ocaml/dune

dune fmt should be able to format single files

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#7,287 opened on Mar 11, 2023

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 (7 comments) (2 reactions) (1 assignee)OCaml (478 forks)github user discovery
good first issue

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Description

We should expand the capabilities of dune fmt so that it can format files passed on the command line. This would probably involve making a more serious implementation for it rather than just being a command line alias for dune build @fmt --auto-promote.

We have two cases for dune fmt file1.

  • If a file can be formatted, then we should format it according to whatever rule @fmt uses.
  • If it cannot be formatted then either we error or do nothing.

Perhaps we can control the behaviour of the second with an option which will allow users to hook up commit scripts like those proposed in https://github.com/ocaml/dune/issues/5107.

It would also pave the way for requesting a file to be formatted, which we can use to implement more sophisticated features like having the latest files changed in version control only be formatted. Again suggested in https://github.com/ocaml/dune/issues/5107.

I will need to do some more thinking about the implementation so making this ticket in the mean time.

Contributor guide

Research direction
Examine the current implementation of `dune fmt` in the source code, understand how it currently aliases to `dune build @fmt`, and design a way to accept file arguments and format individual files. Look at how other build tools handle similar functionality, and consider the behaviour for unformattable files.
Tech stack
None
Domain
build system
Issue type
Feature
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.
3-5 days
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
OCamlDune
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60