Skip to content

CHANGELOG.md

Latest commit

 

History

History
274 lines (191 loc) · 9.24 KB

CHANGELOG.md

File metadata and controls

274 lines (191 loc) · 9.24 KB
Raw

CHANGELOG

Unreleased

Breaking changes

  • Require Elixir 1.15 or later.

Enhancements

  • Reduce the cost of every operation that goes through the context: results that signal nothing no longer copy the context or write it back to the process dictionary, the coefficient's digit count is computed once per operation instead of up to four times, and digit counting no longer walks a ladder of bignum comparisons before falling back to its estimate. Division is ~1.9x faster, add/sub/mult/round/normalize ~1.3x, comparison of same-scale values ~1.4x, parsing ~1.2x, all with 20-30% less allocation.

  • Make Decimal.to_float/1 scale the operand with a computed shift instead of one bit at a time: ~1.6x faster for typical values and ~11x for exponents near the ends of the double range, with 96% fewer collections.

Bug fixes

  • Fix Decimal.div/2 rounding the wrong way on inexact results. The long division discarded its remainder instead of carrying it into rounding as a sticky bit, so a guard digit of 5 with a nonzero tail was treated as an exact tie (:half_even/:half_down) and a guard digit of 0 with a nonzero tail was treated as zero (:ceiling/:floor/:up). Roughly 5% of random divisions at the default precision were affected, including :ceiling/:floor returning a result on the wrong side of the true value. The same remainder is now also reflected in the :inexact flag, which was previously suppressed when the remainder was a power of ten.

  • Re-round the coefficient when a rounding carry lengthens it past the context precision. Rounding an all-nines coefficient up (e.g. 9.99 to precision 2, or Decimal.div(95, 10) at precision 1) produced a coefficient with one digit more than precision (d(1, 100, -1), d(1, 10, 0)) instead of re-rounding to exactly precision significant digits (d(1, 10, 0), d(1, 1, 1)). This affects every context operation (add, sub, mult, div) and now matches the General Decimal Arithmetic spec and Python's decimal.

v3.1.1 (2026-05-27)

Bug fixes

  • Fix Decimal.parse/2 and Decimal.new/2 rejecting inspect output for values at the context's full precision with negative exponents (e.g. Decimal.new("0.3162277660168379331998893544432719")). The :max_digits limit no longer counts non-significant leading zeros.

v3.1.0 (2026-05-08)

Enhancements

  • Decimal.new/2 now accepts an optional opts keyword list and forwards it to Decimal.parse/2, allowing callers to override :max_digits and :max_exponent when constructing a decimal from a string.

Bug fixes

  • Fix infinite loop in Decimal.to_integer/1 when the coefficient is zero and the exponent is negative (e.g. Decimal.new("0.0")). Such values now correctly convert to the integer 0.

v3.0.0 (2026-05-07)

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.

v2.4.0 (2026-05-07)

Security

  • Mitigate exponent amplification (CVE-2026-32686). Compact inputs such as 1e1000000 could force multi-second expansions during arithmetic, parsing, normalization, comparison, or formatting. Decimal.add/2 and Decimal.sub/2 now scale operands to precision + 2 digits with a sticky bit instead of materializing the full coefficient.

Enhancements

  • Add :max_digits and :max_exponent options to Decimal.parse/2 and Decimal.cast/2 to reject pathological inputs without expansion
  • Add :max_digits option to Decimal.to_string/3 to cap formatted output before materialization
  • Add :emax and :emin fields to Decimal.Context for IBM General Decimal Arithmetic-style overflow and underflow signaling
  • Optimize hot paths for large decimals: coef_length, normalize, to_integer, integer?, parsing, and large-coefficient string formatting

v2.3.0 (2024-12-13)

v2.2.0 (2024-11-13)

  • Add Decimal.gte?/2 and Decimal.lte?/2
  • Add Decimal.compare/3 and Decimal.eq?/3 with threshold as parameter

v2.1.1 (2023-04-26)

Decimal v2.1 requires Elixir v1.8+.

Bug fixes

  • Fix Decimal.compare/2 when comparing against 0

v2.1.0 (2023-04-26)

Decimal v2.1 requires Elixir v1.8+.

Enhancements

  • Improve error message from Decimal.to_integer/1 during precision loss
  • Inspect protocol implementation returns strings in the Decimal.new(...) format
  • Add Decimal.scale/1
  • Optimize Decimal.compare/2 for numbers with large exponents

Bug fixes

  • Fix Decimal.integer?/1 spec
  • Fix Decimal.integer?/1 check on 0 with >1 significant digits

v2.0.0 (2020-09-08)

Decimal v2.0 requires Elixir v1.2+.

Enhancements

  • Add Decimal.integer?/1

Breaking changes

  • Change Decimal.compare/2 to return :lt | :eq | :gt
  • Change Decimal.cast/1 to return {:ok, t} | :error
  • Change Decimal.parse/1 to return {t, binary} | :error
  • Remove :message and :result fields from Decimal.Error
  • Remove sNaN
  • Rename qNaN to NaN
  • Remove deprecated support for floats in Decimal.new/1
  • Remove deprecated Decimal.minus/1
  • Remove deprecated Decimal.plus/1
  • Remove deprecated Decimal.reduce/1
  • Remove deprecated Decimal.with_context/2, Decimal.get_context/1, Decimal.set_context/1, and Decimal.update_context/1
  • Remove deprecated Decimal.decimal?/1

Deprecations

  • Deprecate Decimal.cmp/2

v1.9.0 (2020-09-08)

Enhancements

  • Add Decimal.negate/1
  • Add Decimal.apply_context/1
  • Add Decimal.normalize/1
  • Add Decimal.Context.with/2, Decimal.Context.get/1, Decimal.Context.set/2, and Decimal.Context.update/1
  • Add Decimal.is_decimal/1

Deprecations

  • Deprecate Decimal.minus/1 in favour of the new Decimal.negate/1
  • Deprecate Decimal.plus/1 in favour of the new Decimal.apply_context/1
  • Deprecate Decimal.reduce/1 in favour of the new Decimal.normalize/1
  • Deprecate Decimal.with_context/2, Decimal.get_context/1, Decimal.set_context/2, and Decimal.update_context/1 in favour of new functions on the Decimal.Context module
  • Deprecate Decimal.decimal?/1 in favour of the new Decimal.is_decimal/1

v1.8.1 (2019-12-20)

Bug fixes

  • Fix Decimal.compare/2 with string arguments
  • Set :signal on error

v1.8.0 (2019-06-24)

Enhancements

  • Add Decimal.cast/1
  • Add Decimal.eq?/2, Decimal.gt?/2, and Decimal.lt?/2
  • Add guards to Decimal.new/3 to prevent invalid Decimal numbers

v1.7.0 (2019-02-16)

Enhancements

  • Add Decimal.sqrt/1

v1.6.0 (2018-11-22)

Enhancements

  • Support for canonical XSD representation on Decimal.to_string/2

Bugfixes

  • Fix exponent off-by-one when converting from decimal to float
  • Fix negative?/1 and positive?/1 specs

Deprecations

  • Deprecate passing float to Decimal.new/1 in favor of Decimal.from_float/1

v1.5.0 (2018-03-24)

Enhancements

  • Add Decimal.positive?/1 and Decimal.negative?/1
  • Accept integers and strings in arithmetic functions, e.g.: Decimal.add(1, "2.0")
  • Add Decimal.from_float/1

Soft deprecations (no warnings emitted)

  • Soft deprecate passing float to new/1 in favor of from_float/1

v1.4.1 (2017-10-12)

Bugfixes

  • Include the given value as part of the error reason
  • Fix :half_even :lists.last bug (empty signif)
  • Fix error message for round
  • Fix :half_down rounding error when remainder is greater than 5
  • Fix Decimal.new/1 float conversion with bigger precision than 4
  • Fix precision default value

v1.4.0 (2017-06-25)

Bugfixes

  • Fix Decimal.to_integer/1 for large coefficients
  • Fix rounding of ~0 values
  • Fix errors when comparing and adding two infinities