fold

Description:

[ CCode ( ordering = 2 ) ]
public virtual A fold<A> (FoldFunc<A,G> f, owned A seed)

Standard aggregation function.

It takes a function, seed and first element, returns the new seed and progress to next element when the operation repeats.

Note:

Default implementation uses foreach.

Note:

In Iterator implementation operation moves the iterator to last element in iteration. If iterator is Iterator.valid the current element will be considered as well.

Example: Find the length of the longest string in a set:

uint max_length (Gee.Traversable<string> l) {
	return l.fold<uint> ((s, maxlen) => {
			return uint.max (s.length, maxlen);
		}, 0U);
}

public void main () {
	var ts = new Gee.TreeSet<string> ();
	ts.add ("helo");
	ts.add ("goodbyte");
	ts.add ("every");
	ts.add ("day");
	foreach (string s in ts) {
		print ("%s\n", s);
	}
	print ("longest string is of length: %u\n", max_length (ts));
}

valac --pkg gee-0.8 Gee.Traversable.fold.vala