From df7ae0de142f520d47a252d56926bd042406be8a Mon Sep 17 00:00:00 2001
From: James Brock <jamesbrock@gmail.com>
Date: Mon, 28 Nov 2022 11:16:47 +0900
Subject: [PATCH 1/2] Upgrade packages.dhall

---
 packages.dhall   | 3 ++-
 spago-test.dhall | 1 -
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/packages.dhall b/packages.dhall
index 582d6d3..2ffa9a7 100644
--- a/packages.dhall
+++ b/packages.dhall
@@ -1,4 +1,5 @@
 let upstream =
-      https://raw.githubusercontent.com/purescript/package-sets/prepare-0.15/src/packages.dhall
+      https://github.com/purescript/package-sets/releases/download/psc-0.15.4-20221102/packages.dhall
+        sha256:8628e413718876ce26983db1d0ce9d9e1588129117fa3bb8ed9f618db6914127
 
 in  upstream
diff --git a/spago-test.dhall b/spago-test.dhall
index ab1a012..7037d90 100644
--- a/spago-test.dhall
+++ b/spago-test.dhall
@@ -5,7 +5,6 @@ in conf // {
   , "foldable-traversable"
   , "partial"
   , "refs"
-  , "typelevel-prelude"
   , "tuples"
   , "quickcheck"
   , "quickcheck-laws"

From 94e031e31c980bb5f456d04fd544b15ff05225fa Mon Sep 17 00:00:00 2001
From: James Brock <jamesbrock@gmail.com>
Date: Mon, 28 Nov 2022 12:20:33 +0900
Subject: [PATCH 2/2] New module: Data.ArrayBuffer.Cast

---
 CHANGELOG.md                           |  2 ++
 src/Data/ArrayBuffer/Cast.purs         | 46 ++++++++++++++++++++++++++
 src/Data/ArrayBuffer/ValueMapping.purs |  7 ++--
 3 files changed, 53 insertions(+), 2 deletions(-)
 create mode 100644 src/Data/ArrayBuffer/Cast.purs

diff --git a/CHANGELOG.md b/CHANGELOG.md
index ad44db1..7d83901 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,8 @@ Breaking changes:
 
 New features:
 
+- `Data.ArrayBuffer.Cast` (#46 by @jamesdbrock)
+
 Bugfixes:
 
 Other improvements:
diff --git a/src/Data/ArrayBuffer/Cast.purs b/src/Data/ArrayBuffer/Cast.purs
new file mode 100644
index 0000000..10e5b0a
--- /dev/null
+++ b/src/Data/ArrayBuffer/Cast.purs
@@ -0,0 +1,46 @@
+-- | `DataView` represents unaligned memory of unknown endianness.
+-- |
+-- | `ArrayView` represents arrays of aligned elements of
+-- | local-machine endianness.
+-- | For the cases of `Int8Array`, `Uint8Array`, `Uint8ClampedArray`,
+-- | the elements
+-- | are single bytes, so they are always aligned and they have no
+-- | endianness. Therefore in those cases we can freely cast back and forth
+-- | to `DataView`.
+module Data.ArrayBuffer.Cast
+  ( fromInt8Array
+  , fromUint8Array
+  , fromUint8ClampedArray
+  , toInt8Array
+  , toUint8Array
+  , toUint8ClampedArray
+  ) where
+
+import Data.ArrayBuffer.DataView as DV
+import Data.ArrayBuffer.Typed as AT
+import Data.ArrayBuffer.Types (DataView, Uint8Array, Uint8ClampedArray, Int8Array)
+import Effect (Effect)
+
+-- | Cast an `Int8Array` to a `DataView`.
+fromInt8Array :: Int8Array -> Effect DataView
+fromInt8Array x = DV.part (AT.buffer x) (AT.byteOffset x) (AT.byteLength x)
+
+-- | Cast a `DataView` to an `Int8Array`.
+toInt8Array :: DataView -> Effect Int8Array
+toInt8Array x = AT.part (DV.buffer x) (DV.byteOffset x) (DV.byteLength x)
+
+-- | Cast a `UInt8Array` to a `DataView`.
+fromUint8Array :: Uint8Array -> Effect DataView
+fromUint8Array x = DV.part (AT.buffer x) (AT.byteOffset x) (AT.byteLength x)
+
+-- | Cast a `DataView` to a `Uint8Array`.
+toUint8Array :: DataView -> Effect Uint8Array
+toUint8Array x = AT.part (DV.buffer x) (DV.byteOffset x) (DV.byteLength x)
+
+-- | Cast a `UInt8ClampedArray` to a `DataView`.
+fromUint8ClampedArray :: Uint8ClampedArray -> Effect DataView
+fromUint8ClampedArray x = DV.part (AT.buffer x) (AT.byteOffset x) (AT.byteLength x)
+
+-- | Cast a `DataView` to a `Uint8ClampedArray`.
+toUint8ClampedArray :: DataView -> Effect Uint8ClampedArray
+toUint8ClampedArray x = AT.part (DV.buffer x) (DV.byteOffset x) (DV.byteLength x)
diff --git a/src/Data/ArrayBuffer/ValueMapping.purs b/src/Data/ArrayBuffer/ValueMapping.purs
index 70ac4f7..8694a19 100644
--- a/src/Data/ArrayBuffer/ValueMapping.purs
+++ b/src/Data/ArrayBuffer/ValueMapping.purs
@@ -12,7 +12,8 @@ import Data.Float32 (Float32) as F
 import Data.UInt (UInt)
 import Type.Proxy (Proxy)
 
--- | Map of each `ArrayViewType` to the number of bytes of storage it requires.
+-- | Type-level map of each `ArrayViewType` to the number of bytes of storage
+-- | it requires.
 class BytesPerType (a :: ArrayViewType) where
   byteWidth :: (Proxy a) -> Int
 
@@ -43,7 +44,8 @@ instance bytesPerTypeFloat32 :: BytesPerType Float32 where
 instance bytesPerTypeFloat64 :: BytesPerType Float64 where
   byteWidth _ = 8
 
--- | Maps a `TypedArray`’s binary casted value to its computable representation in JavaScript.
+-- | Type-level map of `TypedArray`’s binary casted value to its
+-- | representation in JavaScript.
 class BinaryValue (a :: ArrayViewType) (t :: Type) | a -> t
 
 instance binaryValueUint8Clamped :: BinaryValue Uint8Clamped UInt
@@ -56,6 +58,7 @@ instance binaryValueInt8 :: BinaryValue Int8 Int
 instance binaryValueFloat32 :: BinaryValue Float32 F.Float32
 instance binaryValueFloat64 :: BinaryValue Float64 Number
 
+-- | Type-level map of `TypedArray` to its element type name.
 class ShowArrayViewType (a :: ArrayViewType) (name :: Symbol) | a -> name
 
 instance showArrayViewTypeUint8Clamped :: ShowArrayViewType Uint8Clamped "Uint8Clamped"