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Diffstat (limited to 'third_party/bazel/rules_haskell/examples/primitive/Data/Primitive.hs')
-rw-r--r-- | third_party/bazel/rules_haskell/examples/primitive/Data/Primitive.hs | 85 |
1 files changed, 85 insertions, 0 deletions
diff --git a/third_party/bazel/rules_haskell/examples/primitive/Data/Primitive.hs b/third_party/bazel/rules_haskell/examples/primitive/Data/Primitive.hs new file mode 100644 index 000000000000..db545ed81514 --- /dev/null +++ b/third_party/bazel/rules_haskell/examples/primitive/Data/Primitive.hs @@ -0,0 +1,85 @@ +{-# LANGUAGE MagicHash #-} +{-# OPTIONS_GHC -fno-warn-duplicate-exports #-} +-- | +-- Module : Data.Primitive +-- Copyright : (c) Roman Leshchinskiy 2009-2012 +-- License : BSD-style +-- +-- Maintainer : Roman Leshchinskiy <rl@cse.unsw.edu.au> +-- Portability : non-portable +-- +-- Reexports all primitive operations +-- +module Data.Primitive ( + -- * Re-exports + module Data.Primitive.Types + ,module Data.Primitive.Array + ,module Data.Primitive.ByteArray + ,module Data.Primitive.Addr + ,module Data.Primitive.SmallArray + ,module Data.Primitive.UnliftedArray + ,module Data.Primitive.PrimArray + ,module Data.Primitive.MutVar + -- * Naming Conventions + -- $namingConventions +) where + +import Data.Primitive.Types +import Data.Primitive.Array +import Data.Primitive.ByteArray +import Data.Primitive.Addr +import Data.Primitive.SmallArray +import Data.Primitive.UnliftedArray +import Data.Primitive.PrimArray +import Data.Primitive.MutVar + +{- $namingConventions +For historical reasons, this library embraces the practice of suffixing +the name of a function with the type it operates on. For example, three +of the variants of the array indexing function are: + +> indexArray :: Array a -> Int -> a +> indexSmallArray :: SmallArray a -> Int -> a +> indexPrimArray :: Prim a => PrimArray a -> Int -> a + +In a few places, where the language sounds more natural, the array type +is instead used as a prefix. For example, @Data.Primitive.SmallArray@ +exports @smallArrayFromList@, which would sound unnatural if it used +@SmallArray@ as a suffix instead. + +This library provides several functions traversing, building, and filtering +arrays. These functions are suffixed with an additional character to +indicate their the nature of their effectfulness: + +* No suffix: A non-effectful pass over the array. +* @-A@ suffix: An effectful pass over the array, where the effect is 'Applicative'. +* @-P@ suffix: An effectful pass over the array, where the effect is 'PrimMonad'. + +Additionally, an apostrophe can be used to indicate strictness in the elements. +The variants with an apostrophe are used in @Data.Primitive.Array@ but not +in @Data.Primitive.PrimArray@ since the array type it provides is always strict in the element. +For example, there are three variants of the function that filters elements +from a primitive array. + +> filterPrimArray :: (Prim a ) => (a -> Bool) -> PrimArray a -> PrimArray a +> filterPrimArrayA :: (Prim a, Applicative f) => (a -> f Bool) -> PrimArray a -> f (PrimArray a) +> filterPrimArrayP :: (Prim a, PrimMonad m) => (a -> m Bool) -> PrimArray a -> m (PrimArray a) + +As long as the effectful context is a monad that is sufficiently affine +the behaviors of the 'Applicative' and 'PrimMonad' variants produce the same results +and differ only in their strictness. Monads that are sufficiently affine +include: + +* 'IO' and 'ST' +* Any combination of 'MaybeT', 'ExceptT', 'StateT' and 'Writer' on top + of another sufficiently affine monad. + +There is one situation where the names deviate from effectful suffix convention +described above. Throughout the haskell ecosystem, the 'Applicative' variant of +'map' is known as 'traverse', not @mapA@. Consequently, we adopt the following +naming convention for mapping: + +> mapPrimArray :: (Prim a, Prim b) => (a -> b) -> PrimArray a -> PrimArray b +> traversePrimArray :: (Applicative f, Prim a, Prim b) => (a -> f b) -> PrimArray a -> f (PrimArray b) +> traversePrimArrayP :: (PrimMonad m, Prim a, Prim b) => (a -> m b) -> PrimArray a -> m (PrimArray b) +-} |