todo.due-label

The short English label shown next to a todo: "2 days overdue", "Due today", "Due tomorrow", "Due Fri 2 Oct".

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

Pinned by 21 tests, run in TypeScript, Python and Rust.

What it does

The short label an app shows next to a todo, worked out from todo.due-status so a todo labelled overdue is also in the Overdue section and counted as overdue in the summary.

| Status | Label | | --- | --- | | done, or no due date | `""` (show nothing) | | overdue | `"1 day overdue"`, `"12 days overdue"` | | today | `"Due today"` | | tomorrow | `"Due tomorrow"` | | this week or later | `"Due Fri 2 Oct"`; `"Due Fri 1 Jan 2027"` when the year differs from today's |

For example

due_label(id a, title Task a, notes —, done true, priority none, due 2026-09-20, tags , recurrence —, created at 2026-09-01T09:00:00Z, completed at 2026-09-27T18:00:00Z, order 0, 2026-09-28) → a done todo shows nothing, even when its date has passed
due_label(id a, title Task a, notes —, done true, priority none, due —, tags , recurrence —, created at 2026-09-01T09:00:00Z, completed at 2026-09-27T18:00:00Z, order 0, 2026-09-28) → a done todo with no date shows nothing
due_label(id a, title Task a, notes —, done false, priority none, due —, tags , recurrence —, created at 2026-09-01T09:00:00Z, completed at —, order 0, 2026-09-28) → no due date shows nothing

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 due_label(todo: Todo, today: str) -> str

todo	Todo
today	date	the user's local date, from the app; never the clock
returns	string	empty for a done todo or one with no due date

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

from fune.todo.due_label import due_label  # todo.due-label@^1

impl/python.py · 27 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 .dates_add_days import parse_iso_date  ← from dates.add-days ^1.0.0 · built alongside by fune
from .dates_day_of_week import day_name  ← from dates.day-of-week ^1.0.0 · built alongside by fune
from .dates_days_between import days_between  ← from dates.days-between ^1.0.0 · built alongside by fune
from .todo_due_status import due_status  ← from todo.due-status ^1.0.0 · built alongside by fune
from .todo_item import Todo  ← from todo.item ^1.0.0 · built alongside by fune

MONTHS = ["Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"]


def due_label(todo: Todo, today: str) -> str:
    """The short English label for a todo's due date, built on due_status."""
    status = due_status(todo, today)
    if status == "done" or status == "none":
        return ""
    due = todo.due
    assert due is not None
    if status == "overdue":
        late = days_between(due, today)
        return "1 day overdue" if late == 1 else "%d days overdue" % late
    if status == "today":
        return "Due today"
    if status == "tomorrow":
        return "Due tomorrow"
    d = parse_iso_date(due)
    label = "Due %s %d %s" % (day_name(due)[0:3], d.day, MONTHS[d.month - 1])
    # The year only when it differs, so next January never reads as this one.
    return label if d.year == parse_iso_date(today).year else "%s %d" % (label, d.year)

Install

fune build

With that line in your source, in a Python project (language python in fune.project), fune build resolves it and its 5 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.due-label

Download for Python todo.due-label-1.0.0-python.fune · 11,338 bytes sha256 0d3e9e1da47899dcd141003047764de86e0a25f635351ffbe37acf40aa5a3acd

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

The whole function, every language, is one file too: todo.due-label-1.0.0.fune, 14,494 bytes, sha256 8aefefe87feab04119b7d82cf60a2bc4f421a0265722e14f34271dd4a0d7e21e. 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.due-label

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

# fune: after todo.due-label

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 dates.add-days in todo.due-label
# fune: replace dates.day-of-week in todo.due-label
# fune: replace dates.days-between in todo.due-label
# fune: replace todo.due-status in todo.due-label
# fune: replace todo.item in todo.due-label

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.due-label --steps.

# fune: step todo.due-label 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 done todo shows nothing, even when its date has passed	id a, title Task a, notes —, done true, priority none, due 2026-09-20, tags , recurrence —, created at 2026-09-01T09:00:00Z, completed at 2026-09-27T18:00:00Z, order 0, 2026-09-28	→
a done todo with no date shows nothing	id a, title Task a, notes —, done true, priority none, due —, tags , recurrence —, created at 2026-09-01T09:00:00Z, completed at 2026-09-27T18:00:00Z, order 0, 2026-09-28	→
no due date shows nothing	id a, title Task a, notes —, done false, priority none, due —, tags , recurrence —, created at 2026-09-01T09:00:00Z, completed at —, order 0, 2026-09-28	→
one day late is singular	id a, title Task a, notes —, done false, priority none, due 2026-09-27, tags , recurrence —, created at 2026-09-01T09:00:00Z, completed at —, order 0, 2026-09-28	→	1 day overdue
ten days late	id a, title Task a, notes —, done false, priority none, due 2026-09-18, tags , recurrence —, created at 2026-09-01T09:00:00Z, completed at —, order 0, 2026-09-28	→	10 days overdue
due last New Year's Eve is 271 days overdue	id a, title Task a, notes —, done false, priority none, due 2025-12-31, tags , recurrence —, created at 2026-09-01T09:00:00Z, completed at —, order 0, 2026-09-28	→	271 days overdue
due today	id a, title Task a, notes —, done false, priority none, due 2026-09-28, tags , recurrence —, created at 2026-09-01T09:00:00Z, completed at —, order 0, 2026-09-28	→	Due today
due tomorrow	id a, title Task a, notes —, done false, priority none, due 2026-09-29, tags , recurrence —, created at 2026-09-01T09:00:00Z, completed at —, order 0, 2026-09-28	→	Due tomorrow
Friday this week, seen on Monday	id a, title Task a, notes —, done false, priority none, due 2026-10-02, tags , recurrence —, created at 2026-09-01T09:00:00Z, completed at —, order 0, 2026-09-28	→	Due Fri 2 Oct
Sunday is still this week	id a, title Task a, notes —, done false, priority none, due 2026-10-04, tags , recurrence —, created at 2026-09-01T09:00:00Z, completed at —, order 0, 2026-09-28	→	Due Sun 4 Oct

Show the other 11 tests

Case	Arguments		Expected
next Monday is later, same format	id a, title Task a, notes —, done false, priority none, due 2026-10-05, tags , recurrence —, created at 2026-09-01T09:00:00Z, completed at —, order 0, 2026-09-28	→	Due Mon 5 Oct
the day has no leading zero	id a, title Task a, notes —, done false, priority none, due 2026-11-09, tags , recurrence —, created at 2026-09-01T09:00:00Z, completed at —, order 0, 2026-09-28	→	Due Mon 9 Nov
a date next year carries the year	id a, title Task a, notes —, done false, priority none, due 2027-01-01, tags , recurrence —, created at 2026-09-01T09:00:00Z, completed at —, order 0, 2026-09-28	→	Due Fri 1 Jan 2027
on Thursday 31 December, Sunday 3 January is this week and carries the year	id a, title Task a, notes —, done false, priority none, due 2027-01-03, tags , recurrence —, created at 2026-09-01T09:00:00Z, completed at —, order 0, 2026-12-31	→	Due Sun 3 Jan 2027
on New Year's Day, New Year's Eve is 1 day overdue	id a, title Task a, notes —, done false, priority none, due 2026-12-31, tags , recurrence —, created at 2026-09-01T09:00:00Z, completed at —, order 0, 2027-01-01	→	1 day overdue
on Saturday, Sunday is tomorrow	id a, title Task a, notes —, done false, priority none, due 2026-10-04, tags , recurrence —, created at 2026-09-01T09:00:00Z, completed at —, order 0, 2026-10-03	→	Due tomorrow
on Saturday, Monday is later	id a, title Task a, notes —, done false, priority none, due 2026-10-05, tags , recurrence —, created at 2026-09-01T09:00:00Z, completed at —, order 0, 2026-10-03	→	Due Mon 5 Oct
today in the wrong format	id a, title Task a, notes —, done false, priority none, due 2026-10-02, tags , recurrence —, created at 2026-09-01T09:00:00Z, completed at —, order 0, 28/09/2026	→	error: is not an ISO date
today with a trailing newline	id a, title Task a, notes —, done false, priority none, due 2026-10-02, tags , recurrence —, created at 2026-09-01T09:00:00Z, completed at —, order 0, 2026-09-28	→	error: is not an ISO date
a due date that never existed	id a, title Task a, notes —, done false, priority none, due 2026-02-30, tags , recurrence —, created at 2026-09-01T09:00:00Z, completed at —, order 0, 2026-09-28	→	error: is not a real calendar date
a bad today is an error even on a done todo	id a, title Task a, notes —, done true, priority none, due —, tags , recurrence —, created at 2026-09-01T09:00:00Z, completed at 2026-09-27T18:00:00Z, order 0, 2026-9-28	→	error: is not an ISO date

More from the author

- **English only.** Three-letter English weekday and month names, the day without a leading zero. A localised app should not translate these strings: map the `DueStatus` from todo.due-status itself and format the date with its own locale data. - The overdue count is whole calendar days (dates.days-between), since due dates have no time of day. There is no "yesterday": one day late is `"1 day overdue"`. - The year is added whenever the due date is in a different calendar year from today, in either direction, so a date next January is never mistaken for this January. - `today` is passed in by the app. Malformed or impossible dates are errors, with dates.add-days's messages, even on a done todo.

Files

Path	Bytes
README.md	1,205
impl/python.py	1,089
impl/rust.rs	1,741
impl/typescript.ts	1,211
vectors.json	6,442