Semigroup generic over Rhs #493
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Adds support for implementing semigroup for types that can plus_equals from another type, for example vectors and slices. Fixes a bug where the semigroup implementation for `Vec` would add overhanging elements twice, i.e., `[1,2] + [1,1,1]` would result in `[2,3,2`] instead of `[2,3,1]`. This leaves one quirk where `is_zero` does not depend on `Rhs`, so Rust cannot figure out which implementation to use when two are in scope, forcing the caller to phrase it as `<R as Semigroup>::is_zero(&value)`. This only applies if `R` implements `Semigroup + Semigroup<Other>`. Signed-off-by: Moritz Hoffmann <[email protected]>
frankmcsherry
approved these changes
May 23, 2024
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Adds support for implementing semigroup for types that can
plus_equalsfrom another type, for example vectors and slices.
Fixes a bug where the semigroup implementation for
Vecwould addoverhanging elements twice, i.e.,
[1,2] + [1,1,1]would result in[2,3,2] instead of[2,3,1].This leaves one quirk where
is_zerodoes not depend onRhs, so Rustcannot figure out which implementation to use when two are in scope,
forcing the caller to phrase it as
<R as Semigroup>::is_zero(&value).This only applies if
RimplementsSemigroup + Semigroup<Other>.