ndmitchell / ndmitchell/hlint

Suggest DeriveAnyClass

Open
#956 12 comments 1 reaction 0 assignees View on GitHub

Nobody has claimed this yet.

Dominant language
Haskell
Stars
1.6k
Forks
210
PR merge metrics
No merged PRs in 30d

Description

We can write

data Foo = { x, y, z :: T }

instance C1 Foo

instance C2 Foo

as just

data Foo = { x, y, z :: T } deriving (C1, C2)

Could HLint suggest this?

Contributor guide

No contributing guide indexed for this repository

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by locating HLint's rules for data declarations and standalone instance declarations, then inspect nearby tests for suggestion patterns. Add coverage for the shown C1 and C2 transformation, including the expected suggested deriving clause; done means HLint reliably suggests the equivalent combined declaration.

Written by the indexing model from the issue text.

Assessment

Tech stack
haskell
Domain
tooling
Issue type
Feature
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

Get new issues in your inbox

A short digest of beginner-friendly GitHub issues.