Unaligned bit arrays on the JavaScript target

Author: richard-viney

.github/workflows/ci.yml

@@ -38,16 +38,23 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
+        gleam_version: ["1.6.0", "nightly"]
         node_version: ["18.20", "20.16", "22.5"]
     steps:
       - uses: actions/checkout@v4
       - uses: erlef/setup-beam@v1
         with:
           otp-version: "27.0"
-          gleam-version: "1.6.0"
+          gleam-version: ${{ matrix.gleam_version }}
+          version-type: strict
       - uses: actions/setup-node@v4
         with:
           node-version: ${{ matrix.node_version }}
+
+      # Disable tests involving unaligned bit arrays when not on nightly
+      - if: matrix.gleam_version != 'nightly'
+        run: rm test/gleam/*_unaligned_test.gleam
+
       - run: gleam test --target javascript --runtime node
 
   test_javascript_bun:
@@ -56,16 +63,23 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
+        gleam_version: ["1.6.0", "nightly"]
         bun_version: ["1.1"]
     steps:
       - uses: actions/checkout@v4
       - uses: erlef/setup-beam@v1
         with:
           otp-version: "27.0"
-          gleam-version: "1.6.0"
+          gleam-version: ${{ matrix.gleam_version }}
+          version-type: strict
       - uses: oven-sh/setup-bun@v2
         with:
           bun-version: ${{ matrix.bun_version }}
+
+      # Disable tests involving unaligned bit arrays when not on nightly
+      - if: matrix.gleam_version != 'nightly'
+        run: rm test/gleam/*_unaligned_test.gleam
+
       - run: gleam test --target javascript --runtime bun
 
   test_javascript_deno:
@@ -74,14 +88,21 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
+        gleam_version: ["1.6.0", "nightly"]
         deno_version: ["1.45"]
     steps:
       - uses: actions/checkout@v4
       - uses: erlef/setup-beam@v1
         with:
           otp-version: "27.0"
-          gleam-version: "1.6.0"
+          gleam-version: ${{ matrix.gleam_version }}
+          version-type: strict
       - uses: denoland/setup-deno@v1
         with:
           deno-version: ${{ matrix.deno_version }}
+
+      # Disable tests involving unaligned bit arrays when not on nightly
+      - if: matrix.gleam_version != 'nightly'
+        run: rm test/gleam/*_unaligned_test.gleam
+
       - run: gleam test --target javascript --runtime deno

CHANGELOG.md

@@ -2,12 +2,12 @@
 
 ## Unreleased
 
-- The performance of `dict.is_empty` has been improved.
-
-## v0.54.0 - 2025-02-04
-
 - The `uri` module gains the `empty` value, representing an empty URI which
   equivalent to `""`.
+- The performance of `dict.is_empty` has been improved.
+- Unaligned bit arrays on the JavaScript target are now supported by the
+  functions in the `bit_array` module. Note: Gleam >= v1.9 is required to use
+  unaligned bit arrays on the JavaScript target.
 
 ## v0.54.0 - 2025-02-04
 

src/gleam/bit_array.gleam

@@ -13,22 +13,20 @@ pub fn from_string(x: String) -> BitArray
 /// Returns an integer which is the number of bits in the bit array.
 ///
 @external(erlang, "erlang", "bit_size")
-pub fn bit_size(x: BitArray) -> Int {
-  byte_size(x) * 8
-}
+@external(javascript, "../gleam_stdlib.mjs", "bit_array_bit_size")
+pub fn bit_size(x: BitArray) -> Int
 
 /// Returns an integer which is the number of bytes in the bit array.
 ///
 @external(erlang, "erlang", "byte_size")
-@external(javascript, "../gleam_stdlib.mjs", "length")
+@external(javascript, "../gleam_stdlib.mjs", "bit_array_byte_size")
 pub fn byte_size(x: BitArray) -> Int
 
 /// Pads a bit array with zeros so that it is a whole number of bytes.
 ///
 @external(erlang, "gleam_stdlib", "bit_array_pad_to_bytes")
-pub fn pad_to_bytes(x: BitArray) -> BitArray {
-  x
-}
+@external(javascript, "../gleam_stdlib.mjs", "bit_array_pad_to_bytes")
+pub fn pad_to_bytes(x: BitArray) -> BitArray
 
 /// Creates a new bit array by joining two bit arrays.
 ///