[Issue 13595] Extend std.algorithm.groupBy to support non-equivalence relations

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=13595

--- Comment #4 from hsteoh at quickfur.ath.cx ---
P.S. Due to the extra performance overhead in evaluating the predicate for
every adjacent pair of elements (and also additional logic to ensure
correctness), groupBy now takes a compile-time parameter that can be used to
get the original performance when the predicate is an equivalence relation.
This way we have the best of both worlds. :-)

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