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# announcements

[ilya.gorbunov]

https://kotlinlang.slack.com/archives/general/p1461253890000557
Loop fusion is an interesting optimization, but what concerns me is that it changes the evaluation order, for example:

list.filter { predicate(it) }.map { transform(it) }

Here filter evaluates predicate for each element, and after that map performs a transform on each element passed the predicate. By fusing them into a single loop one changes an order of evaluation — now predicate and transform calls are interleaved:

list.forEach { 
    if (predicate(it)) 
        result.add(transform(it))
}