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). Attila. > On Jul 14, 2017, at 02:24, Dave Brosius <dbros...@mebigfatguy.com> 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, fo...@univ-mlv.fr wrote: >>> De: "John Rose" <john.r.r...@oracle.com> >>> À: "Rémi Forax" <fo...@univ-mlv.fr> >>> Cc: "joe darcy" <joe.da...@oracle.com>, "core-libs-dev" >>> <core-libs-dev@openjdk.java.net> >>> Envoyé: Jeudi 13 Juillet 2017 23:05:14 >>> Objet: Re: java.util.Pair >>> On Jul 13, 2017, at 1:39 PM, Remi Forax < [ mailto:fo...@univ-mlv.fr | >>> fo...@univ-mlv.fr ] > 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 >> https://modules.ceylon-lang.org/repo/1/ceylon/language/1.0.0/module-doc/Tuple.type.html >> 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: >>> [ http://en.cppreference.com/w/cpp/utility/tuple | >>> http://en.cppreference.com/w/cpp/utility/tuple ] >>> 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 >> >
