`K` is the one type parameter people change, and it was last. Naming a
history in a struct field meant writing all four to say one thing:
struct Ladder { history: History<i64, ConstantDrift, NullObserver, String> }
struct Analysis<'h> { joint: Joint<'h, i64, ConstantDrift, NullObserver, &'static str> }
Now:
struct Ladder { history: History<String> }
struct Analysis<'h> { joint: Joint<'h> }
`History<K, T, D, O>`, all four defaulted. Bounds may reference later
parameters, so `D: Drift<T> = ConstantDrift` is legal in third position.
`Joint` gains the same defaults, so `Joint<'h, String>` spells it.
72 call sites swapped, and the reorder makes most of them shorter: 18
now read `History<String>` and the `&'static str` ones read `History`.
The two turbofished builders shrink from
`HistoryBuilder::<Untimed, _, _, String>::new()` to
`HistoryBuilder::<String, Untimed>::new()`.
`Joint` keeps `O` structurally, defaulted rather than removed. #72 notes
it never touches the observer, which is true — but it borrows the whole
`&'h History<K, T, D, O>` and calls `History::resolve_terms`, so dropping
the parameter means either a view type or moving that method off
`History`. The default already buys the entire user-visible benefit,
which was the spelling.
Refs #72.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011hcFjNDmHXZF8URGLku5zZ
`Rating` already derived `PartialEq`, but that derive is only reachable
through `D: PartialEq` — and `ConstantDrift`, the crate's own only
`Drift` impl, did not satisfy it. So the derive was there and unusable.
Found by writing the comparison from a consumer's position rather than
reading the derive list.
`ConstantDrift`, `ConvergenceOptions` and `GameOptions` now derive
`PartialEq`. All three are pure configuration; comparing two is the
natural thing to want and nothing about them makes equality ambiguous.
`tests/trait_impls.rs` pins the surface, written the way the failure was
reported: a consumer struct that *holds* a `History` and derives
`Debug`. It also asserts `History`'s `Debug` summarises rather than
dumping its skill stores, so a future derive cannot quietly replace the
hand-written impl.
`Clone` on `History` stays off. It is a decision, not an omission: a
history owns every slice's skill store and arena, so cloning one is
proportional to the whole fit, and no consumer has wanted it.
Closes#76.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011hcFjNDmHXZF8URGLku5zZ
logaritmiskandClaude Opus 5