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Elixir trims Calendar.ISO parsing and weekday math, densifies coverage accounting
By RepoJournal · Filed · About Elixir & Phoenix · Composed from the cited sources · methodology
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Four small Elixir changes shave native instructions out of date parsing, fold configurable week starts into precomputed biases, and cut a doubled ETS scan from test coverage, with no behavior changes promised and no migrations required.
Optimize digit parsing in Calendar.ISO elixir-lang/elixir
Combining the individual ASCII digit offset subtractions into one constant subtraction per parsed field drops the number of native instructions in the JIT output, from 39 to 31 for a four-digit year and from 18 to 14 for a two-digit month, day, hour, minute, or second. The author calls the speedup tiny but real: fewer instructions, same parsed values.
Optimize Calendar.ISO weekday arithmetic elixir-lang/elixir
Weekday lookup now uses bounded reciprocal arithmetic with a remainder fallback for arbitrary signed day counts, and configurable week starts are folded into precomputed biases. The gain is small for usual inputs, but preciz reports no regressions on his machine.
Accumulate coverage counts per module elixir-lang/elixir
Mix stored one ETS row per source line and scanned the table twice per module to count covered and uncovered lines; it now accumulates module totals directly, relying on the OTP 27 guarantee that :cover.analyse(:coverage, :line) merges duplicate line entries with covered taking precedence. The change lands now because Elixir requires OTP 27 or later.
Optimize digit parsing in Calendar.ISO (#15913) elixir-lang/elixir
Barna Kovacs' commit combines individual digit ASCII offset subtractions into a single constant subtraction for each parsed field, the change described in the earlier pull request. Same parsed output, fewer per-digit operations.
Accumulate coverage counts per module (#15911) elixir-lang/elixir
Clayton Gentry's commit lands the per-module coverage accumulation, which works only against OTP 27 or later and targets Mix's coverage bookkeeping rather than user-facing mix output.
