I can't wait to find out the problems this creates -- more fodder for "Why PHP sucks" lists, I'm sure. Maybe they'll fix the documentation for the create_function function and remove the implication that it creates lambdas.
Well, create_function() does create a new, randomly-named function in the global scope, meaning that it will not fall out scope at any point, so that you can use it as a real lambda. And because of the way that create_function() uses a string to build the function contents, by generating a new function everytime you call it, in effect you get "real" closures too. It could most certainly be improved to be more "natural" and complete, but that's probably going to break backward-compati.... oh wait, this is PHP.
Except that without scope inheritance, the "closures" created with create_function are kind of useless, and since functions are created in the global scope and thus are not garbage collected, creating new ones each time it is called ends up eating a lot of memory. This makes create_function largely useless, I don't know anyone who uses it; it's often better to just define the function globally yourself anyway and avoid the cost of run-time parser invocation, which is the same cost as using eval. In fact, create_function is implemented in terms of eval.
So you get a bunch of drawbacks and none of the real benefits, plus misrepresentation in the documentation.
Which necessitates this patch, which includes syntax changes, of course. This can only, ahem, be better.
Uh, Visual Basic 20008/9.0 has lambda expressions built right in.
Dim mapped = New Integer() {1, 2, 3, 4}.Select(Function(n) n * 2)
Dim myFunc = Function(x) mapped.ToList.IndexOf(x)
Console.WriteLine(myFunc(4)) ' prints 1 (i.e. second element, since mapped == {2,4,6,8}
.NET (and therefore Visual Basic) has had delegates, which are basically typesafe function pointers, since 2005.
If you want real functional programming on the CLR, there's always F#, which is firmly in the ML family.
AFAIK on the CLR closures are converted into classes with a single randomly named method (and since invoking a method on a class is designed to be quite efficient, that means you shoulodn't pay much of a performance penalty). In other words, it mechanically, automatically does what Java programmers would do by hand.
