Sort dependencies alphabetically and put them on separate lines in toml

[nelsyeung]

Problem description

Can we sort dependencies alphabetically and put them in separate lines in the pixi.toml or pyproject.toml when we perform actions that manipulates the toml file? Package managers like uv and npm do this. This is done so that if people remove and add a package back in it won't create a diff or the diff is more meaningful.

For example, right now we run pixi add -f dev --pypi ruff mypy, it'll generate:

[dependency-groups]
dev = ["ruff>=0.15.5,<0.16",   "mypy>=1.19.1,<2"]

If we run pixi remove -f dev --pypi ruff && pixi add -f dev --pypi ruff, the toml becomes:

dev = ["mypy>=1.19.1,<2", "ruff>=0.15.5,<0.16"]

Now the diff exists even though technically nothing has been done.

Usually, people like to do this when they want to force the version to be pinned to a newer version in the toml; if it's sorted and placed on a new line then the diff is more obvious, e.g.,

dev = [
  "mypy>=1.19.1,<2",
-  "ruff>=0.14.14,<0.15",
+  "ruff>=0.15.5,<0.16",
]

[Hofer-Julian]

Could you please elaborate on the behavior of uv and npm? What do they do when the dependencies are not already sorted? Do they then sort all of them?

[nelsyeung]

uv pyproject.toml

Sorry, I didn't realise I partially lied about uv. Here's the exact behaviour.

TLDR; if it's alphabetically ordered in the toml already, whenever we run uv add, it stays ordered. Otherwise, appends the new dependencies alphabetically. It'll always put each dependency on their own line.

Details

Ordering behaviour

Given no dependencies (i.e., dependencies = []), when we run uv add ruff mypy, we get:

dependencies = [
    "mypy>=1.19.1",
    "ruff>=0.14.10",
]

Even though I put ruff before mypy in the uv add command, we still get alphabetical sorting.

When we run uv add pytest, it's still sorted alphabetically:

dependencies = [
    "mypy>=1.19.1",
    "pytest>=9.0.2",
    "ruff>=0.14.10",
]

However, if we manually make it not ordered:

dependencies = [
    "pytest>=9.0.2",
    "mypy>=1.19.1",
    "ruff>=0.14.10",
]

When we run uv add numpy, it's appended to the bottom:

dependencies = [
    "pytest>=9.0.2",
    "mypy>=1.19.1",
    "ruff>=0.14.10",
    "numpy>=2.2.6",
]

Inline behaviour

Given inline dependencies (dependencies = ["mypy>=1.19.1", "ruff>=0.14.10"]), when we run uv add pytest, we get separate lines:

dependencies = [
    "mypy>=1.19.1",
    "pytest>=9.0.2",
    "ruff>=0.14.10",
]

Given unordered inline dependencies (dependencies = ["pytest>=9.0.2", "mypy>=1.19.1", "ruff>=0.14.10"]), when we run uv add numpy, we get unordered but separate lines:

dependencies = [
    "pytest>=9.0.2",
    "mypy>=1.19.1",
    "ruff>=0.14.10",
    "numpy>=2.2.6",
]

npm package.json

TLDR; it's always ordered and separate lines.

Details

Ordering behaviour

Given no dependencies "dependencies": {}, when we run npm i trim-repeated camelcase, we get

  "dependencies": {
    "camelcase": "^9.0.0",
    "trim-repeated": "^2.0.0"
  }

Even though I put camelcase before trim-repeated in the npm i command, we still get alphabetical sorting.

When we run npm i react, it's still sorted alphabetically:

  "dependencies": {
    "camelcase": "^9.0.0",
    "react": "^19.2.4",
    "trim-repeated": "^2.0.0"
  }

Even if we manually make it not ordered:

  "dependencies": {
    "react": "^19.2.4",
    "camelcase": "^9.0.0",
    "trim-repeated": "^2.0.0"
  }

When we run npm i humanize-string, we still get alphabetical sorting:

  "dependencies": {
    "camelcase": "^9.0.0",
    "humanize-string": "^3.1.0",
    "react": "^19.2.4",
    "trim-repeated": "^2.0.0"
  }

Inline behaviour

Given inline ordered/unordered dependencies (e.g., "dependencies": { "trim-repeated": "^2.0.0", "camelcase": "^9.0.0" }), when we run npm i react, we get ordered and separate lines:

  "dependencies": {
    "camelcase": "^9.0.0",
    "react": "^19.2.4",
    "trim-repeated": "^2.0.0"
  }

[Hofer-Julian]

The uv behavior sounds good to me.

[ruben-arts]

As @Hofer-Julian said, the uv style with sorting when already sorted sound like a plan. Contributions are welcome for this.