Alpha. Vary is under active development and not ready for production use. Syntax, APIs, performance, and behaviour may change between releases.

Decimal

The Decimal type provides exact decimal arithmetic backed by java.math.BigDecimal. Use it instead of Float when rounding errors are unacceptable (financial calculations, invoices, rates).

from decimal import parse, from_int, round_half_up

let price = parse("19.99").unwrap()
let qty = from_int(3)
let total = price * qty                      # 59.97 (exact)
let tax = total.divide(from_int(100), 2, round_half_up)

Constructors

Function	Returns	Description
`parse(s)`	`Result[Decimal, DecimalError]`	Parse a string into a Decimal
`from_int(n)`	`Decimal`	Create a Decimal from an integer
`from_float(n)`	`Decimal`	Create from float (prefer `parse` for exact values)

Operators

Decimal supports +, -, *, and comparison operators (==, !=, <, >, <=, >=).

Division requires explicit scale and rounding mode:

let result = a.divide(b, scale, mode)
let rounded = d.quantize(scale, mode)

Rounding modes

Constant	Description
`round_half_up`	Rounds 0.5 away from zero; for invoices
`round_half_even`	Banker's rounding; minimizes bias
`round_down`	Truncate toward zero; never exceeds
`round_up`	Round away from zero; never undershoots

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