I found that I miss several things in sys api.

1st is the way to verify that two lists contain the same set of values (when order does not matter). There's a dozen of ways to do it via basic api, for example:

list1.intersection(list2).size == list1.union(list2).size
list1.size == list2.size && list1.intersection(list2).size == list1.size
list1.containsAll(list2) && list2.containsAll(list1) 

but I think a single method can be useful.

Also, list equality with type checks is a constant pain:

fansh> [1,2,3].map { it.toStr } == ["1","2","3"]
false
fansh> [1,2,3].map |Int i->Str| { i.toStr } == ["1","2","3"]
true
fansh> Str[] s := [1,2,3].map { it.toStr }
[1, 2, 3]
fansh> s.typeof
sys::Obj?[]

And the last minor note - it would be great to have either sys::Str.map or sys::Str.toChars

I added a Str.chars method, that seems generally useful.

Regarding list comparisons that is really because we are lacking true set functionality. I had an proposal to add an List.isSet mode via `http://fantom.org/sidewalk/topic/884`. I still think we probably want something like that eventually maybe in 1.1, so I don't want to add anything that would conflict with those enhancements.

Can we also get a Str.fromChars(Int[])? I found myself needing that last night.

Edit: clarify method signature

I was thinking that myself if we should have that if we are going to have Str.chars

I added Str.fromChars