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learning-hour-maker/ideas/slice-with-lambda/exercise/solution/README.md
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Your Name 77ae05c28c Rename split-loop-with-lambda to slice-with-lambda
The refactoring is now published as Slice on sammancoaching.org:
https://sammancoaching.org/refactorings/slice.html

- git mv ideas/split-loop-with-lambda -> ideas/slice-with-lambda
- rename learning-hour file and update frontmatter name
- update paths in tools/rehearse scripts and report title
- update prose: 'Split Loop with Lambda' -> 'Slice with Lambda'
  in learning hour, exercise READMEs, storyboard, solution comments
- link the published Slice refactoring from the pattern draft
2026-09-29 15:47:30 +00:00

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# Reference solution — end state after step 3
Derived from [IceCreamForecasting-Refactoring-Kata](https://github.com/emilybache/IceCreamForecasting-Refactoring-Kata)
(same license as the kata applies to the copied `IceCream.java`).
Run with `mvn test` — the approval test passes deterministically without
touching the weather service.
## What changed vs the exercise start
1. Weather loop extracted to `collectExpectedWeather(LongFunction<Boolean>)`
— a static method whose only "unwanted dependency" is the lambda parameter.
2. Public no-arg `longRangeForecast()` delegates to a new overload that takes
the weather function, keeping existing callers working.
3. Test passes a pure lambda (`daysForward -> true`) — the original test
called the no-arg method and was flaky because of `Scorer`'s `Random`.
## Variations to try (for the debrief or a second round)
- `daysForward -> false` (no sunny holidays): scores drop to `+10` only.
- `daysForward -> daysForward == 5` (exactly one sunny holiday, and it is not
`expectedWeather.get(1)`, so no `+2`): all flavours `10`.
- Delete the `scorer.updateSelection()` call inside the production lambda:
the approved file does not change — the forecast never reads `Scorer.flavour`.
- Variation end state: skip the overload; make `collectExpectedWeather`
package-private and test it directly with pure lambdas. Trade-off:
tests the pure slice but not the composition (scoring loop).