[Issue 13936] groupBy must be redone

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=13936

--- Comment #14 from Andrei Alexandrescu <andrei at erdani.com> ---
(In reply to hsteoh from comment #12)
> By "it's complicated" I do not mean "it's complicated to write code for" --
> that's a non-issue. What I mean is "it introduces complicated semantics,
> which inevitably results in obscure corner cases that have
> unexpected/pathological behaviour". This includes effects of similar calibre
> as transient ranges (they technically conform 100% to the range API but have
> unusual behaviour that cannot be easily dealt with). One such effect is the
> semantics of .save.

Again: let's explore and if the semantic complications are too big we're not
nailed to the floor. I'll come up with code during the weekend.

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