jfmengels/elm-review-simplify

Simplify `List.filterMap (\foo -> if x then Just foo else Nothing)` to `List.filter (\foo -> x)`

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#340 opened on Feb 25, 2025

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 (2 comments) (1 reaction) (0 assignees)Elm (10 forks)github user discovery
enhancementhelp wanted

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Description

Example of things the rule would report:

List.filterMap (\foo -> if x then Just foo else Nothing)
--> List.filter (\foo -> x)

Example of things the rule would not report:

List.filterMap (\foo -> if x then Just (foo + 2) else Nothing)

I am looking for:

  • Someone to implement it with/for me

Contributor guide

Research direction
Study existing simplification rules in the repository to understand the pattern matching and reporting structure. Then implement a new rule that detects List.filterMap calls with an if then else returning Just or Nothing and suggests replacing with List.filter.
Tech stack
None
Domain
developer experience
Issue type
Feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
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.
Clear
Prerequisites
Elmelm review
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
75