Things on this page are fragmentary and immature notes/thoughts of the author. Please read with your own judgement!
Fold vs Reduce¶
fold takes an initial value,
and the first invocation of the lambda you pass to it
will receive that initial value
and the first element of the collection as parameters.
reduce doesn’t take an initial value,
but instead starts with the first element of the collection as the accumulator (called sum in the following example).
0.until(3).foreach { println }0
1
2
(0 until 3).foreach{println}0
1
2
0.until(9).by(2).foreach { println }0
2
4
6
8
(0 until 9 by 2).foreach { println }0
2
4
6
8
(9 until 0 by -2).foreach { println }9
7
5
3
1
to¶
to is inclusive on both ends.
0.to(3).foreach{
println
}0
1
2
3
(0 to 3).foreach{
println
}0
1
2
3
0.to(9).by(2).foreach { println }0
2
4
6
8
(0 to 9 by 2).foreach { println }0
2
4
6
8
3.to(0).by(-1).foreach{ println }3
2
1
0