haskell/haskell-ide-engine

Hlint parser error on `pattern`

Open

#1,374 opened on Aug 28, 2019

View on GitHub
 (2 comments) (0 reactions) (0 assignees)Haskell (205 forks)batch import
component: hlintgardening 🌱good first issue

Repository metrics

Stars
 (2,358 stars)
PR merge metrics
 (No merged PRs in 30d)

Description

Given a module:

module Lib where

foo pattern = pattern

This error message is shown:

/tmp/ghc-mod4106/Lib4105-43.hs:3:5: error:
    parse error on input `pattern'
  module Lib where
  
> foo pattern = pattern

This is documented in https://github.com/ndmitchell/hlint/issues/607. Minimal project to reproduce: https://github.com/fendor/hlint-minimal-pattern

This happens because hlint assumes some default extensions. This makes sense, since hlint is normally not aware of a .cabal or package.yaml file, where extensions may be listed. However, HIE is aware of language extensions and could invoke hlint always with the right extensions.

Contributor guide

Research direction
Study how HIE configures and calls hlint, then modify the invocation to include language extensions from the project's configuration (cabal or hie.yaml).
Tech stack
None
Domain
developer experience
Issue type
Bug
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
HaskellGit
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
65