Le 09/11/2014 15:07, Jussi Kalliokoski a écrit :
I figured I'd throw an idea out there, now that immutable data is
starting to gain mainstream attention with JS and cowpaths are being
paved. I've recently been playing around with the idea of introducing
immutable collections as value types (as opposed to, say, instances of
something).
So at the core there would be three new value types added:
* ImmutableMap.
* ImmutableArray.
* ImmutableSet.
Why would both Array and Set be needed?
We could also introduce nice syntactic sugar, such as:
var objectKey = {};
var map = {:
[objectKey]: "foo",
"bar": "baz",
}; // ImmutableMap [ [objectKey, "foo"], ["bar", "baz"] ]
var array = [:
1,
1,
2,
3,
]; // ImmutableArray [ 1, 2, 3, 4 ]
var set = <:
1,
2,
3,
>; // ImmutableSet [ 1, 2, 3 ]
The syntax suggestions are up to debate of course, but I think the key
takeaway from this proposal should be that the immutable collection
types would be values and have an empty prototype chain.
I find ":" too discrete for readability purposes. What about # ?
That's what was proposed for records and tuples (which are pretty much
the same thing as ImmutableMap and ImmutableSet respectively)
http://wiki.ecmascript.org/doku.php?id=strawman:records
http://wiki.ecmascript.org/doku.php?id=strawman:tuples
#SyntaxBikeshed
I think this would make a worthwhile addition to the language,
especially considering functional compile-to-JS languages. With the
syntactic sugar, it would probably even render a lot of their features
irrelevant because the core of JS could provide a viable platform for
functional programming (of course one might still be happier using
abstraction layers that provide immutable APIs to the underlying
platforms, such as DOM, but then that's not a problem in the JS'
domain anymore).
It would also open the possibility of a new class of postMessage sharing
(across iframes or WebWorkers) that allows parallel reading of a complex
data structure without copying.
A use case that would benefit a lot from this would be computation of a
force-layout algorithm with real-time rendering of the graph.
David
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