{
  "id": "property",
  "title": "Property and lettings",
  "summary": "Lettings and property: rent proration and reviews, deposit caps, service charges, yields, stamp duty, council tax, mortgage affordability and completion statements.",
  "synonyms": [
    "property",
    "lettings",
    "letting agent",
    "landlord",
    "tenancy",
    "rent",
    "rental",
    "estate agent",
    "property management",
    "block management",
    "conveyancing",
    "real estate",
    "buy to let",
    "stamp duty"
  ],
  "apps": [
    "letting agent software",
    "landlord app",
    "property management system",
    "rent collection app",
    "block management software",
    "conveyancing case management",
    "property investment calculator",
    "real estate app"
  ],
  "language": "python",
  "includes": [
    "money-basics",
    "dates-basics",
    "validation-basics"
  ],
  "includedBy": [],
  "caveats": [
    "Not legal or tax advice. Stamp duty, deposit caps and council tax follow UK nations' rules on a date; check with a solicitor or tax adviser before relying on them."
  ],
  "sections": [
    {
      "key": "tenancies",
      "title": "Tenancies and rent",
      "purpose": "Set up tenancies and charge rent correctly.",
      "from": "property",
      "members": [
        {
          "id": "property.rent-proration",
          "tier": "core",
          "why": "Rent for part of a month by the annual-daily or calendar-month method, for move-in and move-out.",
          "section": "tenancies",
          "from": "property",
          "version": "1.0.1",
          "summary": "Rent for part of a month from the monthly rent, by the annual-daily or the calendar-month method.",
          "status": "unreviewed",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "prorateRent"
          ],
          "signatures": [
            "def prorate_rent(monthly_rent: Money, from_date: str, to_date: str, method: RentProrationMethod) -> Money"
          ],
          "reference": "from fune.property.rent_proration import prorate_rent  # property.rent-proration@^1",
          "url": "http://www.functionalweave.com/functions/property.rent-proration"
        },
        {
          "id": "property.deposit-cap",
          "tier": "core",
          "why": "The maximum tenancy deposit (five or six weeks' rent) under the Tenant Fees Act 2019.",
          "section": "tenancies",
          "from": "property",
          "version": "1.0.2",
          "summary": "Maximum tenancy deposit a landlord may take: five or six weeks' rent under the Tenant Fees Act 2019.",
          "status": "unreviewed",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "depositCap"
          ],
          "signatures": [
            "def deposit_cap(rent: Money, rent_period: RentPeriod, jurisdiction: str, on_date: str) -> DepositCap"
          ],
          "reference": "from fune.property.deposit_cap import deposit_cap  # property.deposit-cap@^1",
          "url": "http://www.functionalweave.com/functions/property.deposit-cap"
        },
        {
          "id": "property.holding-deposit-cap",
          "tier": "core",
          "why": "The maximum holding deposit to reserve a property: one week's rent.",
          "section": "tenancies",
          "from": "property",
          "version": "1.0.1",
          "summary": "Maximum holding deposit to reserve a rental property: one week's rent (annual rent ÷ 52), rounded down.",
          "status": "unreviewed",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "holdingDepositCap"
          ],
          "signatures": [
            "def holding_deposit_cap(rent: Money, rent_period: RentPeriod) -> Money"
          ],
          "reference": "from fune.property.holding_deposit_cap import holding_deposit_cap  # property.holding-deposit-cap@^1",
          "url": "http://www.functionalweave.com/functions/property.holding-deposit-cap"
        },
        {
          "id": "property.rent-review",
          "tier": "optional",
          "why": "New rent after an index-linked review with collar, cap and upward-only option.",
          "section": "tenancies",
          "from": "property",
          "version": "1.0.1",
          "summary": "New rent after an index-linked (CPI/RPI) rent review, with an optional collar and cap and upward-only option.",
          "status": "unreviewed",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "rentReview"
          ],
          "signatures": [
            "def rent_review(passing_rent: Money, base_index: int, review_index: int, collar_basis_points: Optional[int], cap_basis_points: Optional[int], upward_only: bool) -> RentReviewResult"
          ],
          "reference": "from fune.property.rent_review import rent_review  # property.rent-review@^1",
          "url": "http://www.functionalweave.com/functions/property.rent-review"
        },
        {
          "id": "dates.recurrence",
          "tier": "optional",
          "why": "Monthly rent due dates, month-end safe.",
          "section": "tenancies",
          "from": "property",
          "version": "1.0.0",
          "summary": "The next n dates of a repeating rule: monthly on a day, last weekday of the month, every k days or weeks, yearly.",
          "status": "stable",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "recurrence"
          ],
          "signatures": [
            "def recurrence(rule: RecurrenceRule, start_iso: str, count: int) -> List[str]"
          ],
          "reference": "from fune.dates.recurrence import recurrence  # dates.recurrence@^1",
          "url": "http://www.functionalweave.com/functions/dates.recurrence"
        }
      ],
      "gaps": [
        {
          "key": "deposit-protection",
          "text": "Registering deposits with a protection scheme (DPS, TDS, mydeposits) is done through their services.",
          "section": "tenancies",
          "from": "property"
        },
        {
          "key": "right-to-rent",
          "text": "Right to Rent immigration checks are a Home Office process caps does not have.",
          "section": "tenancies",
          "from": "property"
        }
      ]
    },
    {
      "key": "blocks",
      "title": "Service charges and blocks",
      "purpose": "Share a building's costs between its units.",
      "from": "property",
      "members": [
        {
          "id": "property.service-charge-apportion",
          "tier": "core",
          "why": "Apportions a service charge across units by lease fraction, floor area or percentage, exact to the penny.",
          "section": "blocks",
          "from": "property",
          "version": "1.0.1",
          "summary": "Apportion a service charge across units by lease fraction, floor area or fixed percentage, exact to the penny.",
          "status": "unreviewed",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "apportionServiceCharge"
          ],
          "signatures": [
            "def apportion_service_charge(total: Money, units: Sequence[ServiceChargeUnit], basis: ApportionBasis) -> List[ServiceChargeLine]"
          ],
          "reference": "from fune.property.service_charge_apportion import apportion_service_charge  # property.service-charge-apportion@^1",
          "url": "http://www.functionalweave.com/functions/property.service-charge-apportion"
        },
        {
          "id": "property.floor-area",
          "tier": "optional",
          "why": "Floor area from room dimensions in square metres and square feet.",
          "section": "blocks",
          "from": "property",
          "version": "1.0.2",
          "summary": "Floor area from room lengths and widths, exactly, with the total in both square metres and square feet.",
          "status": "unreviewed",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "floorArea"
          ],
          "signatures": [
            "def floor_area(rooms: Sequence[RoomDimensions], length_unit: FloorAreaUnit, decimals: int) -> FloorArea"
          ],
          "reference": "from fune.property.floor_area import floor_area  # property.floor-area@^1",
          "url": "http://www.functionalweave.com/functions/property.floor-area"
        },
        {
          "id": "property.council-tax-band",
          "tier": "optional",
          "why": "Council tax for a band from the authority's Band D charge, England, Wales and Scotland.",
          "section": "blocks",
          "from": "property",
          "version": "1.0.2",
          "summary": "Council tax for a valuation band from the Band D charge: the statutory band ratio, England, Wales and Scotland.",
          "status": "unreviewed",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "councilTaxBand"
          ],
          "signatures": [
            "def council_tax_band(band_d_charge: Money, band: str, nation: str, on_date: str) -> CouncilTaxBandCharge"
          ],
          "reference": "from fune.property.council_tax_band import council_tax_band  # property.council-tax-band@^1",
          "url": "http://www.functionalweave.com/functions/property.council-tax-band"
        }
      ],
      "gaps": []
    },
    {
      "key": "buying",
      "title": "Buying and conveyancing",
      "purpose": "Work out what a purchase costs and what changes hands on completion.",
      "from": "property",
      "members": [
        {
          "id": "property.stamp-duty",
          "tier": "core",
          "why": "SDLT, LBTT or LTT on a purchase, with first-time buyer relief and surcharges.",
          "section": "buying",
          "from": "property",
          "version": "1.0.2",
          "summary": "Stamp duty on a property purchase: SDLT (England, NI), LBTT (Scotland), LTT (Wales), with reliefs and surcharges.",
          "status": "unreviewed",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "stampDuty"
          ],
          "signatures": [
            "def stamp_duty(purchase: StampDutyPurchase) -> StampDutyResult"
          ],
          "reference": "from fune.property.stamp_duty import stamp_duty  # property.stamp-duty@^1",
          "url": "http://www.functionalweave.com/functions/property.stamp-duty"
        },
        {
          "id": "property.completion-statement",
          "tier": "core",
          "why": "A buyer's completion statement: price less deposit, apportioned ground rent and service charge, fees.",
          "section": "buying",
          "from": "property",
          "version": "1.0.1",
          "summary": "A buyer's completion statement: price less deposit, ground rent and service charge apportioned to completion, plus fees.",
          "status": "unreviewed",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "completionStatement"
          ],
          "signatures": [
            "def completion_statement(price: Money, deposit_paid: Money, completion_date: str, apportionments: Sequence[PeriodCharge], fees: Sequence[FeeLine]) -> CompletionStatement"
          ],
          "reference": "from fune.property.completion_statement import completion_statement  # property.completion-statement@^1",
          "url": "http://www.functionalweave.com/functions/property.completion-statement"
        },
        {
          "id": "property.mortgage-affordability",
          "tier": "optional",
          "why": "Mortgage income multiple and stress-tested repayment against income.",
          "section": "buying",
          "from": "property",
          "version": "1.0.1",
          "summary": "Mortgage affordability: the loan-to-income multiple and a stress-tested repayment against income, both checked.",
          "status": "unreviewed",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "mortgageAffordability"
          ],
          "signatures": [
            "def mortgage_affordability(annual_income: Money, monthly_commitments: Money, loan: Money, annual_rate_basis_points: int, stress_rate_basis_points: int, term_months: int, max_income_multiple_basis_points: int, max_debt_to_income_basis_points: int) -> MortgageAffordability"
          ],
          "reference": "from fune.property.mortgage_affordability import mortgage_affordability  # property.mortgage-affordability@^1",
          "url": "http://www.functionalweave.com/functions/property.mortgage-affordability"
        },
        {
          "id": "lending.loan-payment",
          "tier": "optional",
          "why": "Monthly mortgage payment for a principal, rate and term.",
          "section": "buying",
          "from": "property",
          "version": "1.0.1",
          "summary": "Level repayment for a loan (annuity formula), computed exactly and rounded once, the way you choose.",
          "status": "unreviewed",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "loanPayment"
          ],
          "signatures": [
            "def loan_payment(principal: Money, annual_rate_basis_points: int, term_months: int, payments_per_year: int, mode: RoundingMode) -> Money"
          ],
          "reference": "from fune.lending.loan_payment import loan_payment  # lending.loan-payment@^1",
          "url": "http://www.functionalweave.com/functions/lending.loan-payment"
        },
        {
          "id": "lending.ltv",
          "tier": "optional",
          "why": "Loan-to-value and its band, for mortgage quotes.",
          "section": "buying",
          "from": "property",
          "version": "1.0.1",
          "summary": "Loan-to-value ratio in basis points, and the band it falls in from a band table you supply.",
          "status": "unreviewed",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "loanToValue"
          ],
          "signatures": [
            "def loan_to_value(loan: Money, property_value: Money, bands: Sequence[LtvBand]) -> LtvResult"
          ],
          "reference": "from fune.lending.ltv import loan_to_value  # lending.ltv@^1",
          "url": "http://www.functionalweave.com/functions/lending.ltv"
        }
      ],
      "gaps": []
    },
    {
      "key": "investment",
      "title": "Investment returns",
      "purpose": "Judge a property as an investment.",
      "from": "property",
      "members": [
        {
          "id": "property.rental-yield",
          "tier": "optional",
          "why": "Gross and net rental yield from annual rent, costs and value.",
          "section": "investment",
          "from": "property",
          "version": "1.0.1",
          "summary": "Gross and net rental yield of a let property, in basis points, from annual rent, costs and value.",
          "status": "unreviewed",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "rentalYield"
          ],
          "signatures": [
            "def rental_yield(annual_rent: Money, annual_costs: Money, property_value: Money) -> RentalYield"
          ],
          "reference": "from fune.property.rental_yield import rental_yield  # property.rental-yield@^1",
          "url": "http://www.functionalweave.com/functions/property.rental-yield"
        }
      ],
      "gaps": []
    },
    {
      "key": "amounts",
      "title": "Amounts",
      "purpose": "Hold money as currency-tagged integer minor units and do plain arithmetic on it safely.",
      "from": "money-basics",
      "members": [
        {
          "id": "money.amount",
          "tier": "core",
          "why": "The Money type ({ minor, currency }) every other money capability takes and returns.",
          "section": "amounts",
          "from": "money-basics",
          "version": "1.0.2",
          "summary": "A currency-tagged monetary amount held in integer minor units.",
          "status": "stable",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "money"
          ],
          "signatures": [
            "def money(minor: int, currency: str) -> Money"
          ],
          "reference": "from fune.money.amount import money  # money.amount@^1",
          "url": "http://www.functionalweave.com/functions/money.amount"
        },
        {
          "id": "money.add",
          "tier": "core",
          "why": "Adds and subtracts amounts, refusing to mix currencies by accident.",
          "section": "amounts",
          "from": "money-basics",
          "version": "1.0.1",
          "summary": "Add, subtract and negate monetary amounts, refusing to mix currencies.",
          "status": "stable",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "addMoney"
          ],
          "signatures": [
            "def add_money(a: Money, b: Money) -> Money"
          ],
          "reference": "from fune.money.add import add_money  # money.add@^1",
          "url": "http://www.functionalweave.com/functions/money.add"
        },
        {
          "id": "money.sum",
          "tier": "core",
          "why": "Totals a list of amounts, with an explicit currency for an empty list.",
          "section": "amounts",
          "from": "money-basics",
          "version": "1.0.1",
          "summary": "Total a list of monetary amounts, with an explicit currency for the empty case.",
          "status": "stable",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "sumMoney"
          ],
          "signatures": [
            "def sum_money(amounts: Sequence[Money], currency: str) -> Money"
          ],
          "reference": "from fune.money.sum import sum_money  # money.sum@^1",
          "url": "http://www.functionalweave.com/functions/money.sum"
        },
        {
          "id": "money.compare",
          "tier": "core",
          "why": "Compares, mins, maxes and clamps amounts of one currency without unwrapping them.",
          "section": "amounts",
          "from": "money-basics",
          "version": "2.0.0",
          "summary": "Compare two amounts of one currency, refusing to compare across currencies; min, max and clamp too.",
          "status": "stable",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": true,
          "functions": [
            "compareMoney",
            "minMoney",
            "maxMoney",
            "clampMoney"
          ],
          "signatures": [
            "def compare_money(a: Money, b: Money) -> int",
            "def min_money(a: Money, b: Money) -> Money",
            "def max_money(a: Money, b: Money) -> Money",
            "def clamp_money(amount: Money, min: Money, max: Money) -> Money"
          ],
          "reference": "from fune.money.compare import compare_money, min_money, max_money, clamp_money  # money.compare@^2",
          "url": "http://www.functionalweave.com/functions/money.compare"
        }
      ],
      "gaps": []
    },
    {
      "key": "rates",
      "title": "Rates and rounding",
      "purpose": "Apply percentages and divide amounts with the rounding stated, never a float.",
      "from": "money-basics",
      "members": [
        {
          "id": "money.apply-rate",
          "tier": "core",
          "why": "Applies a basis-point rate (VAT, discount, commission) to an amount with explicit rounding.",
          "section": "rates",
          "from": "money-basics",
          "version": "1.0.1",
          "summary": "Apply a rate expressed in basis points to a monetary amount, with an explicit rounding mode.",
          "status": "stable",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "applyRate"
          ],
          "signatures": [
            "def apply_rate(amount: Money, basis_points: int, mode: RoundingMode) -> Money"
          ],
          "reference": "from fune.money.apply_rate import apply_rate  # money.apply-rate@^1",
          "url": "http://www.functionalweave.com/functions/money.apply-rate"
        },
        {
          "id": "math.round-div",
          "tier": "core",
          "why": "Integer division with a named rounding mode, for any money maths the others do not cover.",
          "section": "rates",
          "from": "money-basics",
          "version": "1.0.0",
          "summary": "Integer division with an explicit rounding mode, for money arithmetic that must not drift.",
          "status": "stable",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "roundDiv"
          ],
          "signatures": [
            "def round_div(numerator: int, denominator: int, mode: RoundingMode) -> int"
          ],
          "reference": "from fune.math.round_div import round_div  # math.round-div@^1",
          "url": "http://www.functionalweave.com/functions/math.round-div"
        },
        {
          "id": "math.basis-points",
          "tier": "optional",
          "why": "Converts \"12.5%\" to and from basis points exactly, for rates typed in by users.",
          "section": "rates",
          "from": "money-basics",
          "version": "2.0.0",
          "summary": "Convert a rate between percent, basis points and a plain ratio exactly, as decimal text or integer basis points.",
          "status": "stable",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": true,
          "functions": [
            "convertRate",
            "toBasisPoints",
            "fromBasisPoints"
          ],
          "signatures": [
            "def convert_rate(value: str, from_unit: RateUnit, to_unit: RateUnit) -> str",
            "def to_basis_points(value: str, unit: RateUnit) -> int",
            "def from_basis_points(basis_points: int, unit: RateUnit) -> str"
          ],
          "reference": "from fune.math.basis_points import convert_rate, to_basis_points, from_basis_points  # math.basis-points@^2",
          "url": "http://www.functionalweave.com/functions/math.basis-points"
        },
        {
          "id": "math.percent-change",
          "tier": "optional",
          "why": "Percentage change between two figures in basis points, for \"up 4.2% on last month\".",
          "section": "rates",
          "from": "money-basics",
          "version": "1.0.0",
          "summary": "Percentage change from one value to another, in basis points, with an explicit rounding mode.",
          "status": "stable",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "percentChange"
          ],
          "signatures": [
            "def percent_change(from_value: int, to_value: int, mode: RoundingMode) -> Optional[int]"
          ],
          "reference": "from fune.math.percent_change import percent_change  # math.percent-change@^1",
          "url": "http://www.functionalweave.com/functions/math.percent-change"
        },
        {
          "id": "math.rational",
          "tier": "optional",
          "why": "Exact fractions for rates that must not drift across many steps.",
          "section": "rates",
          "from": "money-basics",
          "version": "2.0.0",
          "summary": "Exact fraction arithmetic, always reduced, for rates and ratios that must not drift.",
          "status": "stable",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": true,
          "functions": [
            "calculateRational",
            "rational",
            "addRational",
            "subtractRational",
            "multiplyRational",
            "divideRational",
            "compareRational",
            "rationalToInteger"
          ],
          "signatures": [
            "def calculate_rational(a: Rational, op: RationalOp, b: Rational) -> Rational",
            "def rational(numerator: int, denominator: int) -> Rational",
            "def add_rational(a: Rational, b: Rational) -> Rational",
            "def subtract_rational(a: Rational, b: Rational) -> Rational",
            "def multiply_rational(a: Rational, b: Rational) -> Rational",
            "def divide_rational(a: Rational, b: Rational) -> Rational",
            "def compare_rational(a: Rational, b: Rational) -> int",
            "def rational_to_integer(r: Rational, mode: RoundingMode) -> int"
          ],
          "reference": "from fune.math.rational import calculate_rational, rational, add_rational, subtract_rational, multiply_rational, divide_rational, compare_rational, rational_to_integer  # math.rational@^2",
          "url": "http://www.functionalweave.com/functions/math.rational"
        },
        {
          "id": "math.round-div-big",
          "tier": "optional",
          "why": "Rounded division on numbers past 2^53, for very large totals.",
          "section": "rates",
          "from": "money-basics",
          "version": "1.0.0",
          "summary": "Divide two integers of any size with an explicit rounding mode, on decimal strings, for exact money sums past 2^53.",
          "status": "stable",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "roundDivBig"
          ],
          "signatures": [
            "def round_div_big(numerator: str, denominator: str, mode: RoundingMode) -> str"
          ],
          "reference": "from fune.math.round_div_big import round_div_big  # math.round-div-big@^1",
          "url": "http://www.functionalweave.com/functions/math.round-div-big"
        }
      ],
      "gaps": []
    },
    {
      "key": "splitting",
      "title": "Splitting",
      "purpose": "Divide an amount between people, periods or lines so the parts add back to the whole.",
      "from": "money-basics",
      "members": [
        {
          "id": "money.allocate",
          "tier": "core",
          "why": "Splits an amount by ratios (60/40, by quantity) without losing or inventing a penny.",
          "section": "splitting",
          "from": "money-basics",
          "version": "1.0.1",
          "summary": "Split an amount across ratios without losing or inventing a single minor unit.",
          "status": "stable",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "allocate"
          ],
          "signatures": [
            "def allocate(amount: Money, ratios: Sequence[int]) -> List[Money]"
          ],
          "reference": "from fune.money.allocate import allocate  # money.allocate@^1",
          "url": "http://www.functionalweave.com/functions/money.allocate"
        },
        {
          "id": "money.split-even",
          "tier": "optional",
          "why": "Splits an amount into n near-equal parts that sum exactly, for instalments or shares.",
          "section": "splitting",
          "from": "money-basics",
          "version": "1.0.0",
          "summary": "Split an amount into n near-equal parts that add back up to exactly the whole.",
          "status": "stable",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "splitEven"
          ],
          "signatures": [
            "def split_even(amount: Money, parts: int) -> List[Money]"
          ],
          "reference": "from fune.money.split_even import split_even  # money.split-even@^1",
          "url": "http://www.functionalweave.com/functions/money.split-even"
        }
      ],
      "gaps": []
    },
    {
      "key": "display",
      "title": "Display and input",
      "purpose": "Show amounts to people and read what they type.",
      "from": "money-basics",
      "members": [
        {
          "id": "money.format",
          "tier": "core",
          "why": "Renders an amount as text with the currency's real number of decimal places.",
          "section": "display",
          "from": "money-basics",
          "version": "1.0.0",
          "summary": "Render a monetary amount as text, using the currency's real minor-unit precision.",
          "status": "stable",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "formatMoney"
          ],
          "signatures": [
            "def format_money(amount: Money) -> str"
          ],
          "reference": "from fune.money.format import format_money  # money.format@^1",
          "url": "http://www.functionalweave.com/functions/money.format"
        },
        {
          "id": "money.parse",
          "tier": "optional",
          "why": "Reads \"£1,234.50\" or \"1.234,50 €\" typed by a user into minor units, strictly.",
          "section": "display",
          "from": "money-basics",
          "version": "1.0.0",
          "summary": "Parse \"£1,234.50\" or \"1.234,50 €\" into integer minor units, strictly: no guessing, no rounding.",
          "status": "stable",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "parseMoney"
          ],
          "signatures": [
            "def parse_money(text: str, currency: str, style: NumberStyle) -> Money"
          ],
          "reference": "from fune.money.parse import parse_money  # money.parse@^1",
          "url": "http://www.functionalweave.com/functions/money.parse"
        },
        {
          "id": "money.currency-digits",
          "tier": "optional",
          "why": "How many decimal places each ISO 4217 currency has, for input boxes and validation.",
          "section": "display",
          "from": "money-basics",
          "version": "1.0.0",
          "summary": "How many decimal places a currency's minor unit has, from the ISO 4217 list.",
          "status": "stable",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "currencyDigits"
          ],
          "signatures": [
            "def currency_digits(currency: str) -> int"
          ],
          "reference": "from fune.money.currency_digits import currency_digits  # money.currency-digits@^1",
          "url": "http://www.functionalweave.com/functions/money.currency-digits"
        }
      ],
      "gaps": []
    },
    {
      "key": "currencies",
      "title": "Other currencies",
      "purpose": "Convert between currencies at a rate you hold.",
      "from": "money-basics",
      "members": [
        {
          "id": "money.convert",
          "tier": "optional",
          "why": "Converts an amount at a supplied exact rate with explicit rounding.",
          "section": "currencies",
          "from": "money-basics",
          "version": "1.0.0",
          "summary": "Convert an amount to another currency at a supplied exact rate, with an explicit rounding mode.",
          "status": "stable",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "convertMoney"
          ],
          "signatures": [
            "def convert_money(amount: Money, rate: ExchangeRate, mode: RoundingMode) -> Money"
          ],
          "reference": "from fune.money.convert import convert_money  # money.convert@^1",
          "url": "http://www.functionalweave.com/functions/money.convert"
        }
      ],
      "gaps": []
    },
    {
      "key": "date-arithmetic",
      "title": "Calendar arithmetic",
      "purpose": "Move and measure ISO dates exactly, with no date library and no clock reads.",
      "from": "dates-basics",
      "members": [
        {
          "id": "dates.add-days",
          "tier": "core",
          "why": "Shifts a date by whole days, for due dates and windows.",
          "section": "date-arithmetic",
          "from": "dates-basics",
          "version": "1.0.0",
          "summary": "Shift an ISO date by a whole number of days, forwards or backwards, with exact calendar arithmetic.",
          "status": "stable",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "addDays"
          ],
          "signatures": [
            "def add_days(iso: str, days: int) -> str"
          ],
          "reference": "from fune.dates.add_days import add_days  # dates.add-days@^1",
          "url": "http://www.functionalweave.com/functions/dates.add-days"
        },
        {
          "id": "dates.add-months",
          "tier": "core",
          "why": "Adds months clamping to month end, so 31 January plus a month is the end of February.",
          "section": "date-arithmetic",
          "from": "dates-basics",
          "version": "1.0.0",
          "summary": "Add calendar months to an ISO date, clamping to the month end: 31 Jan + 1 month is 28 or 29 Feb.",
          "status": "stable",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "addMonths"
          ],
          "signatures": [
            "def add_months(iso: str, months: int) -> str"
          ],
          "reference": "from fune.dates.add_months import add_months  # dates.add-months@^1",
          "url": "http://www.functionalweave.com/functions/dates.add-months"
        },
        {
          "id": "dates.days-between",
          "tier": "core",
          "why": "Signed calendar days between two dates, for ages of invoices and stays.",
          "section": "date-arithmetic",
          "from": "dates-basics",
          "version": "1.0.0",
          "summary": "Calendar days from one ISO date to another, signed: negative when the second date is earlier.",
          "status": "stable",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "daysBetween"
          ],
          "signatures": [
            "def days_between(start_iso: str, end_iso: str) -> int"
          ],
          "reference": "from fune.dates.days_between import days_between  # dates.days-between@^1",
          "url": "http://www.functionalweave.com/functions/dates.days-between"
        },
        {
          "id": "dates.month-boundaries",
          "tier": "core",
          "why": "First and last day of a date's month, for monthly periods and statements.",
          "section": "date-arithmetic",
          "from": "dates-basics",
          "version": "1.0.0",
          "summary": "The first day, last day and length of the calendar month containing a date.",
          "status": "stable",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "monthBoundaries"
          ],
          "signatures": [
            "def month_boundaries(iso: str) -> MonthBoundaries"
          ],
          "reference": "from fune.dates.month_boundaries import month_boundaries  # dates.month-boundaries@^1",
          "url": "http://www.functionalweave.com/functions/dates.month-boundaries"
        },
        {
          "id": "dates.day-of-week",
          "tier": "core",
          "why": "ISO weekday of a date, for weekend rules and opening hours.",
          "section": "date-arithmetic",
          "from": "dates-basics",
          "version": "1.0.0",
          "summary": "The ISO 8601 day of the week for a date: 1 is Monday through 7 is Sunday.",
          "status": "stable",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "dayOfWeek"
          ],
          "signatures": [
            "def day_of_week(iso: str) -> int"
          ],
          "reference": "from fune.dates.day_of_week import day_of_week  # dates.day-of-week@^1",
          "url": "http://www.functionalweave.com/functions/dates.day-of-week"
        },
        {
          "id": "dates.is-leap-year",
          "tier": "optional",
          "why": "Whether a year is a leap year, for 365/366-day calculations.",
          "section": "date-arithmetic",
          "from": "dates-basics",
          "version": "1.0.0",
          "summary": "Whether a year is a Gregorian leap year: every 4th, except centuries, except every 400th.",
          "status": "stable",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "isLeapYear"
          ],
          "signatures": [
            "def is_leap_year(year: int) -> bool"
          ],
          "reference": "from fune.dates.is_leap_year import is_leap_year  # dates.is-leap-year@^1",
          "url": "http://www.functionalweave.com/functions/dates.is-leap-year"
        },
        {
          "id": "dates.overlap",
          "tier": "optional",
          "why": "Days two date ranges share, for prorating and clash checks.",
          "section": "date-arithmetic",
          "from": "dates-basics",
          "version": "1.0.0",
          "summary": "Days two date ranges have in common, with the end of each range stated as inclusive or exclusive.",
          "status": "stable",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "overlapDays"
          ],
          "signatures": [
            "def overlap_days(a_start: str, a_end: str, b_start: str, b_end: str, end_inclusive: bool) -> int"
          ],
          "reference": "from fune.dates.overlap import overlap_days  # dates.overlap@^1",
          "url": "http://www.functionalweave.com/functions/dates.overlap"
        },
        {
          "id": "dates.age",
          "tier": "optional",
          "why": "Age in whole years on a date, handling 29 February birthdays.",
          "section": "date-arithmetic",
          "from": "dates-basics",
          "version": "1.0.0",
          "summary": "Age in whole years on a given date, with 29 February birthdays ageing on 1 March in other years.",
          "status": "stable",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "age"
          ],
          "signatures": [
            "def age(birth_date: str, on_date: str) -> int"
          ],
          "reference": "from fune.dates.age import age  # dates.age@^1",
          "url": "http://www.functionalweave.com/functions/dates.age"
        }
      ],
      "gaps": []
    },
    {
      "key": "reporting-periods",
      "title": "Periods and reporting dates",
      "purpose": "Put dates into the periods reports are grouped by.",
      "from": "dates-basics",
      "members": [
        {
          "id": "dates.quarter",
          "tier": "core",
          "why": "Calendar and fiscal quarter of a date for any year-start month.",
          "section": "reporting-periods",
          "from": "dates-basics",
          "version": "1.0.0",
          "summary": "Calendar quarter and fiscal quarter of a date, with the fiscal year and quarter date ranges, for any start month.",
          "status": "stable",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "quarter"
          ],
          "signatures": [
            "def quarter(iso: str, fiscal_year_start_month: int) -> Quarter"
          ],
          "reference": "from fune.dates.quarter import quarter  # dates.quarter@^1",
          "url": "http://www.functionalweave.com/functions/dates.quarter"
        },
        {
          "id": "dates.week-number",
          "tier": "optional",
          "why": "ISO week number and week-year, for weekly reports.",
          "section": "reporting-periods",
          "from": "dates-basics",
          "version": "1.0.0",
          "summary": "ISO 8601 week number and week-numbering year of a date: weeks start Monday, week 1 holds the first Thursday.",
          "status": "stable",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "weekNumber"
          ],
          "signatures": [
            "def week_number(iso: str) -> IsoWeek"
          ],
          "reference": "from fune.dates.week_number import week_number  # dates.week-number@^1",
          "url": "http://www.functionalweave.com/functions/dates.week-number"
        },
        {
          "id": "dates.day-count-fraction",
          "tier": "optional",
          "why": "Year fraction by ACT/365F, ACT/360, 30/360 or ACT/ACT, for interest periods.",
          "section": "reporting-periods",
          "from": "dates-basics",
          "version": "1.0.0",
          "summary": "Year fraction between two dates by ACT/365F, ACT/360, 30/360, 30E/360 or ACT/ACT ISDA, as an exact fraction.",
          "status": "stable",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "dayCountFraction"
          ],
          "signatures": [
            "def day_count_fraction(start_iso: str, end_iso: str, convention: DayCountConvention) -> YearFraction"
          ],
          "reference": "from fune.dates.day_count_fraction import day_count_fraction  # dates.day-count-fraction@^1",
          "url": "http://www.functionalweave.com/functions/dates.day-count-fraction"
        }
      ],
      "gaps": []
    },
    {
      "key": "working-days",
      "title": "Working days and holidays",
      "purpose": "Skip weekends and public holidays when counting or adding days.",
      "from": "dates-basics",
      "members": [
        {
          "id": "dates.bank-holidays",
          "tier": "core",
          "why": "UK bank holidays for a region and year, as gov.uk publishes them.",
          "section": "working-days",
          "from": "dates-basics",
          "version": "1.0.1",
          "summary": "UK bank and public holidays for a region and year, as published by gov.uk, including one-off holidays.",
          "status": "stable",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "bankHolidays"
          ],
          "signatures": [
            "def bank_holidays(region: UkRegion, year: int) -> List[BankHoliday]"
          ],
          "reference": "from fune.dates.bank_holidays import bank_holidays  # dates.bank-holidays@^1",
          "url": "http://www.functionalweave.com/functions/dates.bank-holidays"
        },
        {
          "id": "dates.add-business-days",
          "tier": "core",
          "why": "Moves a date by working days, skipping weekends and a holiday list.",
          "section": "working-days",
          "from": "dates-basics",
          "version": "1.0.0",
          "summary": "Move a date forward or back by working days, skipping weekends and a caller-supplied holiday list.",
          "status": "stable",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "addBusinessDays"
          ],
          "signatures": [
            "def add_business_days(iso: str, days: int, holidays: Sequence[str]) -> str"
          ],
          "reference": "from fune.dates.add_business_days import add_business_days  # dates.add-business-days@^1",
          "url": "http://www.functionalweave.com/functions/dates.add-business-days"
        },
        {
          "id": "dates.business-days-between",
          "tier": "core",
          "why": "Working days between two dates, for SLAs and notice periods.",
          "section": "working-days",
          "from": "dates-basics",
          "version": "1.0.0",
          "summary": "Working days between two dates, excluding weekends and a caller-supplied holiday list.",
          "status": "stable",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "businessDaysBetween"
          ],
          "signatures": [
            "def business_days_between(start_iso: str, end_iso: str, holidays: Sequence[str]) -> int"
          ],
          "reference": "from fune.dates.business_days_between import business_days_between  # dates.business-days-between@^1",
          "url": "http://www.functionalweave.com/functions/dates.business-days-between"
        }
      ],
      "gaps": []
    },
    {
      "key": "times",
      "title": "Times and durations",
      "purpose": "Work with times of day, durations and timestamps.",
      "from": "dates-basics",
      "members": [
        {
          "id": "time.duration",
          "tier": "optional",
          "why": "Parses and adds durations like 1h30m in whole minutes, and formats the total.",
          "section": "times",
          "from": "dates-basics",
          "version": "1.0.0",
          "summary": "Parse durations written as 1h30m, 90m or 01:30, add them up in whole minutes, and format the total.",
          "status": "stable",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "duration"
          ],
          "signatures": [
            "def duration(parts: Sequence[str]) -> Duration"
          ],
          "reference": "from fune.time.duration import duration  # time.duration@^1",
          "url": "http://www.functionalweave.com/functions/time.duration"
        },
        {
          "id": "time.minutes-between",
          "tier": "optional",
          "why": "Minutes between two local date-times, across midnight.",
          "section": "times",
          "from": "dates-basics",
          "version": "1.0.0",
          "summary": "Minutes from one local date and time to another, correct across midnight; wall-clock time, no time zones.",
          "status": "stable",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "minutesBetween"
          ],
          "signatures": [
            "def minutes_between(start_date: str, start_time: str, end_date: str, end_time: str) -> int"
          ],
          "reference": "from fune.time.minutes_between import minutes_between  # time.minutes-between@^1",
          "url": "http://www.functionalweave.com/functions/time.minutes-between"
        },
        {
          "id": "time.round-to-increment",
          "tier": "optional",
          "why": "Rounds minutes to a billing increment such as 6 or 15.",
          "section": "times",
          "from": "dates-basics",
          "version": "1.0.0",
          "summary": "Round a duration in minutes to a billing increment such as 6 or 15 minutes, up, down or to nearest.",
          "status": "stable",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "roundToIncrement"
          ],
          "signatures": [
            "def round_to_increment(minutes: int, increment: int, mode: RoundingMode) -> int"
          ],
          "reference": "from fune.time.round_to_increment import round_to_increment  # time.round-to-increment@^1",
          "url": "http://www.functionalweave.com/functions/time.round-to-increment"
        },
        {
          "id": "time.iso-to-unix",
          "tier": "optional",
          "why": "RFC 3339 timestamps to Unix seconds.",
          "section": "times",
          "from": "dates-basics",
          "version": "1.0.0",
          "summary": "An RFC 3339 timestamp with a Z or offset, such as 2026-09-26T13:00:00+01:00, to Unix time in whole seconds.",
          "status": "stable",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "isoToUnix"
          ],
          "signatures": [
            "def iso_to_unix(timestamp: str) -> int"
          ],
          "reference": "from fune.time.iso_to_unix import iso_to_unix  # time.iso-to-unix@^1",
          "url": "http://www.functionalweave.com/functions/time.iso-to-unix"
        },
        {
          "id": "time.unix-to-iso",
          "tier": "optional",
          "why": "Unix seconds to an ISO 8601 UTC timestamp.",
          "section": "times",
          "from": "dates-basics",
          "version": "1.0.0",
          "summary": "Unix time in seconds to an ISO 8601 UTC timestamp such as 2026-09-26T12:00:00Z, for years 0001 to 9999.",
          "status": "stable",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "unixToIso"
          ],
          "signatures": [
            "def unix_to_iso(seconds: int) -> str"
          ],
          "reference": "from fune.time.unix_to_iso import unix_to_iso  # time.unix-to-iso@^1",
          "url": "http://www.functionalweave.com/functions/time.unix-to-iso"
        },
        {
          "id": "time.countdown",
          "tier": "optional",
          "why": "Seconds left until a moment and a 4:05 style timer text.",
          "section": "times",
          "from": "dates-basics",
          "version": "1.0.0",
          "summary": "Seconds left until a Unix time, whether it has passed, and a timer text like 4:05, for tokens or retry waits.",
          "status": "stable",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "countdown"
          ],
          "signatures": [
            "def countdown(until: int, now: int) -> Countdown"
          ],
          "reference": "from fune.time.countdown import countdown  # time.countdown@^1",
          "url": "http://www.functionalweave.com/functions/time.countdown"
        }
      ],
      "gaps": []
    },
    {
      "key": "contact",
      "title": "Contact details",
      "purpose": "Check and normalise a person's contact details before storing them.",
      "from": "validation-basics",
      "members": [
        {
          "id": "validation.email",
          "tier": "core",
          "why": "Is an email address plausible, by a documented subset of RFC 5322.",
          "section": "contact",
          "from": "validation-basics",
          "version": "1.0.0",
          "summary": "Is this a plausible email address? A documented, pragmatic subset of RFC 5322, not the full grammar.",
          "status": "stable",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "isEmail"
          ],
          "signatures": [
            "def is_email(value: str) -> bool"
          ],
          "reference": "from fune.validation.email import is_email  # validation.email@^1",
          "url": "http://www.functionalweave.com/functions/validation.email"
        },
        {
          "id": "validation.phone-e164",
          "tier": "core",
          "why": "Normalises a phone number to +44… E.164 for a default country.",
          "section": "contact",
          "from": "validation-basics",
          "version": "2.0.0",
          "summary": "Normalise a phone number to E.164 (+447700900123) using a default country's trunk and dialling prefixes.",
          "status": "stable",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "validatePhoneE164"
          ],
          "signatures": [
            "def validate_phone_e164(value: str, default_country: str) -> PhoneE164"
          ],
          "reference": "from fune.validation.phone_e164 import validate_phone_e164  # validation.phone-e164@^2",
          "url": "http://www.functionalweave.com/functions/validation.phone-e164"
        },
        {
          "id": "validation.uk-postcode",
          "tier": "core",
          "why": "Validates a UK postcode and puts it in canonical form.",
          "section": "contact",
          "from": "validation-basics",
          "version": "2.0.0",
          "summary": "Validate a UK postcode and normalise it to canonical upper case with one space before the inward code.",
          "status": "stable",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "validateUkPostcode"
          ],
          "signatures": [
            "def validate_uk_postcode(value: str) -> UkPostcode"
          ],
          "reference": "from fune.validation.uk_postcode import validate_uk_postcode  # validation.uk-postcode@^2",
          "url": "http://www.functionalweave.com/functions/validation.uk-postcode"
        },
        {
          "id": "text.normalise-name",
          "tier": "optional",
          "why": "Tidies a typed name: spacing and title case with Mc, O' and hyphen rules.",
          "section": "contact",
          "from": "validation-basics",
          "version": "1.0.0",
          "summary": "Tidy a personal name: trim, collapse whitespace and title-case, with Mc, Mac, O', hyphen and van/de rules.",
          "status": "stable",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "normaliseName"
          ],
          "signatures": [
            "def normalise_name(value: str) -> str"
          ],
          "reference": "from fune.text.normalise_name import normalise_name  # text.normalise-name@^1",
          "url": "http://www.functionalweave.com/functions/text.normalise-name"
        },
        {
          "id": "auth.normalise-email",
          "tier": "optional",
          "why": "Lower-cases an email's domain for storage and lookup.",
          "section": "contact",
          "from": "validation-basics",
          "version": "1.0.0",
          "summary": "Trim an email address and lower-case its domain for storage and lookup, or null if it is not a plausible address.",
          "status": "stable",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "normaliseEmail"
          ],
          "signatures": [
            "def normalise_email(value: str) -> Optional[str]"
          ],
          "reference": "from fune.auth.normalise_email import normalise_email  # auth.normalise-email@^1",
          "url": "http://www.functionalweave.com/functions/auth.normalise-email"
        }
      ],
      "gaps": []
    },
    {
      "key": "bank",
      "title": "Bank details",
      "purpose": "Check payee and customer bank details before money moves.",
      "from": "validation-basics",
      "members": [
        {
          "id": "validation.iban",
          "tier": "core",
          "why": "Checks an IBAN's mod-97 checksum and its country's length.",
          "section": "bank",
          "from": "validation-basics",
          "version": "1.0.0",
          "summary": "Check an IBAN against the ISO 13616 mod-97-10 checksum and the registered length for its country.",
          "status": "stable",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "isIban"
          ],
          "signatures": [
            "def is_iban(value: str) -> bool"
          ],
          "reference": "from fune.validation.iban import is_iban  # validation.iban@^1",
          "url": "http://www.functionalweave.com/functions/validation.iban"
        },
        {
          "id": "validation.bic",
          "tier": "optional",
          "why": "Checks a SWIFT/BIC code's format and splits it.",
          "section": "bank",
          "from": "validation-basics",
          "version": "1.0.0",
          "summary": "Check the format of a SWIFT/BIC code (8 or 11 characters) and split it into its parts.",
          "status": "stable",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "validateBic"
          ],
          "signatures": [
            "def validate_bic(value: str) -> BicCheck"
          ],
          "reference": "from fune.validation.bic import validate_bic  # validation.bic@^1",
          "url": "http://www.functionalweave.com/functions/validation.bic"
        },
        {
          "id": "validation.uk-sort-code-account",
          "tier": "optional",
          "why": "Checks a UK sort code and account number by the Vocalink modulus rules, against a table you supply.",
          "section": "bank",
          "from": "validation-basics",
          "version": "3.0.0",
          "summary": "Check a UK sort code and account number with the Vocalink/Pay.UK modulus rules, against a table you supply.",
          "status": "stable",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "validateUkSortCodeAccount"
          ],
          "signatures": [
            "def validate_uk_sort_code_account(sort_code: str, account_number: str, table: UkModulusTable) -> UkSortCodeAccount"
          ],
          "reference": "from fune.validation.uk_sort_code_account import validate_uk_sort_code_account  # validation.uk-sort-code-account@^3",
          "url": "http://www.functionalweave.com/functions/validation.uk-sort-code-account"
        },
        {
          "id": "validation.uk-modulus-table",
          "tier": "optional",
          "why": "Parses Vocalink's VALACDOS and SCSUBTAB files into that table.",
          "section": "bank",
          "from": "validation-basics",
          "version": "1.0.0",
          "summary": "Parse Vocalink's VALACDOS.txt and SCSUBTAB.txt into the table UK sort code modulus checking needs.",
          "status": "stable",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "parseUkModulusTable"
          ],
          "signatures": [
            "def parse_uk_modulus_table(valacdos: str, scsubtab: str) -> UkModulusTable"
          ],
          "reference": "from fune.validation.uk_modulus_table import parse_uk_modulus_table  # validation.uk-modulus-table@^1",
          "url": "http://www.functionalweave.com/functions/validation.uk-modulus-table"
        }
      ],
      "gaps": []
    },
    {
      "key": "check-digits",
      "title": "Identifiers and check digits",
      "purpose": "Catch mistyped reference numbers by their check digits.",
      "from": "validation-basics",
      "members": [
        {
          "id": "validation.luhn",
          "tier": "optional",
          "why": "Luhn mod-10 check, for card numbers and many reference numbers.",
          "section": "check-digits",
          "from": "validation-basics",
          "version": "1.0.0",
          "summary": "Check a digit string against the Luhn mod-10 checksum used by payment cards and many identifiers.",
          "status": "stable",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "isLuhn"
          ],
          "signatures": [
            "def is_luhn(value: str) -> bool"
          ],
          "reference": "from fune.validation.luhn import is_luhn  # validation.luhn@^1",
          "url": "http://www.functionalweave.com/functions/validation.luhn"
        },
        {
          "id": "validation.uk-company-number",
          "tier": "optional",
          "why": "Checks a Companies House number's format and prefix.",
          "section": "check-digits",
          "from": "validation-basics",
          "version": "2.0.1",
          "summary": "Check a Companies House company number's format and prefix (SC, NI, OC, LP...) and zero-pad it to eight characters.",
          "status": "stable",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "validateUkCompanyNumber"
          ],
          "signatures": [
            "def validate_uk_company_number(value: str) -> UkCompanyNumber"
          ],
          "reference": "from fune.validation.uk_company_number import validate_uk_company_number  # validation.uk-company-number@^2",
          "url": "http://www.functionalweave.com/functions/validation.uk-company-number"
        },
        {
          "id": "validation.lei",
          "tier": "optional",
          "why": "Checks a Legal Entity Identifier's check digits.",
          "section": "check-digits",
          "from": "validation-basics",
          "version": "1.0.0",
          "summary": "Check a 20-character Legal Entity Identifier against its ISO 17442 / ISO 7064 MOD 97-10 check digits.",
          "status": "stable",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "validateLei"
          ],
          "signatures": [
            "def validate_lei(value: str) -> LeiCheck"
          ],
          "reference": "from fune.validation.lei import validate_lei  # validation.lei@^1",
          "url": "http://www.functionalweave.com/functions/validation.lei"
        },
        {
          "id": "validation.gtin",
          "tier": "optional",
          "why": "Checks an EAN/UPC/GTIN barcode number.",
          "section": "check-digits",
          "from": "validation-basics",
          "version": "1.1.0",
          "summary": "Check an EAN-8, UPC-A, EAN-13 or GTIN-14 barcode number against the GS1 mod-10 check digit.",
          "status": "stable",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "validateGtin"
          ],
          "signatures": [
            "def validate_gtin(value: str) -> GtinCheck"
          ],
          "reference": "from fune.validation.gtin import validate_gtin  # validation.gtin@^1",
          "url": "http://www.functionalweave.com/functions/validation.gtin"
        }
      ],
      "gaps": []
    },
    {
      "key": "masking",
      "title": "Displaying sensitive values",
      "purpose": "Show stored identifiers without exposing them.",
      "from": "validation-basics",
      "members": [
        {
          "id": "text.mask",
          "tier": "optional",
          "why": "Masks all but the last digits of a card, account or phone number.",
          "section": "masking",
          "from": "validation-basics",
          "version": "1.0.0",
          "summary": "Mask all but the last n characters of a card, account or phone number, optionally keeping separators.",
          "status": "stable",
          "license": "NOASSERTION",
          "languages": [
            "typescript",
            "python",
            "rust"
          ],
          "available": true,
          "group": false,
          "functions": [
            "mask"
          ],
          "signatures": [
            "def mask(value: str, visible: int, mask_char: str, keep_separators: bool) -> str"
          ],
          "reference": "from fune.text.mask import mask  # text.mask@^1",
          "url": "http://www.functionalweave.com/functions/text.mask"
        }
      ],
      "gaps": []
    }
  ],
  "gaps": [
    {
      "key": "deposit-protection",
      "text": "Registering deposits with a protection scheme (DPS, TDS, mydeposits) is done through their services.",
      "section": "tenancies",
      "from": "property"
    },
    {
      "key": "right-to-rent",
      "text": "Right to Rent immigration checks are a Home Office process caps does not have.",
      "section": "tenancies",
      "from": "property"
    },
    {
      "key": "property-data",
      "text": "Property listings, valuations and portal feeds (Rightmove, Zoopla, Land Registry price paid) come from data providers.",
      "section": null,
      "from": "property"
    },
    {
      "key": "maintenance-jobs",
      "text": "Maintenance requests, contractor jobs and inspections are workflow caps does not have.",
      "section": null,
      "from": "property"
    },
    {
      "key": "client-money",
      "text": "Client money accounting for agents (CMP rules, client account reconciliation) is yours.",
      "section": null,
      "from": "property"
    },
    {
      "key": "fx-rate-source",
      "text": "Where exchange rates come from: money.convert takes a rate you supply; fetching and storing daily rates (ECB, a provider's API) is yours.",
      "section": null,
      "from": "money-basics"
    },
    {
      "key": "money-storage",
      "text": "Storing amounts: the database columns (integer minor units plus a currency code) and their migrations are yours.",
      "section": null,
      "from": "money-basics"
    },
    {
      "key": "time-zones",
      "text": "Time zones and daylight saving: caps works in ISO dates, UTC and wall-clock times; converting with the IANA tz rules is yours.",
      "section": null,
      "from": "dates-basics"
    },
    {
      "key": "locale-formatting",
      "text": "Showing dates in a user's language and format (\"3 octobre 2026\"): caps returns ISO dates, not localised text.",
      "section": null,
      "from": "dates-basics"
    },
    {
      "key": "non-uk-holidays",
      "text": "Public holidays outside the UK: dates.bank-holidays is UK only; pass another country's list to the working-day functions yourself.",
      "section": null,
      "from": "dates-basics"
    },
    {
      "key": "address-lookup",
      "text": "Turning a postcode into a list of addresses (Royal Mail PAF or a lookup API) is network work and not in caps.",
      "section": null,
      "from": "validation-basics"
    },
    {
      "key": "email-deliverability",
      "text": "Whether a mailbox exists (MX lookups, a confirmation email): validation.email checks the syntax only.",
      "section": null,
      "from": "validation-basics"
    },
    {
      "key": "vocalink-data",
      "text": "The Vocalink modulus tables themselves: download them from Pay.UK under its terms; caps parses them but does not ship them.",
      "section": null,
      "from": "validation-basics"
    }
  ],
  "counts": {
    "members": 64,
    "core": 27,
    "optional": 37,
    "unreviewed": 13,
    "deprecated": [],
    "unavailable": [],
    "missing": [],
    "gaps": 13
  },
  "warnings": [
    "6 core capabilities are unreviewed - they pass their tests but await an expert's sign-off; tell the user before relying on them, and never use one silently for tax, payroll, legal, clinical or other regulated rules: property.rent-proration, property.deposit-cap, property.holding-deposit-cap, property.service-charge-apportion, property.stamp-duty, property.completion-statement",
    "7 optional capabilities are unreviewed too: property.rent-review, property.floor-area, property.council-tax-band, property.mortgage-affordability, lending.loan-payment, lending.ltv, property.rental-yield",
    "Not legal or tax advice. Stamp duty, deposit caps and council tax follow UK nations' rules on a date; check with a solicitor or tax adviser before relying on them."
  ],
  "url": "http://www.functionalweave.com/suites/property",
  "owner": null
}