Fix bug in initial and rest function. Dont use array.filter function

[kiennt]

Fixed bug when using range to implement initial and rest

I dont think we should use array.filter for performance issue
Let 's consider this example

let a = []
for item in 1..100 { a += item }
a.filter { println($0); return $0 % 10 == 0 }

# println function will be called 200 times

[ankurp]

Thanks let me take a look.

[ankurp]

Not sure what the performance issue is here? If you accept an iterator you will have the println issue.

[kiennt]

Let 's consider this example

let evenFilter = { (num: Int) -> Bool in
    println(num)
    return num % 2 == 0
}


let array = [1, 4, 5, 32, 12, 2]
let b = array.filter(evenFilter)
println("b = \(b)")
# 1
# 4
# 5
# 32
# 12
# 2
# 1
# 4
# 5
# 32
# 12
# 2
# b = [4, 32, 12, 2]

It seems native filter function has a bug which make closure in filter run twice.

That 's reason I implement filter by myself.

[ankurp]

The initial and rest changes are good. Let's not create a filter and use the native array filter method as the issue you mentioned is possible even in our own implementation of filter.

[ankurp]

Seems like a bug in Swift language itself. Let me find out in the Apple developer forum. If it's a bug then we should wait for it to be fixed as swift compiler is buggy and not fully implemented yet.

[ankurp]

@kiennt You will have to pull from master and rebase. For now do you want to move the filter changes to another branch before we figure out if its a bug in swift or they are intentionally looping through the array twice. I think its a bug in filter code which Apple will fix when iOS8/Mac OS X is released.

[kiennt]

@ankurp Alright, let me extract filter change to another branch, and rebase for this pull request

[ankurp]

@kiennt Thanks

[ankurp]

👍