@deckyard/money

Exact currency amounts for Jennifer, on the decimal library. An amount is an int of minor units with its ISO 4217 code, so it is exact, compares with == and stores as a plain number. Multiplying, dividing and exchanging round to whole minor units in the mode the caller names; allocate splits an amount without losing or creating a cent; amounts of different currencies never mix.

Documentation

Install

jvc add @deckyard/money

This vendors the deck to vendor/<scope>/money/. Without jvc, unpack the src/ subtree of a release archive (<scope>-money-<version>.tar.gz) there.

Usage

import "@deckyard/money/" as money;

def net as money.Money init money.parse("19.99", "EUR");
def gross as money.Money init money.multiply($net, "1.19", "half-up");
io.printf("%s EUR\n", money.format($gross));   # 23.79 EUR

for (def part in money.allocate($gross, ["1", "1", "1"])) {
    io.printf("%s ", money.format($part));      # 7.93 7.93 7.93
}

Requirements

Jennifer 0.26.0 or newer, jennifer or jennifer-tiny. No capabilities: the deck is pure computation.

Development

tools/check-all.sh                   # the full gate, as CI runs it
jennifer test src/money_test.j       # the test overlay
tools/gen-currencies.sh              # refresh the ISO 4217 table
tools/check-docs.sh                  # docs against the code
tools/pack.sh dist                   # build the release archive

Licence

LGPL-3.0-only, see LICENSE. Copyright (C) 2026 mplx <[email protected]>.

tools/check-headers.sh checks every source file's SPDX header against deck.toml.