I am trying to learn Scala, so can anyone tell me how to convert the following in scala:
for (int t = 0; true; t++)
Thank you in advance.
2
4 Answers
With imperative style you can write (as you do in Java):
var t = 0
while(true) {
t+=1
...
}
With lazy functional this could be:
def ints(n: Int = 0): Stream[Int] = Stream.cons(n, ints(n+1))
ints().map(t => ...)
Using built-in functions:
Iterator.from(0).map ( t => .... )
The common use case with such infinite structures, is to take infinite stream or iterator, perform some operations on it, and then take number of results:
Iterator.from(0).filter(t => t % 1 == 0).map(t => t*t).take(10).toList
3 Comments
Jesper
As far as I know there is no
++ method on Int in Scala, you should write t += 1 instead of t++.
Luigi Plinge
I'd use
foreach instead of map, since the latter creates a new collection, so will eat memory particularly if what you're doing is infinite, i.e. Iterator from 0 foreach { t => ... }.
om-nom-nom
@LuigiPlinge yes, I though the same (the first version of answer was with foreach), but then I though that side effects with infinite structures is a dangerous thing, especially for novice
As I mentioned in the comments, your question does not seem to make much sense - please add more detail.
For now, the closest Scala translation I can come up with would be:
Stream from 0
1 Comment
Marko Topolnik
That does much more than OP's code. I propose
while (true) :)You can use while or for.
You can use for
for(i<-0 to 100) {
println(i)
}
or you use until when you want to increment by N number
for(i <- 5 until 55 by 5) {
println(i)
}
or you better use while
var i = 0
while(true) {
...
i+=1
}
or also do-while
var i = 0
do {
...
i += 1
} while(true)
Have a look at : http://www.simplyscala.com/ and test it out by yourself
Also, in my blog I did some posts about imperative scala where I used for and while loops you can have a look there.
Comments
A simple for comprehension in scala looks mostly this way:
for (i <- 0 until 10) {
// do some stuff
}
3 Comments
ziggystar
I don't recommend telling people to use for-comprehension as a surrogate for
for loops.
tgr
I agree with you, but I thought this might be something he can start with.
Luigi Plinge
I don't see the problem; using while-loops instead seems like premature optimization. (Programming in Scala refers to for-expressions without a
yield as "for-loops", so it seems they were intended to be used as such.)
tupwards, starting from zero. But you left out the body of the loop. What is your loop supposed to do? When will it stop?