Szathmáry László honlapja @ DEIK

for i in 1..5:
echo i

𝥶Closed interval. 5 is included. It prints the following values: 1, 2, 3, 4, 5

for i in 1 ..< 5:
echo i

𝥶The interval is open on the right side. 5 is not included. Printed values: 1, 2, 3, 4

It's like Python's range(1, 5).

In Nim, 1..1_000_000 is a range expression that generates values lazily, one at a time. So it's similar to Python 3's range(). It doesn't build a sequence in the memory.

countup()

You need a step and you want values in increasing order.

The task is to print these values: 2, 4, 6, 8

countup()
for i in range(2, 10, 2): print(i) In Python, the upper limit (here: 10) is not included.	for i in countup(2, 8, 2): echo i Lower limit is 2, upper limit is 8 (included), and the step is 2.

countdown()

You need a step and you want values in decreasing order.

The task is to print these values: 10, 8, 6, 4, 2

countdown()
for i in range(10, 0, -2): print(i)	for i in countdown(10, 2, 2): echo i Upper limit is 10, lower limit is 2 (included), and the step is 2.

Notice that the step is always positive! Even if you use countdown(), the step is still positive.

for loop

countup()

countdown()