v1.1.0

Performance and documentation release. No API changes — every exported function keeps its existing name, signature, and behavior.

⚠️ Minimum Go version is now 1.18 (was 1.13)

The only change that can affect consumers. Nothing in the library uses a language feature newer than 1.13; the floor was raised so the module works with current tooling. If you build with Go 1.18 or later, no action is needed.

Performance

Conversions were treating the exported GREG_ADJUSTMENT_BEGIN/END time.Time values as numbers, calling .Year(), .Month() and .Day() on every call — each one a timezone lookup plus a full calendar decomposition. ToRD did up to six of them, and FromRD recomputed a fixed constant from scratch on every call. Those are now integer constants.

The float64 mod/quotient helpers were also replaced with exact integer floor division, and the calendar-cycle math now does one division where it previously did two.

	before	after
ToRD	416 ns	6.7 ns	−98%
FromRD	1121 ns	14.8 ns	−99%
DateToRD	323 ns	15.3 ns	−95%
IsLeapYear	71.9 ns	1.7 ns	−98%
DaysIn	72.1 ns	1.8 ns	−97%
round trip	1557 ns	20.1 ns	−99%

Still zero allocations. ProlepticToRD is ~1.9 ns slower (4.4 → 6.3 ns), the cost of exact integer math over math.Floor; the round trip is faster, which is the path that matters in practice.

Documentation

• The package doc was detached from the package clause by a stray blank line, so pkg.go.dev was showing the wrong comment. Fixed.
• README now explains the difference between the Gregorian/Julian functions and the Proleptic ones: the missing 11 days of September 1752, the Julian leap year rule before 1752 (1700 is a leap year), and that ToRD has no year 0 while ProlepticToRD does.
• Examples expanded from 6 to 14, including a package-level example so pkg.go.dev opens with runnable code.

Testing

Behavior is unchanged, and verified as such: an exhaustive round-trip test over 1.8M R.D. values (covering the Julian period, the 1752 transition, and dates BCE), plus a differential test proving the new integer helpers match the previous float64 implementations exactly. CI now runs a [1.18, stable] matrix with go vet, replacing a pin to Go 1.13.

Full changelog: v1.0.2...v1.1.0

1.0.2

Add new functions ProlepticFromRD and ProlepticToRD to disable Julian date conversions before 1752 CE

1.0.1

What's Changed

• Use Julian calendar for dates before September 14, 1752 by @Isaac-D-Cohen in #2

New Contributors

• @Isaac-D-Cohen made their first contribution in #2

Full Changelog: v1.0.0...v1.0.1

1.0.0

Initial release