{ "id": "accounting", "title": "Accounting and bookkeeping", "summary": "Books for a small business: invoices and credit notes, VAT, double-entry journals, payment terms and debtors, bank reconciliation and period-end.", "synonyms": [ "bookkeeping", "accounts", "accountancy", "ledger", "general ledger", "double entry", "books", "finance app", "accounting software", "sage", "xero", "quickbooks" ], "apps": [ "accounting app", "bookkeeping software", "small business accounts package", "accounts receivable system", "practice software for bookkeepers" ], "language": "typescript", "includes": [ "money-basics", "dates-basics", "uk-tax", "validation-basics" ], "includedBy": [], "caveats": [ "UK first: VAT, the VAT return and late payment interest follow UK rules; another country's tax needs its own rules.", "Calculates tax from published rules; it is not tax advice. Have an accountant check how the app uses it before anyone files a return." ], "sections": [ { "key": "invoicing", "title": "Invoicing", "purpose": "Raise invoices and credit notes whose lines, VAT and totals add up to the penny.", "from": "accounting", "members": [ { "id": "finance.invoice.calculate", "tier": "core", "why": "Totals a whole invoice: line nets, VAT per line, totals and the VAT summary by rate.", "section": "invoicing", "from": "accounting", "version": "1.0.1", "summary": "Calculate a complete invoice: line nets, VAT per line, totals and a VAT summary grouped by rate.", "status": "stable", "license": "NOASSERTION", "languages": [ "typescript", "python", "rust" ], "available": true, "group": false, "functions": [ "calculateInvoice" ], "signatures": [ "export function calculateInvoice(lines: readonly InvoiceLine[], jurisdiction: string, invoiceDate: string): Invoice" ], "reference": "import { calculateInvoice } from \"#fune/finance.invoice.calculate@^1\";", "url": "http://www.functionalweave.com/functions/finance.invoice.calculate" }, { "id": "finance.invoice.line-total", "tier": "core", "why": "Net total of one line from unit price, quantity and discount, for line editing.", "section": "invoicing", "from": "accounting", "version": "1.0.0", "summary": "Net total for one invoice line: unit price by quantity, less a discount.", "status": "stable", "license": "NOASSERTION", "languages": [ "typescript", "python", "rust" ], "available": true, "group": false, "functions": [ "lineTotal" ], "signatures": [ "export function lineTotal(unitPrice: Money, quantity: number, discountBasisPoints: number): Money" ], "reference": "import { lineTotal } from \"#fune/finance.invoice.line-total@^1\";", "url": "http://www.functionalweave.com/functions/finance.invoice.line-total" }, { "id": "finance.credit-note.calculate", "tier": "core", "why": "Credits all or part of an invoice with VAT at the original tax point's rates.", "section": "invoicing", "from": "accounting", "version": "1.0.0", "summary": "Credit note against an original invoice, by units or by amount, with VAT at the original tax point's rates.", "status": "stable", "license": "NOASSERTION", "languages": [ "typescript", "python", "rust" ], "available": true, "group": false, "functions": [ "calculateCreditNote" ], "signatures": [ "export function calculateCreditNote(originalLines: readonly InvoiceLine[], credits: readonly CreditRequest[], jurisdiction: string, originalTaxPoint: string): Invoice" ], "reference": "import { calculateCreditNote } from \"#fune/finance.credit-note.calculate@^1\";", "url": "http://www.functionalweave.com/functions/finance.credit-note.calculate" }, { "id": "dates.recurrence", "tier": "optional", "why": "Dates for recurring invoices: monthly on a day, last Friday, every two weeks.", "section": "invoicing", "from": "accounting", "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": [ "export function recurrence(rule: RecurrenceRule, startIso: string, count: number): readonly string[]" ], "reference": "import { recurrence } from \"#fune/dates.recurrence@^1\";", "url": "http://www.functionalweave.com/functions/dates.recurrence" } ], "gaps": [ { "key": "invoice-numbering", "text": "Sequential, gap-free invoice numbers per series, allocated safely under concurrency.", "section": "invoicing", "from": "accounting" }, { "key": "pdf-invoices", "text": "Rendering an invoice or statement as a PDF or printable page: caps gives the figures, not the document.", "section": "invoicing", "from": "accounting" } ] }, { "key": "vat", "title": "VAT and tax", "purpose": "Charge and account for VAT at the rate in force on each date of supply.", "from": "accounting", "members": [ { "id": "finance.tax.add-vat", "tier": "core", "why": "VAT on net prices when invoicing.", "section": "vat", "from": "accounting", "version": "1.0.1", "summary": "Add VAT to a net amount using the rate in force on the date of supply.", "status": "unreviewed", "license": "NOASSERTION", "languages": [ "typescript", "python", "rust" ], "available": true, "group": false, "functions": [ "addVat" ], "signatures": [ "export function addVat(net: Money, jurisdiction: string, category: string, onDate: string): VatBreakdown" ], "reference": "import { addVat } from \"#fune/finance.tax.add-vat@^1\";", "url": "http://www.functionalweave.com/functions/finance.tax.add-vat" }, { "id": "finance.tax.remove-vat", "tier": "core", "why": "VAT inside gross receipts and expenses when recording them.", "section": "vat", "from": "accounting", "version": "1.0.2", "summary": "Extract the VAT already included in a gross amount, using the rate in force on the date of supply.", "status": "unreviewed", "license": "NOASSERTION", "languages": [ "typescript", "python", "rust" ], "available": true, "group": false, "functions": [ "removeVat" ], "signatures": [ "export function removeVat(gross: Money, jurisdiction: string, category: string, onDate: string): VatBreakdown" ], "reference": "import { removeVat } from \"#fune/finance.tax.remove-vat@^1\";", "url": "http://www.functionalweave.com/functions/finance.tax.remove-vat" }, { "id": "finance.tax.vat-return", "tier": "core", "why": "The nine-box VAT return for a period from the categorised transactions.", "section": "vat", "from": "accounting", "version": "1.0.1", "summary": "UK nine-box VAT return totals for a period from categorised sales and purchases (VAT Notice 700/12).", "status": "unreviewed", "license": "NOASSERTION", "languages": [ "typescript", "python", "rust" ], "available": true, "group": false, "functions": [ "vatReturn" ], "signatures": [ "export function vatReturn(transactions: readonly VatTransaction[], periodStart: string, periodEnd: string): VatReturn" ], "reference": "import { vatReturn } from \"#fune/finance.tax.vat-return@^1\";", "url": "http://www.functionalweave.com/functions/finance.tax.vat-return" }, { "id": "finance.tax.vat-rate", "tier": "core", "why": "The VAT rate in force for a jurisdiction, category and date; the others look it up.", "section": "vat", "from": "uk-tax", "version": "1.2.2", "summary": "Look up the VAT rate in force for a jurisdiction, category and date.", "status": "unreviewed", "license": "NOASSERTION", "languages": [ "typescript", "python", "rust" ], "available": true, "group": false, "functions": [ "vatRate" ], "signatures": [ "export function vatRate(jurisdiction: string, category: string, onDate: string): VatRate" ], "reference": "import { vatRate } from \"#fune/finance.tax.vat-rate@^1\";", "url": "http://www.functionalweave.com/functions/finance.tax.vat-rate" }, { "id": "finance.tax.vat-flat-rate", "tier": "optional", "why": "VAT due under the Flat Rate Scheme by business sector, for small businesses on it.", "section": "vat", "from": "uk-tax", "version": "1.0.1", "summary": "UK VAT Flat Rate Scheme: VAT due on gross turnover at the sector's dated rate, limited cost rate and first-year 1% off.", "status": "unreviewed", "license": "NOASSERTION", "languages": [ "typescript", "python", "rust" ], "available": true, "group": false, "functions": [ "flatRateVat" ], "signatures": [ "export function flatRateVat(turnover: Money, sector: string, limitedCostBusiness: boolean, registrationDate: string | null, supplyDate: string): FlatRateVat" ], "reference": "import { flatRateVat } from \"#fune/finance.tax.vat-flat-rate@^1\";", "url": "http://www.functionalweave.com/functions/finance.tax.vat-flat-rate" } ], "gaps": [] }, { "key": "ledger", "title": "Ledger and journals", "purpose": "Keep double-entry books that always balance.", "from": "accounting", "members": [ { "id": "finance.ledger.journal-validate", "tier": "core", "why": "Refuses a journal that does not balance, has zero lines or mixes currencies.", "section": "ledger", "from": "accounting", "version": "1.0.0", "summary": "Check a double-entry journal: debits equal credits, no zero or two-sided lines, one currency, well-formed account codes.", "status": "stable", "license": "NOASSERTION", "languages": [ "typescript", "python", "rust" ], "available": true, "group": false, "functions": [ "validateJournal" ], "signatures": [ "export function validateJournal(lines: readonly JournalLine[], currency: string): JournalCheck" ], "reference": "import { validateJournal } from \"#fune/finance.ledger.journal-validate@^1\";", "url": "http://www.functionalweave.com/functions/finance.ledger.journal-validate" }, { "id": "finance.ledger.trial-balance", "tier": "core", "why": "Balances per account from journal lines, proving debits equal credits.", "section": "ledger", "from": "accounting", "version": "1.0.0", "summary": "Trial balance from journal lines: debit or credit balance per account, and proof that debits equal credits.", "status": "stable", "license": "NOASSERTION", "languages": [ "typescript", "python", "rust" ], "available": true, "group": false, "functions": [ "trialBalance" ], "signatures": [ "export function trialBalance(lines: readonly JournalLine[], currency: string): TrialBalance" ], "reference": "import { trialBalance } from \"#fune/finance.ledger.trial-balance@^1\";", "url": "http://www.functionalweave.com/functions/finance.ledger.trial-balance" }, { "id": "finance.accruals-prepayments", "tier": "optional", "why": "Spreads an invoice across periods by days of service, for accruals and prepayments.", "section": "ledger", "from": "accounting", "version": "1.0.0", "summary": "Split an invoice across accounting periods by days of service, for accruals, prepayments and deferred income.", "status": "stable", "license": "NOASSERTION", "languages": [ "typescript", "python", "rust" ], "available": true, "group": false, "functions": [ "allocateToPeriods" ], "signatures": [ "export function allocateToPeriods(amount: Money, serviceStart: string, serviceEnd: string, periods: readonly AccountingPeriod[]): readonly PeriodAllocation[]" ], "reference": "import { allocateToPeriods } from \"#fune/finance.accruals-prepayments@^1\";", "url": "http://www.functionalweave.com/functions/finance.accruals-prepayments" }, { "id": "finance.depreciation-straight-line", "tier": "optional", "why": "Straight-line depreciation schedule for fixed assets.", "section": "ledger", "from": "accounting", "version": "1.0.0", "summary": "Straight-line depreciation schedule whose charges sum exactly to cost less residual value.", "status": "stable", "license": "NOASSERTION", "languages": [ "typescript", "python", "rust" ], "available": true, "group": false, "functions": [ "straightLineDepreciation" ], "signatures": [ "export function straightLineDepreciation(cost: Money, residualValue: Money, years: number): readonly DepreciationPeriod[]" ], "reference": "import { straightLineDepreciation } from \"#fune/finance.depreciation-straight-line@^1\";", "url": "http://www.functionalweave.com/functions/finance.depreciation-straight-line" }, { "id": "finance.depreciation-reducing-balance", "tier": "optional", "why": "Reducing-balance depreciation schedule for fixed assets.", "section": "ledger", "from": "accounting", "version": "1.0.0", "summary": "Reducing-balance depreciation schedule at a fixed rate, writing off to the residual value in the final year.", "status": "stable", "license": "NOASSERTION", "languages": [ "typescript", "python", "rust" ], "available": true, "group": false, "functions": [ "reducingBalanceDepreciation" ], "signatures": [ "export function reducingBalanceDepreciation(cost: Money, residualValue: Money, rateBasisPoints: number, years: number): readonly DepreciationPeriod[]" ], "reference": "import { reducingBalanceDepreciation } from \"#fune/finance.depreciation-reducing-balance@^1\";", "url": "http://www.functionalweave.com/functions/finance.depreciation-reducing-balance" }, { "id": "finance.fx-revaluation", "tier": "optional", "why": "Unrealised FX gain or loss on foreign-currency balances at period end.", "section": "ledger", "from": "accounting", "version": "1.0.0", "summary": "Unrealised foreign exchange gain or loss on foreign-currency balances revalued at a period-end rate.", "status": "stable", "license": "NOASSERTION", "languages": [ "typescript", "python", "rust" ], "available": true, "group": false, "functions": [ "fxRevaluation" ], "signatures": [ "export function fxRevaluation(balances: readonly ForeignBalance[], rates: readonly ExchangeRate[], functionalCurrency: string): FxRevaluation" ], "reference": "import { fxRevaluation } from \"#fune/finance.fx-revaluation@^1\";", "url": "http://www.functionalweave.com/functions/finance.fx-revaluation" } ], "gaps": [ { "key": "chart-of-accounts", "text": "A chart of accounts (nominal codes and their types) to post to: caps validates journals, it does not ship a chart.", "section": "ledger", "from": "accounting" }, { "key": "period-locking", "text": "Closing periods, locking posted entries and an audit trail of changes.", "section": "ledger", "from": "accounting" } ] }, { "key": "payments", "title": "Payments and terms", "purpose": "Know when money is due, what discount or interest applies, and match what arrived.", "from": "accounting", "members": [ { "id": "finance.payment-terms-due-date", "tier": "core", "why": "Due date from terms like net 30, end of month or 30 days after month end.", "section": "payments", "from": "accounting", "version": "1.0.0", "summary": "Invoice due date from payment terms: net N days, end of month, N days after month end, day N of next month.", "status": "stable", "license": "NOASSERTION", "languages": [ "typescript", "python", "rust" ], "available": true, "group": false, "functions": [ "paymentDueDate" ], "signatures": [ "export function paymentDueDate(invoiceDate: string, terms: PaymentTerms): string" ], "reference": "import { paymentDueDate } from \"#fune/finance.payment-terms-due-date@^1\";", "url": "http://www.functionalweave.com/functions/finance.payment-terms-due-date" }, { "id": "finance.bank-reconcile-match", "tier": "core", "why": "Matches bank statement lines to ledger entries by amount, date window and reference.", "section": "payments", "from": "accounting", "version": "1.0.0", "summary": "Match bank statement lines to ledger entries by exact amount, a date window and reference similarity, deterministically.", "status": "stable", "license": "NOASSERTION", "languages": [ "typescript", "python", "rust" ], "available": true, "group": false, "functions": [ "matchBankLines" ], "signatures": [ "export function matchBankLines(bankLines: readonly ReconcileLine[], ledgerEntries: readonly ReconcileLine[], dateWindowDays: number, minSimilarity: number): Reconciliation" ], "reference": "import { matchBankLines } from \"#fune/finance.bank-reconcile-match@^1\";", "url": "http://www.functionalweave.com/functions/finance.bank-reconcile-match" }, { "id": "finance.early-payment-discount", "tier": "optional", "why": "Discount available on a payment date under 2/10 net 30 style terms.", "section": "payments", "from": "accounting", "version": "1.0.0", "summary": "Early settlement discount available on a payment date under \"2/10 net 30\" style terms, and the amount to pay.", "status": "stable", "license": "NOASSERTION", "languages": [ "typescript", "python", "rust" ], "available": true, "group": false, "functions": [ "earlyPaymentDiscount" ], "signatures": [ "export function earlyPaymentDiscount(invoiceTotal: Money, invoiceDate: string, terms: PaymentTerms, paymentDate: string): EarlyPaymentDiscount" ], "reference": "import { earlyPaymentDiscount } from \"#fune/finance.early-payment-discount@^1\";", "url": "http://www.functionalweave.com/functions/finance.early-payment-discount" }, { "id": "finance.late-payment-interest", "tier": "optional", "why": "Statutory late payment interest and fixed compensation on overdue UK B2B invoices.", "section": "payments", "from": "accounting", "version": "1.0.1", "summary": "UK statutory late payment interest (8% over Bank Rate) and fixed compensation under the Late Payment Act 1998.", "status": "stable", "license": "NOASSERTION", "languages": [ "typescript", "python", "rust" ], "available": true, "group": false, "functions": [ "latePaymentInterest" ], "signatures": [ "export function latePaymentInterest(debt: Money, dueDate: string, paymentDate: string): LatePaymentClaim" ], "reference": "import { latePaymentInterest } from \"#fune/finance.late-payment-interest@^1\";", "url": "http://www.functionalweave.com/functions/finance.late-payment-interest" }, { "id": "finance.uk-bank-rate", "tier": "optional", "why": "Bank of England base rate on a date, which late payment interest is set over.", "section": "payments", "from": "accounting", "version": "1.0.1", "summary": "Bank of England Bank Rate (base rate) in force on a date, from the Bank's official history since 2001.", "status": "stable", "license": "NOASSERTION", "languages": [ "typescript", "python", "rust" ], "available": true, "group": false, "functions": [ "ukBankRate" ], "signatures": [ "export function ukBankRate(onDate: string): BankRate" ], "reference": "import { ukBankRate } from \"#fune/finance.uk-bank-rate@^1\";", "url": "http://www.functionalweave.com/functions/finance.uk-bank-rate" } ], "gaps": [ { "key": "bank-feeds", "text": "Importing bank transactions (OFX, CSV, Open Banking APIs) and normalising them into statement lines.", "section": "payments", "from": "accounting" }, { "key": "payment-collection", "text": "Taking payments by card or Direct Debit through a provider (Stripe, GoCardless) and handling their webhooks.", "section": "payments", "from": "accounting" } ] }, { "key": "reports", "title": "Reports", "purpose": "Show the business where it stands.", "from": "accounting", "members": [ { "id": "finance.aged-debt", "tier": "core", "why": "Aged debtors: open invoices bucketed current, 30, 60, 90+ days overdue.", "section": "reports", "from": "accounting", "version": "1.0.0", "summary": "Aged debt report: open invoices bucketed as current, 1-30, 31-60, 61-90 and 90+ days overdue as at a date.", "status": "stable", "license": "NOASSERTION", "languages": [ "typescript", "python", "rust" ], "available": true, "group": false, "functions": [ "agedDebt" ], "signatures": [ "export function agedDebt(invoices: readonly OpenInvoice[], asAt: string, bucketDays: readonly number[], currency: string): AgedDebt" ], "reference": "import { agedDebt } from \"#fune/finance.aged-debt@^1\";", "url": "http://www.functionalweave.com/functions/finance.aged-debt" }, { "id": "finance.margin", "tier": "optional", "why": "Margin and markup on a sale, for profitability reports.", "section": "reports", "from": "accounting", "version": "1.0.0", "summary": "Profit on a sale with both the margin and the markup, so the two are never confused.", "status": "stable", "license": "NOASSERTION", "languages": [ "typescript", "python", "rust" ], "available": true, "group": false, "functions": [ "margin" ], "signatures": [ "export function margin(cost: Money, price: Money): MarginBreakdown" ], "reference": "import { margin } from \"#fune/finance.margin@^1\";", "url": "http://www.functionalweave.com/functions/finance.margin" }, { "id": "charts.bar-chart", "tier": "optional", "why": "Bar chart geometry for a monthly income or expenses chart.", "section": "reports", "from": "accounting", "version": "1.0.0", "summary": "Complete bar chart geometry as data, grouped or stacked: plot area, axes, gridlines, bar rectangles, colours, legend.", "status": "stable", "license": "NOASSERTION", "languages": [ "typescript", "python", "rust" ], "available": true, "group": false, "functions": [ "barChart" ], "signatures": [ "export function barChart(spec: BarChartSpec): BarChart" ], "reference": "import { barChart } from \"#fune/charts.bar-chart@^1\";", "url": "http://www.functionalweave.com/functions/charts.bar-chart" }, { "id": "charts.line-chart", "tier": "optional", "why": "Line chart geometry for cash or revenue over time.", "section": "reports", "from": "accounting", "version": "1.0.0", "summary": "Complete line chart geometry as data: plot area, number or date axes, gridlines, series paths, colours, legend.", "status": "stable", "license": "NOASSERTION", "languages": [ "typescript", "python", "rust" ], "available": true, "group": false, "functions": [ "lineChart" ], "signatures": [ "export function lineChart(spec: LineChartSpec): LineChart" ], "reference": "import { lineChart } from \"#fune/charts.line-chart@^1\";", "url": "http://www.functionalweave.com/functions/charts.line-chart" } ], "gaps": [ { "key": "financial-statements", "text": "Profit and loss and balance sheet: caps gives the trial balance; mapping accounts to statement lines is yours.", "section": "reports", "from": "accounting" } ] }, { "key": "forms", "title": "Data entry (React)", "purpose": "Accessible forms for entering invoices and customers, in a React front end.", "from": "accounting", "members": [ { "id": "react.form.text-field", "tier": "optional", "why": "Labelled text inputs with hints and errors for invoice and customer fields.", "section": "forms", "from": "accounting", "version": "1.0.1", "summary": "A labelled single-line text input with hint, error message, autocomplete, prefix and suffix (GOV.UK text input).", "status": "stable", "license": "NOASSERTION", "languages": [ "typescript" ], "available": true, "framework": { "name": "react", "range": "^19" }, "group": false, "functions": [ "TextField" ], "signatures": [ "export function TextField(props: TextFieldProps): JSX.Element" ], "reference": "import { TextField } from \"#fune/react.form.text-field@^1\";", "url": "http://www.functionalweave.com/functions/react.form.text-field" }, { "id": "react.form.date-input", "tier": "optional", "why": "Day, month and year boxes for invoice and due dates.", "section": "forms", "from": "accounting", "version": "1.0.1", "summary": "Day, month and year boxes under one legend, with hint, error message and the boxes in error marked (GOV.UK date input).", "status": "stable", "license": "NOASSERTION", "languages": [ "typescript" ], "available": true, "framework": { "name": "react", "range": "^19" }, "group": false, "functions": [ "DateInput" ], "signatures": [ "export function DateInput(props: DateInputProps): JSX.Element" ], "reference": "import { DateInput } from \"#fune/react.form.date-input@^1\";", "url": "http://www.functionalweave.com/functions/react.form.date-input" }, { "id": "react.form.error-summary", "tier": "optional", "why": "The \"There is a problem\" box linking to each field in error.", "section": "forms", "from": "accounting", "version": "1.0.1", "summary": "A \"There is a problem\" box linking to each field in error, focused on arrival, built from a validator's fields (GOV.UK).", "status": "stable", "license": "NOASSERTION", "languages": [ "typescript" ], "available": true, "framework": { "name": "react", "range": "^19" }, "group": true, "functions": [ "errorSummaryItems", "ErrorSummary" ], "signatures": [ "export function errorSummaryItems(fields: Readonly>, order: readonly string[], targets: Readonly>): readonly ErrorSummaryItem[]", "export function ErrorSummary(props: ErrorSummaryProps): JSX.Element" ], "reference": "import { errorSummaryItems, ErrorSummary } from \"#fune/react.form.error-summary@^1\";", "url": "http://www.functionalweave.com/functions/react.form.error-summary" } ], "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": [ "export function money(minor: number, currency: string): Money" ], "reference": "import { money } from \"#fune/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": [ "export function addMoney(a: Money, b: Money): Money" ], "reference": "import { addMoney } from \"#fune/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": [ "export function sumMoney(amounts: readonly Money[], currency: string): Money" ], "reference": "import { sumMoney } from \"#fune/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": [ "export function compareMoney(a: Money, b: Money): number", "export function minMoney(a: Money, b: Money): Money", "export function maxMoney(a: Money, b: Money): Money", "export function clampMoney(amount: Money, min: Money, max: Money): Money" ], "reference": "import { compareMoney, minMoney, maxMoney, clampMoney } from \"#fune/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": [ "export function applyRate(amount: Money, basisPoints: number, mode: RoundingMode): Money" ], "reference": "import { applyRate } from \"#fune/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": [ "export function roundDiv(numerator: number, denominator: number, mode: RoundingMode): number" ], "reference": "import { roundDiv } from \"#fune/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": [ "export function convertRate(value: string, fromUnit: RateUnit, toUnit: RateUnit): string", "export function toBasisPoints(value: string, unit: RateUnit): number", "export function fromBasisPoints(basisPoints: number, unit: RateUnit): string" ], "reference": "import { convertRate, toBasisPoints, fromBasisPoints } from \"#fune/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": [ "export function percentChange(fromValue: number, toValue: number, mode: RoundingMode): number | null" ], "reference": "import { percentChange } from \"#fune/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": [ "export function calculateRational(a: Rational, op: RationalOp, b: Rational): Rational", "export function rational(numerator: number, denominator: number): Rational", "export function addRational(a: Rational, b: Rational): Rational", "export function subtractRational(a: Rational, b: Rational): Rational", "export function multiplyRational(a: Rational, b: Rational): Rational", "export function divideRational(a: Rational, b: Rational): Rational", "export function compareRational(a: Rational, b: Rational): number", "export function rationalToInteger(r: Rational, mode: RoundingMode): number" ], "reference": "import { calculateRational, rational, addRational, subtractRational, multiplyRational, divideRational, compareRational, rationalToInteger } from \"#fune/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": [ "export function roundDivBig(numerator: string, denominator: string, mode: RoundingMode): string" ], "reference": "import { roundDivBig } from \"#fune/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": [ "export function allocate(amount: Money, ratios: readonly number[]): readonly Money[]" ], "reference": "import { allocate } from \"#fune/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": [ "export function splitEven(amount: Money, parts: number): readonly Money[]" ], "reference": "import { splitEven } from \"#fune/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": [ "export function formatMoney(amount: Money): string" ], "reference": "import { formatMoney } from \"#fune/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": [ "export function parseMoney(text: string, currency: string, style: NumberStyle): Money" ], "reference": "import { parseMoney } from \"#fune/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": [ "export function currencyDigits(currency: string): number" ], "reference": "import { currencyDigits } from \"#fune/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": [ "export function convertMoney(amount: Money, rate: ExchangeRate, mode: RoundingMode): Money" ], "reference": "import { convertMoney } from \"#fune/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": [ "export function addDays(iso: string, days: number): string" ], "reference": "import { addDays } from \"#fune/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": [ "export function addMonths(iso: string, months: number): string" ], "reference": "import { addMonths } from \"#fune/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": [ "export function daysBetween(startIso: string, endIso: string): number" ], "reference": "import { daysBetween } from \"#fune/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": [ "export function monthBoundaries(iso: string): MonthBoundaries" ], "reference": "import { monthBoundaries } from \"#fune/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": [ "export function dayOfWeek(iso: string): number" ], "reference": "import { dayOfWeek } from \"#fune/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": [ "export function isLeapYear(year: number): boolean" ], "reference": "import { isLeapYear } from \"#fune/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": [ "export function overlapDays(aStart: string, aEnd: string, bStart: string, bEnd: string, endInclusive: boolean): number" ], "reference": "import { overlapDays } from \"#fune/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": [ "export function age(birthDate: string, onDate: string): number" ], "reference": "import { age } from \"#fune/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": [ "export function quarter(iso: string, fiscalYearStartMonth: number): Quarter" ], "reference": "import { quarter } from \"#fune/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": [ "export function weekNumber(iso: string): IsoWeek" ], "reference": "import { weekNumber } from \"#fune/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": [ "export function dayCountFraction(startIso: string, endIso: string, convention: DayCountConvention): YearFraction" ], "reference": "import { dayCountFraction } from \"#fune/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": [ "export function bankHolidays(region: UkRegion, year: number): readonly BankHoliday[]" ], "reference": "import { bankHolidays } from \"#fune/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": [ "export function addBusinessDays(iso: string, days: number, holidays: readonly string[]): string" ], "reference": "import { addBusinessDays } from \"#fune/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": [ "export function businessDaysBetween(startIso: string, endIso: string, holidays: readonly string[]): number" ], "reference": "import { businessDaysBetween } from \"#fune/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": [ "export function duration(parts: readonly string[]): Duration" ], "reference": "import { duration } from \"#fune/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": [ "export function minutesBetween(startDate: string, startTime: string, endDate: string, endTime: string): number" ], "reference": "import { minutesBetween } from \"#fune/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": [ "export function roundToIncrement(minutes: number, increment: number, mode: RoundingMode): number" ], "reference": "import { roundToIncrement } from \"#fune/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": [ "export function isoToUnix(timestamp: string): number" ], "reference": "import { isoToUnix } from \"#fune/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": [ "export function unixToIso(seconds: number): string" ], "reference": "import { unixToIso } from \"#fune/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": [ "export function countdown(until: number, now: number): Countdown" ], "reference": "import { countdown } from \"#fune/time.countdown@^1\";", "url": "http://www.functionalweave.com/functions/time.countdown" } ], "gaps": [] }, { "key": "tax-year", "title": "Tax periods", "purpose": "Put dates into the UK periods tax is worked out over.", "from": "uk-tax", "members": [ { "id": "dates.uk-tax-year", "tier": "core", "why": "Which UK tax year (6 April to 5 April) a date falls in.", "section": "tax-year", "from": "uk-tax", "version": "1.0.0", "summary": "The UK personal tax year containing a date: 6 April to 5 April, with HMRC's label.", "status": "stable", "license": "NOASSERTION", "languages": [ "typescript", "python", "rust" ], "available": true, "group": false, "functions": [ "ukTaxYear" ], "signatures": [ "export function ukTaxYear(iso: string): UkTaxYear" ], "reference": "import { ukTaxYear } from \"#fune/dates.uk-tax-year@^1\";", "url": "http://www.functionalweave.com/functions/dates.uk-tax-year" } ], "gaps": [] }, { "key": "identifiers", "title": "Tax identifiers", "purpose": "Check the numbers HMRC and Companies House issue before storing them.", "from": "uk-tax", "members": [ { "id": "validation.uk-vat-number", "tier": "core", "why": "Checks a UK VAT registration number's checksum.", "section": "identifiers", "from": "uk-tax", "version": "1.0.0", "summary": "Check a UK VAT registration number against HMRC's mod-97 checksum, including the post-2010 9755 variant.", "status": "stable", "license": "NOASSERTION", "languages": [ "typescript", "python", "rust" ], "available": true, "group": false, "functions": [ "isUkVatNumber" ], "signatures": [ "export function isUkVatNumber(value: string): boolean" ], "reference": "import { isUkVatNumber } from \"#fune/validation.uk-vat-number@^1\";", "url": "http://www.functionalweave.com/functions/validation.uk-vat-number" }, { "id": "validation.uk-utr", "tier": "optional", "why": "Checks a Unique Taxpayer Reference's check digit.", "section": "identifiers", "from": "uk-tax", "version": "2.0.1", "summary": "Check an HMRC Unique Taxpayer Reference's modulus 11 check digit, accepting the K and spacing people type.", "status": "stable", "license": "NOASSERTION", "languages": [ "typescript", "python", "rust" ], "available": true, "group": false, "functions": [ "validateUkUtr" ], "signatures": [ "export function validateUkUtr(value: string): UkUtr" ], "reference": "import { validateUkUtr } from \"#fune/validation.uk-utr@^2\";", "url": "http://www.functionalweave.com/functions/validation.uk-utr" }, { "id": "validation.uk-company-number", "tier": "optional", "why": "Checks and pads a Companies House company number.", "section": "identifiers", "from": "uk-tax", "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": [ "export function validateUkCompanyNumber(value: string): UkCompanyNumber" ], "reference": "import { validateUkCompanyNumber } from \"#fune/validation.uk-company-number@^2\";", "url": "http://www.functionalweave.com/functions/validation.uk-company-number" } ], "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": [ "export function isEmail(value: string): boolean" ], "reference": "import { isEmail } from \"#fune/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": [ "export function validatePhoneE164(value: string, defaultCountry: string): PhoneE164" ], "reference": "import { validatePhoneE164 } from \"#fune/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": [ "export function validateUkPostcode(value: string): UkPostcode" ], "reference": "import { validateUkPostcode } from \"#fune/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": [ "export function normaliseName(value: string): string" ], "reference": "import { normaliseName } from \"#fune/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": [ "export function normaliseEmail(value: string): string | null" ], "reference": "import { normaliseEmail } from \"#fune/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": [ "export function isIban(value: string): boolean" ], "reference": "import { isIban } from \"#fune/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": [ "export function validateBic(value: string): BicCheck" ], "reference": "import { validateBic } from \"#fune/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": [ "export function validateUkSortCodeAccount(sortCode: string, accountNumber: string, table: UkModulusTable): UkSortCodeAccount" ], "reference": "import { validateUkSortCodeAccount } from \"#fune/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": [ "export function parseUkModulusTable(valacdos: string, scsubtab: string): UkModulusTable" ], "reference": "import { parseUkModulusTable } from \"#fune/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": [ "export function isLuhn(value: string): boolean" ], "reference": "import { isLuhn } from \"#fune/validation.luhn@^1\";", "url": "http://www.functionalweave.com/functions/validation.luhn" }, { "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": [ "export function validateLei(value: string): LeiCheck" ], "reference": "import { validateLei } from \"#fune/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": [ "export function validateGtin(value: string): GtinCheck" ], "reference": "import { validateGtin } from \"#fune/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": [ "export function mask(value: string, visible: number, maskChar: string, keepSeparators: boolean): string" ], "reference": "import { mask } from \"#fune/text.mask@^1\";", "url": "http://www.functionalweave.com/functions/text.mask" } ], "gaps": [] } ], "gaps": [ { "key": "invoice-numbering", "text": "Sequential, gap-free invoice numbers per series, allocated safely under concurrency.", "section": "invoicing", "from": "accounting" }, { "key": "pdf-invoices", "text": "Rendering an invoice or statement as a PDF or printable page: caps gives the figures, not the document.", "section": "invoicing", "from": "accounting" }, { "key": "chart-of-accounts", "text": "A chart of accounts (nominal codes and their types) to post to: caps validates journals, it does not ship a chart.", "section": "ledger", "from": "accounting" }, { "key": "period-locking", "text": "Closing periods, locking posted entries and an audit trail of changes.", "section": "ledger", "from": "accounting" }, { "key": "bank-feeds", "text": "Importing bank transactions (OFX, CSV, Open Banking APIs) and normalising them into statement lines.", "section": "payments", "from": "accounting" }, { "key": "payment-collection", "text": "Taking payments by card or Direct Debit through a provider (Stripe, GoCardless) and handling their webhooks.", "section": "payments", "from": "accounting" }, { "key": "financial-statements", "text": "Profit and loss and balance sheet: caps gives the trial balance; mapping accounts to statement lines is yours.", "section": "reports", "from": "accounting" }, { "key": "multi-user-access", "text": "Users, roles and permissions for a practice and its clients: see the auth suite for passwords and tokens; roles are yours.", "section": null, "from": "accounting" }, { "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": "mtd-submission", "text": "Making Tax Digital: submitting the return to HMRC's VAT API (OAuth, fraud-prevention headers, obligations) is yours; caps gives the nine boxes.", "section": null, "from": "uk-tax" }, { "key": "corporation-tax", "text": "Corporation tax and self-assessment income tax computations are not in caps.", "section": null, "from": "uk-tax" }, { "key": "vat-number-lookup", "text": "Checking that a VAT number is registered (HMRC's lookup API) is network work; caps checks the checksum only.", "section": null, "from": "uk-tax" }, { "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": 80, "core": 35, "optional": 45, "unreviewed": 5, "deprecated": [], "unavailable": [], "missing": [], "gaps": 19 }, "warnings": [ "4 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: finance.tax.add-vat, finance.tax.remove-vat, finance.tax.vat-return, finance.tax.vat-rate", "1 optional capability is unreviewed too: finance.tax.vat-flat-rate", "UK first: VAT, the VAT return and late payment interest follow UK rules; another country's tax needs its own rules.", "Calculates tax from published rules; it is not tax advice. Have an accountant check how the app uses it before anyone files a return." ], "url": "http://www.functionalweave.com/suites/accounting", "owner": null }