vary 0.1.0.1 → 0.1.0.2

raw patch · 3 files changed

+38/−36 lines, 3 files

Files

• src/Vary.hs +4/−2
• src/Vary/Utils.hs +33/−33
• vary.cabal +1/−1

@@ -72,12 +72,14 @@ -- >>> import qualified Vary -- -- You probably often want to use it together with the "Vary.Either" module:--- >>> import Vary.Either (VEither(VLeft, VRight))+--+-- >>> import Vary.VEither (VEither(VLeft, VRight)) -- >>> import qualified Vary.VEither as VEither --  -- And for many functions, it is useful (and sometimes outright necessary) to enable the following extensions: ----- >>> :set -XGHC2021 -- Of these, Vary uses: TypeApplications, TypeOperators, FlexibleContexts+-- >>> -- Of the GHC2021 set, Vary uses: TypeApplications, TypeOperators, FlexibleContexts:+-- >>> :set -XGHC2021  -- >>> :set -XDataKinds -- -- Finally, some example snippets in this module make use of 'Data.Function.&', the left-to-right function application operator.

@@ -7,22 +7,29 @@ {-# LANGUAGE TypeFamilyDependencies #-} {-# LANGUAGE AllowAmbiguousTypes #-} module Vary.Utils(+    -- | +    -- This module contains functions and typeclasses/type families (type-level functions)+    -- that are not useful in every day usage,+    -- but are sometimes _very_ useful in:+    --+    -- - highly generic code+    -- - When you want to implement typeclasses for 'Vary'.+    -- - When you want to have access to the internals of Vary to debug something   -    -- * Useful in generic code+    -- * Useful in generic code and when implementing typeclasses     (:|), -    KnownPrefix(..), -    Length,      Subset(..), -    Index, -    IndexOf, -    Mappable, +    Mappable,+    Length, +    Index,+    IndexOf,     pop, -    -- * Informational+    -- * Informational (for Debugging)     size,     activeIndex, -    -- * Helper+    -- * Helper functions     natValue,  ) where @@ -67,22 +74,14 @@   -- | Provide evidence that @xs@ is a subset of @es@.+--+-- This is used to make 'Vary.morph' and 'Vary.VEither.morph' work. class (KnownPrefix es) => Subset (xs :: [Type]) (es :: [Type]) where   subsetFullyKnown :: Bool   subsetFullyKnown =     -- Don't show "minimal complete definition" in haddock.     error "subsetFullyKnown" -  -- reifyIndices :: [Int]-  -- reifyIndices =-  --   -- Don't show "minimal complete definition" in haddock.-  --   error "reifyIndices"--  -- reifyIndicesVec :: UVector Int-  -- reifyIndicesVec =-  --   -- Don't show "minimal complete definition" in haddock.-  --   error "reifyIndicesVec"-   morph' :: Vary xs -> Vary ys   morph' =     -- Don't show "minimal complete definition" in haddock.@@ -100,31 +99,21 @@   where   subsetFullyKnown = False --- reifyIndices = []--- {-# INLINE reifyIndicesVec #-}--- reifyIndicesVec = UVector.empty- -- If the subset is fully known, we're done. instance (KnownPrefix es) => Subset '[] es where   subsetFullyKnown = True --- reifyIndices = []--- {-# INLINE reifyIndicesVec #-}--- reifyIndicesVec = UVector.empty -- UVector.empty- instance (e :| es, Subset xs es) => Subset (e : xs) es where   subsetFullyKnown = subsetFullyKnown @xs @es -  -- reifyIndices = natValue @(IndexOf e es) : reifyIndices @xs @es-  -- {-# INLINE reifyIndicesVec #-}-  -- reifyIndicesVec = UVector.fromList (natValue @(IndexOf e es) : reifyIndices @xs @es) -- UVector.cons (natValue @(IndexOf e es)) (reifyIndicesVec @xs @es)-   morph' (Vary 0 a) = Vary (natValue @(IndexOf e es)) a   morph' (Vary n a) = morph' @xs @es (Vary (n - 1) a)  ----  -- | Calculate length of a statically known prefix of @es@.+--+-- Used as part of `Subset`. class KnownPrefix (es :: [Type]) where   prefixLength :: Int @@ -137,13 +126,15 @@ ----  -- | Require that @xs@ is the unknown suffix of @es@.+--+-- Used as part of `Subset`. class (xs :: [k]) `IsUnknownSuffixOf` (es :: [k])  instance {-# INCOHERENT #-} (xs ~ es) => xs `IsUnknownSuffixOf` es  instance (xs `IsUnknownSuffixOf` es) => xs `IsUnknownSuffixOf` (e : es) --- | Get list length+-- | Type-level function to compute the length of a type-level list type family Length (xs :: [k]) :: Nat where   Length xs = Length' 0 xs @@ -151,6 +142,9 @@   Length' n '[] = n   Length' n (x ': xs) = Length' (n + 1) xs +-- | A slight generalization of 'GHC.TypeLits.natVal' to return arbitrary 'Num'.+--+-- (List indexes are never negative, after all.) natValue :: forall (n :: Nat) a. (KnownNat n, Num a) => a {-# INLINEABLE natValue #-} natValue = fromIntegral (natVal (Proxy :: Proxy n))@@ -168,7 +162,9 @@     'Text "Cannot map from " ':<>: 'ShowType a ':<>: 'Text " into " ':<>: 'ShowType b      :$$: 'Text "as it cannot be found in the list " ':<>: 'ShowType l) --- | Get the first index of a type+-- | Look up the index a particular type has in a type-level-list.+--+-- This index is what is used to determine the tag value stored in a 'Vary'.  type IndexOf (x :: k) (xs :: [k]) = IndexOf' (MaybeIndexOf x xs) x xs  -- | Get the first index of a type@@ -192,7 +188,11 @@   MaybeIndexOf' n x (x ': xs) = n + 1   MaybeIndexOf' n x (y ': xs) = MaybeIndexOf' (n + 1) x xs --- | Indexed access into the list+-- | Given a type-level index, look up the type at that index.+--+-- If you ever see the @Type_List_Too_Vague...@ in a type error,+-- it means that you need to make the (prefix) of the list of types more concrete+-- by adding some type annotations somewhere. type Index (n :: Nat) (l :: [k]) = Type_List_Too_Vague___Please_Specify_Prefix_Of_List_Including_The_Desired_Type's_Location n l l  -- | We use this ridiculous name

@@ -5,7 +5,7 @@ -- see: https://github.com/sol/hpack  name:           vary-version:        0.1.0.1+version:        0.1.0.2 synopsis:       Vary: Friendly and fast polymorphic variants (open unions/coproducts/extensible sums) description:    Vary: Friendly and fast Variant types for Haskell                 .