todo.normalise-tags

Clean up tags as typed: trim, drop the #, lower-case slug form, drop empties and duplicates, keep the order.

1.0.0 · published 2026-10-03 by charlie · Anterra

Pinned by 13 tests, run in TypeScript, Python and Rust.

What it does

Turns tags as a person typed them into the one form a todo stores, so that `#Home`, `home` and ` HOME ` are the same tag and a filter on one finds all three.

Each tag loses its leading `#` characters and becomes a slug with text.slugify: lower-case ASCII letters and digits, runs of anything else collapsed to a single hyphen, never a hyphen at either end. So "Home Office" is `home-office`, "Café" is `cafe` and "Straße" is `strasse`. The transliteration covers Latin-1 letters only (see text.slugify): a tag written in another script, or made only of punctuation, comes out empty and is dropped rather than stored as an empty tag.

For example

normaliseTags(Home) → home a capital letter is lower-cased
normaliseTags(#home, HOME, home ) → home #home, HOME and a padded home are one tag
normaliseTags(Home Office) → home-office spaces inside become one hyphen

The function

The same function in TypeScript, Python and Rust, pinned by the same tests. Pick your language; the choice follows you around the registry.

export function normaliseTags(tags: readonly string[]): readonly string[]

tags	string[]	as typed, e.g. ["#Home", " home office ", "HOME"]
returns	string[]	e.g. ["home", "home-office"], first appearance first

Your code names it in one line, in the file that uses it

import { normaliseTags } from "#fune/todo.normalise-tags@^1";

impl/typescript.ts · 17 lines · open · raw

Imports name this capability’s declared dependencies, which fune builds next to it in your project; each one links to its page.

import { slugify } from "./text_slugify.ts";  ← from text.slugify ^1.0.0 · built alongside by fune

/**
 * Tags as a person types them, in the one form every todo stores and
 * compares: "#Home", "home" and " HOME " are one tag. Each tag is stripped of
 * its leading #s and turned into a slug (text.slugify), so "Home Office" is
 * "home-office" and "Café" is "cafe". Tags that come out empty are dropped;
 * repeats keep their first position.
 */
export function normaliseTags(tags: readonly string[]): readonly string[] {
  const out: string[] = [];
  for (const tag of tags) {
    const slug = slugify(tag.replace(/^[ \t\n\r\v\f#]+/, ""));
    if (slug !== "" && !out.includes(slug)) out.push(slug);
  }
  return out;
}

Install

fune build

With that line in your source, in a TypeScript project (language typescript in fune.project), fune build resolves it and its 1 dependency, pins them in fune.lock, downloads only the TypeScript package of each, and builds the code above into your project’s .fune/build, one readable file per capability with a header linking back here. Or pin a range in fune.project and build in one step:

fune add todo.normalise-tags

Download for TypeScript todo.normalise-tags-1.0.0-typescript.fune · 4,667 bytes sha256 599a85e803e7fd4aabcbc4ad6ed7d6f0cfd4ff974405c6fbac3aa8ff18a73d55

The manifest, vectors and README with only the TypeScript implementation. Install it without the registry with fune add ./todo.normalise-tags-1.0.0-typescript.fune, or fetch it from a terminal with fune pull todo.normalise-tags@1.0.0:typescript.

The whole function, every language, is one file too: todo.normalise-tags-1.0.0.fune, 6,037 bytes, sha256 c098ae9cc4cff3719a9100ca369754dcc598f716578252f1b23114de7be44139. It installs into a project of any language.

Customise it in your app

The seams this capability offers. Put a marker directly above a function of your own and fune build wires it into the built code; the package on the registry is not changed, the built file’s header lists it under CUSTOMISED, and fune hooks lists every hook in the project. How hooks work.

before — your function gets the arguments and returns them, changed or not, or throws to refuse the call.

// fune: before todo.normalise-tags

after — your function gets the result and the arguments, and returns the final result.

// fune: after todo.normalise-tags

replace — inside this capability’s code only, calls to a dependency go to your function, with the same signature. Other capabilities that use it are unaffected; write in * to replace it everywhere.

// fune: replace text.slugify in todo.normalise-tags

step — your function runs at a numbered point inside the function’s body, receives the in-scope values it names as parameters, and may return replacements. List the points with fune show todo.normalise-tags --steps.

// fune: step todo.normalise-tags after <n|label>

Tests

A version published now needs at least 8 tests for every function, and one that expects the error for each function that throws; the registry refuses it otherwise. fune verify --all runs each case in TypeScript, Python and Rust, and a project runs them again with fune verify. This page lists the cases; it does not run them. The exact JSON is vectors.json.

Case	Arguments		Expected
a capital letter is lower-cased	Home	→	home
#home, HOME and a padded home are one tag	#home, HOME, home	→	home
spaces inside become one hyphen	Home Office	→	home-office
accented Latin letters lose their accent	Café	→	cafe
sharp s becomes ss	Straße	→	strasse
several leading #s go	##urgent	→	urgent
tags that come out empty are dropped	#, , !!!,	→
no tags		→
the first appearance keeps its place	work, Errands, #WORK, errands	→	work, errands
digits are kept and punctuation becomes a hyphen	Q3 2026 plan, a_b, c++	→	q3-2026-plan, a-b, c

Show the other 3 tests

Case	Arguments		Expected
a tag in a script slugify does not transliterate is dropped	日本, home	→	home
an emoji tag is dropped, one beside a word leaves the word	🏠, 🏠 home	→	home
already normal tags are unchanged	home, bills-2026	→	home, bills-2026

More from the author

Repeats are removed after normalising, keeping the first appearance, and the order is otherwise the order typed.

It does not enforce the limits (10 tags, 30 characters each): cutting a tag short or dropping the eleventh silently would lose what was typed. todo.item's validators report those, so the form can say so.

Files

Path	Bytes
README.md	978
impl/python.py	549
impl/rust.rs	748
impl/typescript.ts	671
vectors.json	1,370