0
-- | While writing function decorators, we often need to store the
-- arguments of the function in a n-ary product. multiuncurry
-- @(<-) is useful for that.
--
-- Less often, when processing the result of functions, we have a nested
-- chain of Eithers like Either Err1 (Either Err2 (Either Err3
-- Success)), and want to put all the errors in a top-level
-- Left branch, and the lone Success value in a top-level
-- Right branch. multiuncurry @Either is useful
-- for that.
--
-- The Multicurryable class will get terribly confused if it can't
-- determine the rightmost type, because it can't be sure it's not
-- another (->), or another Either. So use it only
-- with concrete rightmost types, not polymorphic ones.
module Multicurryable
class Multicurryable (f :: Type -> Type -> Type) (items :: [Type]) a curried | f items a -> curried, f curried -> items a where {
type UncurriedArgs f :: [Type] -> Type;
}
multiuncurry :: Multicurryable f items a curried => curried -> f (UncurriedArgs f items) a
multicurry :: Multicurryable f items a curried => f (UncurriedArgs f items) a -> curried
-- | An n-ary product.
--
-- The product is parameterized by a type constructor f and
-- indexed by a type-level list xs. The length of the list
-- determines the number of elements in the product, and if the
-- i-th element of the list is of type x, then the
-- i-th element of the product is of type f x.
--
-- The constructor names are chosen to resemble the names of the list
-- constructors.
--
-- Two common instantiations of f are the identity functor
-- I and the constant functor K. For I, the product
-- becomes a heterogeneous list, where the type-level list describes the
-- types of its components. For K a, the product becomes
-- a homogeneous list, where the contents of the type-level list are
-- ignored, but its length still specifies the number of elements.
--
-- In the context of the SOP approach to generic programming, an n-ary
-- product describes the structure of the arguments of a single data
-- constructor.
--
-- Examples:
--
--
-- I 'x' :* I True :* Nil :: NP I '[ Char, Bool ]
-- K 0 :* K 1 :* Nil :: NP (K Int) '[ Char, Bool ]
-- Just 'x' :* Nothing :* Nil :: NP Maybe '[ Char, Bool ]
--
data NP (a :: k -> Type) (b :: [k])
[Nil] :: forall {k} (a :: k -> Type). NP a ('[] :: [k])
[:*] :: forall {k} (a :: k -> Type) (x :: k) (xs :: [k]). a x -> NP a xs -> NP a (x : xs)
infixr 5 :*
-- | An n-ary sum.
--
-- The sum is parameterized by a type constructor f and indexed
-- by a type-level list xs. The length of the list determines
-- the number of choices in the sum and if the i-th element of
-- the list is of type x, then the i-th choice of the
-- sum is of type f x.
--
-- The constructor names are chosen to resemble Peano-style natural
-- numbers, i.e., Z is for "zero", and S is for
-- "successor". Chaining S and Z chooses the corresponding
-- component of the sum.
--
-- Examples:
--
--
-- Z :: f x -> NS f (x ': xs)
-- S . Z :: f y -> NS f (x ': y ': xs)
-- S . S . Z :: f z -> NS f (x ': y ': z ': xs)
-- ...
--
--
-- Note that empty sums (indexed by an empty list) have no non-bottom
-- elements.
--
-- Two common instantiations of f are the identity functor
-- I and the constant functor K. For I, the sum
-- becomes a direct generalization of the Either type to
-- arbitrarily many choices. For K a, the result is a
-- homogeneous choice type, where the contents of the type-level list are
-- ignored, but its length specifies the number of options.
--
-- In the context of the SOP approach to generic programming, an n-ary
-- sum describes the top-level structure of a datatype, which is a choice
-- between all of its constructors.
--
-- Examples:
--
--
-- Z (I 'x') :: NS I '[ Char, Bool ]
-- S (Z (I True)) :: NS I '[ Char, Bool ]
-- S (Z (K 1)) :: NS (K Int) '[ Char, Bool ]
--
data NS (a :: k -> Type) (b :: [k])
[Z] :: forall {k} (a :: k -> Type) (x :: k) (xs :: [k]). a x -> NS a (x : xs)
[S] :: forall {k} (a :: k -> Type) (xs :: [k]) (x :: k). NS a xs -> NS a (x : xs)
-- | The identity type functor.
--
-- Like Identity, but with a shorter name.
newtype I a
I :: a -> I a
instance Multicurryable.MulticurryableE (Multicurryable.IsEither curried) items a curried => Multicurryable.Multicurryable Data.Either.Either items a curried
instance Multicurryable.MulticurryableE 'GHC.Types.False '[] a a
instance Multicurryable.MulticurryableE (Multicurryable.IsEither curried) rest tip curried => Multicurryable.MulticurryableE 'GHC.Types.True (i : rest) tip (Data.Either.Either i curried)
instance Multicurryable.MulticurryableF (Multicurryable.IsFunction curried) items a curried => Multicurryable.Multicurryable (->) items a curried
instance Multicurryable.MulticurryableF 'GHC.Types.False '[] a a
instance Multicurryable.MulticurryableF (Multicurryable.IsFunction curried) rest tip curried => Multicurryable.MulticurryableF 'GHC.Types.True (i : rest) tip (i -> curried)