unisonweb/unison

switch `Patch` to use `Map` instead of `Relation`

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#1,658 opened on Aug 17, 2020

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 (0 comments) (0 reactions) (0 assignees)Haskell (6,624 stars) (304 forks)batch import
help wanted

Description

We don't need the reverse index that Relation provides hanging out in memory.

We don't want to risk changing the existing V1 serialization format, so for simplicity, when constructing this PR, convert to/from a Relation using Relation.toMultimap/.fromMultimap before calling the serialization functions.

Contributor guide

Tech stack
None
Domain
backendperformance
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.
half day
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
HaskellUnison internalsPatch type
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
40
Research direction
Investigate the Patch module in the Unison codebase to understand the current use of Relation. Replace Relation with a Map, ensuring the reverse index is not needed. Use Relation.toMultimap and fromMultimap for serialization compatibility. Check that existing serialization tests pass.