gleam-lang/gleam

Use memory arena for types when type checking

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#2,250 opened on Jun 29, 2023

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help wanted

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Description

Currently, we represent types using a nested tree structure in which nodes are reference counted. This is at times awkward to work with, not particularly well-suited to a multithreaded compilation, and potentially slower than using an arena due to the overhead of reference, counting and memory fragmentation. Use an id based memory arena instead.

It is only during type interference and checking that we need to mutate types and to have the various different kinds of type variables, so for all other parts of the compiler, we can have a different, simpler data structure with which to represent types. Related to https://github.com/gleam-lang/gleam/issues/865

Contributor guide

Research direction
Study the current type representation in Gleam's compiler, understand the arena pattern, and design an id based arena for types. Inspect the related issue and codebase for type inference.
Tech stack
rust
Domain
compilers
Issue type
Refactor
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
4
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.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Mostly clear
Prerequisites
Rustcompiler design
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
20