avh4/elm-format

formatting is slow (~1 minute) for large (~5000 elements) lists

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#753 opened on Dec 6, 2021

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 (2 comments) (1 reaction) (0 assignees)Haskell (1,329 stars) (148 forks)batch import
help wantedperformanceupgraded-parser

Description

While greatly improved by https://github.com/avh4/elm-format/issues/642, something is still slow for large lists. Two Elm Slack users have noted that files with ~5000 element literal lists can take more than a minute to format.

Contributor guide

Tech stack
None
Domain
performancetooling
Issue type
performance
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-2 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
basic Haskell knowledgefamiliarity with elm format codebase
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
45
Research direction
The issue describes slow formatting for large lists (~5000 elements). Previous improvements were made in PR #642, so start by examining the current formatting algorithm for list literals in the elm format source code. Look for any quadratic or O(n^2) operations related to list handling. Profile the formatting process to identify bottlenecks. Consider optimizing data structures or algorithms to reduce time complexity. The main file likely involves the formatting logic for expressions or lists.