change set constructor to accept iterables?

[JeffBezanson]

#4871 suggests constructing dicts from a single iterable argument generating tuples. We should consider doing the same for sets.

While the syntax Set(1,2,3) is nice, it turns ugly when you need to convert a collection to a set, which requires Set(c...). We should avoid expanding an entire collection into an argument list just to pass its elements to a function that wants a collection anyway.

This also fits the planned construct/coerce/convert scheme, since coerce(Set, array) is more natural than coerce(Set, 1, 2, 3, ...).

[StefanKarpinski]

Writing Set[1,2,3] would be an alternative syntax. It's a slight clash with the Int[1,2,3] syntax but I believe DataArrays may already be doing something along these lines. Perhaps we should formalize the approach as a way of constructing a collection from its elements, where for non-collection types it indicates an Array element type. We probably need a Collection abstract type in Base at this point.

On Dec 1, 2013, at 2:42 AM, Jeff Bezanson notifications@github.com wrote:

#4871 suggests constructing dicts from a single iterable argument generating tuples. We should consider doing the same for sets.

While the syntax Set(1,2,3) is nice, it turns ugly when you need to convert a collection to a set, which requires Set(c...). We should avoid expanding an entire collection into an argument list just to pass its elements to a function that wants a collection anyway.

This also fits the planned construct/coerce/convert scheme, since coerce(Set, array) is more natural than coerce(Set, 1, 2, 3, ...).

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[toivoh]

It holds a certain appeal, but how would I create a vector of sets? I'm worried that such a change would break generic code along the lines of

function f{T}(::Type{T}, x, y)
    args = T[x, y]
    ...
end

[johnmyleswhite]

We’re removing the DataVector[1, 2, 3] constructor from DataArrays.

— John

On Dec 1, 2013, at 11:56 AM, Stefan Karpinski notifications@github.com wrote:

Writing Set[1,2,3] would be an alternative syntax. It's a slight clash with the Int[1,2,3] syntax but I believe DataArrays may already be doing something along these lines. Perhaps we should formalize the approach as a way of constructing a collection from its elements, where for non-collection types it indicates an Array element type. We probably need a Collection abstract type in Base at this point.

On Dec 1, 2013, at 2:42 AM, Jeff Bezanson notifications@github.com wrote:

#4871 suggests constructing dicts from a single iterable argument generating tuples. We should consider doing the same for sets.

While the syntax Set(1,2,3) is nice, it turns ugly when you need to convert a collection to a set, which requires Set(c...). We should avoid expanding an entire collection into an argument list just to pass its elements to a function that wants a collection anyway.

This also fits the planned construct/coerce/convert scheme, since coerce(Set, array) is more natural than coerce(Set, 1, 2, 3, ...).

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[kmsquire]

If generators (#4470) were implemented, xs... notation could be turned into a generator, which if efficient could be used here (and likely other places).