haskell-nix/hnix

Get string coercions right

Open

#245 opened on Apr 28, 2018

View on GitHub
 (2 comments) (0 reactions) (1 assignee)Nix (116 forks)github user discovery
easy with C++ knowledgegood first issuehelp wanted

Repository metrics

Stars
 (835 stars)
PR merge metrics
 (No merged PRs in 30d)

Description

According to @shlevy , there are 2 axes of string coercion:

  • coerceToString + coerceMore: Do I coerce integers? Do I recurse into lists?
  • addToStore: If coercing a path, do I just convert it into a string, or add it to the store?

There are several string coercion contexts:

  • toString: coerceMore = true, addToStore = false
  • ${: coerceMore = false, addToStore = true
  • derivation argument: coerceMore = true, addToStore = true
  • implicit coercion: coerceMore = false, addToStore = false
  • forceString: it simply must be a string and nothing else

Shea will double check this.

According to these criteria, we are getting this wrong on toString right now.

Contributor guide

Research direction
Examine the current `toString` implementation and ensure it uses `coerceMore` = true and `addToStore` = false as described. Trace the coercion path to identify where it deviates.
Tech stack
haskell
Domain
compilers
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.
Active
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