decimal 3.0.0

on Hex

Note on the new defaults

The new decimal128 defaults are more than sufficient for currency and
other real-world numeric use cases. With precision: 34 and a scale of
2 (two digits after the decimal point for cents), values from 0.00 up
to roughly 99_999_999_999_999_999_999_999_999_999_999.99 (~10³², 100
nonillion) round-trip without rounding. Most upgrades from 2.x require
no code changes.

Security

• Make the v2.4.0 mitigations for CVE-2026-32686 the default. The
  default Decimal.Context and the public parse, cast, and to_string
  functions now follow IEEE 754 decimal128 limits, rejecting inputs
  such as 1e1000000000 without materializing them.

Breaking changes

• Decimal.Context defaults change from precision 28 and unbounded
  emax/emin to decimal128 values: precision: 34, emax: 6_144,
  emin: -6_143. Operation results whose adjusted exponent leaves that
  band signal overflow or underflow.
• Decimal.parse/1 and Decimal.cast/1 reject inputs whose digit count
  exceeds 34 (decimal128 precision) or whose absolute exponent exceeds
  6_144 (decimal128 emax). Use parse/2 / cast/2 with
  max_digits: :infinity and max_exponent: :infinity to restore
  unbounded behavior.
• Decimal.parse/2 and Decimal.cast/2 default :max_digits to 34
  and :max_exponent to 6_144 when not specified.
• Decimal.to_string/2 and Decimal.to_string/3 raise ArgumentError
  when the rendered output would exceed 6_178 digit characters
  (precision + emax — the worst-case :normal width of any in-range
  decimal128 value). Inspect, String.Chars, and JSON.Encoder
  protocol implementations pass max_digits: :infinity so debug output
  always succeeds.