gleam-lang/gleam

Tracking issue for bit arrays on javascript target

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#3,842 opened on Nov 17, 2024

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 (3 comments) (3 reactions) (0 assignees)Rust (21,417 stars) (960 forks)batch import
help wanted

Description

There are still many features of bit arrays that are not yet implemented on the javascript target. We want to have all of them eventually, but it's a lot to implement in one go, and a lot to have a separate issue for each one. So I've decided to create a tracking issue to list them all, and these can be slowly ticked off when people implement specific features.

  • Non byte-aligned access
  • Non-constant sizes when pattern matching: <<bits:size(some_variable)>>
  • Non byte-aligned segments
  • Non-utf8 strings: utf16, utf32, utf16_codepoint and utf32_codepoint
  • Pattern matching on utf8_codepoint, utf16_codepoint and utf32_codepoint
  • Signedness: signed and unsigned
  • Endianness: Missing native
  • Unit specification: unit
  • 16-bit floats

Please let me know if I've missed any. I'm not super familiar with bit array syntax so I mostly just looked through the compiler and found where an error was thrown on javascript.

Contributor guide

Tech stack
javascriptrust
Domain
backend
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
5
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
over 1 week
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
mostly clear
Prerequisites
Gleam knowledgeRust programmingJavaScript target conceptsCompiler internals
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
15
Research direction
Examine the Gleam compiler's JavaScript target code (likely in src/compile/js or similar) to understand how bit arrays are currently handled. The issue lists missing features such as pattern matching on utf8 codepoint, utf16 codepoint, utf32 codepoint, and native endianness. Focus on implementing these features by following existing patterns for other features like signedness and unit specification. The original author suggests reviewing error prone areas for missing implementations.