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`AdditiveCollection` not defined for` Seq`? #725

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dimitriye98 opened this issue May 27, 2017 · 2 comments
Open

`AdditiveCollection` not defined for` Seq`? #725

dimitriye98 opened this issue May 27, 2017 · 2 comments
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@dimitriye98
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@dimitriye98 dimitriye98 commented May 27, 2017

Why isn't AdditiveCollection defined for Seq itself? It makes it pretty much impossible to use sized Seqs, since all of the underlying methods require an AdditiveCollection type class.
@milessabin
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@milessabin milessabin commented May 29, 2017 •
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Seq only requires an ordering of it's elements, it doesn't require the additive behaviour that AdditiveCollection requires ... instances of the latter are defined ad hoc for concrete data types which do behave appropriately. Stream would be problematic, for instance. And there's nothing to stop someone from defining a Seq subtype with ordered-set-like behaviour.
@dimitriye98
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@dimitriye98 dimitriye98 commented May 29, 2017

Stream already has an applicable AdditiveCollection though? Stream is a LinearSeq, for which an AdditiveCollection conversion exists.
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@milessabin @dimitriye98 @joroKr21
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