Attila Szegedi szegedia at
Sat Jul 15 20:11:51 UTC 2017

In application code I agree that semantics-free tuples are a code smell, but if you're developing a library of generally usable algorithms a need for a type that is a product of two types can naturally arise, without further semantics provided (or required) by the context.

In a sense the existence of BiFunction is already a validation of the need to pass pairs as function arguments; we just don't have a way to keep them rectified (or use them as a return value). 


> On Jul 14, 2017, at 02:24, Dave Brosius <dbrosius at> wrote:
> I would avoid Pair and Entry like the plague. They are devoid of meaning and are just there to save your fingers. If that is your main impetus, i'd just turn to using lombok and have true bean classes, that are finger-cost free.
> On 07/13/2017 05:41 PM, forax at wrote:
>>> De: "John Rose" <john.r.rose at>
>>> À: "Rémi Forax" <forax at>
>>> Cc: "joe darcy" <joe.darcy at>, "core-libs-dev"
>>> <core-libs-dev at>
>>> Envoyé: Jeudi 13 Juillet 2017 23:05:14
>>> Objet: Re: java.util.Pair
>>> On Jul 13, 2017, at 1:39 PM, Remi Forax < [ mailto:forax at |
>>> forax at ] > wrote:
>>>> Tuples are like an array of value types parameterized by a constant integer
>>> The homogeneous case is pretty simple; most of what you need is
>>> to allow a generic type to be parameterized by an integer. C++ templates
>>> have had that for a long time.
>>> What's harder is to have a two-step process for type instantiation:
>>> First, tell me the arity N, and second, for each position under that arity,
>>> tell me the type T[i], i<N. (And don't break type inference.) I think
>>> the most Java-like way to handle it might be type-functions that overload
>>> alongside generic types. But there are many, many ways to slice it.
>> or use a recursive definition like in Ceylon
>> and the fact that value types are flatten to specify the rest, i.e a Tuple contains a T first and a Tuple rest.
>>> C++ templates can express heterogeneous tuples:
>>> [ |
>>> ]
>>> Typically there is a small limit to C++ tuple size, because the underlying
>>> template implementation has its size set to the arity limit.
>>> — John
>> Rémi

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