todo.tag-counts

How many todos carry each tag, for a tag sidebar: most used first, open todos only unless asked.

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

Pinned by 10 tests, run in TypeScript, Python and Rust.

What it does

How many todos carry each tag, for a tag sidebar or filter chips: a list of `{ tag, count }`, most used first, ties in tag order (code point, via collections.sort-by, so `b-2`, `b10`, `b2`, not natural-number order).

- With `includeDone` false only open todos count, so the sidebar shows what is left to do; a tag whose todos are all done is left out rather than listed with a zero. - A todo counts once per tag, even if its tag list repeats one. - Tags are counted as stored. todo.item keeps them normalised (todo.normalise-tags), so `home` and `#Home` are already one tag.

For example

tag_counts(todos ×6, false) → ×3 open todos only: ties go alphabetically
tag_counts(todos ×6, true) → ×4 including done todos adds bills and more home and work
tag_counts(, true) → an empty list has no tags

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.

def tag_counts(todos: Sequence[Todo], include_done: bool) -> List[TagCount]

todos	Todo[]
include_done	bool	false counts only open todos
returns	TagCount[]	count descending, then tag ascending; no zero counts

The type it declares, generated into your project

@dataclass(frozen=True)
class TagCount:
    """One tag and how many todos carry it."""

    tag: str
    count: int

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

from fune.todo.tag_counts import tag_counts  # todo.tag-counts@^1

impl/python.py · 18 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.

from typing import Any, Dict, List, Sequence

from .collections_sort_by import sort_by  ← from collections.sort-by ^1.0.0 · built alongside by fune
from .todo_item import Todo  ← from todo.item ^1.0.0 · built alongside by fune
from .todo_tag_counts_types import TagCount


def tag_counts(todos: Sequence[Todo], include_done: bool) -> List[TagCount]:
    """How many todos carry each tag: most used first, then tag in code-point order."""
    counts: Dict[str, int] = {}
    for todo in todos:
        if todo.done and not include_done:
            continue
        for tag in dict.fromkeys(todo.tags):
            counts[tag] = counts.get(tag, 0) + 1
    rows: List[Dict[str, Any]] = [{"tag": tag, "count": count} for tag, count in counts.items()]
    ordered = sort_by(sort_by(rows, "tag", "asc"), "count", "desc")
    return [TagCount(tag=r["tag"], count=r["count"]) for r in ordered]

Install

fune build

With that line in your source, in a Python project (language python in fune.project), fune build resolves it and its 2 dependencies, pins them in fune.lock, downloads only the Python 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.tag-counts

Download for Python todo.tag-counts-1.0.0-python.fune · 10,405 bytes sha256 89f1e133dacedca52f800b44e10ac642c3718d530470db0cdcb3a11316edfdd2

The manifest, vectors and README with only the Python implementation. Install it without the registry with fune add ./todo.tag-counts-1.0.0-python.fune, or fetch it from a terminal with fune pull todo.tag-counts@1.0.0:python.

The whole function, every language, is one file too: todo.tag-counts-1.0.0.fune, 13,164 bytes, sha256 3666265c41bbbb558c4084744eea9703df9e92cb87e8831c6fd0e5f1d8e56185. 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.tag-counts

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

# fune: after todo.tag-counts

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 collections.sort-by in todo.tag-counts
# fune: replace todo.item in todo.tag-counts

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.tag-counts --steps.

# fune: step todo.tag-counts 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
open todos only: ties go alphabetically	todos ×6, false	→	×3
including done todos adds bills and more home and work	todos ×6, true	→	×4
an empty list has no tags	, true	→
tags only on done todos are left out, not counted as zero	todos ×2, false	→
todos without tags	todos ×2, true	→
a tag repeated on one todo counts once	todos ×1, true	→	×1
ties are code-point order, not natural order: b-2, b10, b2	todos ×1, false	→	×4
count beats alphabet	todos ×3, false	→	×2
one todo's tags come out alphabetically, not in its own order	todos ×1, false	→	×2
a done todo counts when asked	todos ×1, true	→	×1

Files

Path	Bytes
README.md	601
impl/python.py	775
impl/rust.rs	1,632
impl/typescript.ts	1,000
vectors.json	6,278