Reference · Decimals and money

money.neg

money.neg(map) -> map | error(str)

What it does

The amount with its sign flipped, in the same currency: a charge becomes a refund, a debit a credit. Zero stays zero. The one amount whose negation does not fit in minor units, the most negative, gives an error value.

Examples

let a = money.of("10.25", "USD")print(money.neg(a))print(money.neg(money.neg(a)), money.neg(money.of("-3", "EUR")))

{ amount: -10.25m, currency: "USD" }{ amount: 10.25m, currency: "USD" } { amount: 3.00m, currency: "EUR" }

Edge cases

• Negating zero gives zero, not -0.00.
• The map may be made by hand, and is read as money.of reads an amount: an int or numeric text gets the currency's decimals ("4.5" gives -4.50), and the code comes back in upper case. More decimals than the currency has is a runtime error.
• Adding an amount and its negation is the currency's zero.
• The most negative amount, -92233720368547758.08 dollars, has no positive in minor units: its negation is an error value.

print(money.neg(money.zero("USD")), money.neg({ amount: "4.5", currency: "usd" }))let a = money.of("10.25", "USD")print(money.is_zero(money.add(a, money.neg(a))))print(money.neg({ amount: "-92233720368547758.08", currency: "USD" }))

{ amount: 0.00m, currency: "USD" } { amount: -4.50m, currency: "USD" }trueerr("92233720368547758.08 USD is too large an amount")

Errors

A value that is not money, or a map with more decimals than its currency has, is a runtime error, not an error value.

print(money.neg(5))

line 1: `money.neg` expects money ({ amount, currency }) as argument 1, got int 5

print(money.neg({ amount: "4.505", currency: "USD" }))

line 1: `money.neg`: 4.505 has more decimals than USD has (2): round it first with money.round(m, mode)

Chaining

print(money.of("12.50", "USD") | money.neg | money.format)print([money.of(1, "USD"), money.of(2, "USD")] | map(money.neg) | map((m) => m.amount))

-$12.50[-1.00m, -2.00m]

See also

money.sub, money.add, money.is_zero, money.compare

Edit this page on GitHub · every example's output was made by running it (tools/refcheck.mjs) · questions on Discord or r/quillo