What does “:+” mean in Scala
up vote
8
down vote
favorite
I saw some Scala code written as:
def next(): Array[String] = someVariable.next() :+ iterator.key
Where someVariable has a method next() to get the next line and the iterator is of type Iterator[String].
What does :+ mean here?
scala
edited May 12 '16 at 15:57
Peter Neyens
8,6341429
asked May 12 '16 at 14:56
jlp
4091822
add a comment |
up vote
8
down vote
favorite
I saw some Scala code written as:
def next(): Array[String] = someVariable.next() :+ iterator.key
Where someVariable has a method next() to get the next line and the iterator is of type Iterator[String].
What does :+ mean here?
scala
edited May 12 '16 at 15:57
Peter Neyens
8,6341429
asked May 12 '16 at 14:56
jlp
4091822
1
Is there some reason why you didn't just look this up in the scala doc? scala-lang.org/api/2.11.8/… The API documentation is fairly comprehensive, and my "go to" place for questions like this.
– The Archetypal Paul
May 12 '16 at 15:23
It's cool new docs (2.12) give you this nice search feature scala-lang.org/files/archive/api/2.12.0-M4/index.html?search=:+
– mfirry
May 12 '16 at 20:12
@TheArchetypalPaul the time you took to write this stuff, could have answered him in a better way...
– AZ_
May 16 at 20:12
add a comment |
up vote
8
down vote
favorite
up vote
8
down vote
favorite
I saw some Scala code written as:
def next(): Array[String] = someVariable.next() :+ iterator.key
Where someVariable has a method next() to get the next line and the iterator is of type Iterator[String].
What does :+ mean here?
scala
edited May 12 '16 at 15:57
Peter Neyens
8,6341429
asked May 12 '16 at 14:56
jlp
4091822
I saw some Scala code written as:
def next(): Array[String] = someVariable.next() :+ iterator.key
Where someVariable has a method next() to get the next line and the iterator is of type Iterator[String].
What does :+ mean here?
scala
scala
edited May 12 '16 at 15:57
Peter Neyens
8,6341429
asked May 12 '16 at 14:56
jlp
4091822
edited May 12 '16 at 15:57
Peter Neyens
8,6341429
asked May 12 '16 at 14:56
jlp
4091822
edited May 12 '16 at 15:57
Peter Neyens
8,6341429
edited May 12 '16 at 15:57
Peter Neyens
8,6341429
edited May 12 '16 at 15:57
Peter Neyens
8,6341429
8,6341429
asked May 12 '16 at 14:56
jlp
4091822
asked May 12 '16 at 14:56
jlp
4091822
asked May 12 '16 at 14:56
jlp
4091822
4091822
1
Is there some reason why you didn't just look this up in the scala doc? scala-lang.org/api/2.11.8/… The API documentation is fairly comprehensive, and my "go to" place for questions like this.
– The Archetypal Paul
May 12 '16 at 15:23
It's cool new docs (2.12) give you this nice search feature scala-lang.org/files/archive/api/2.12.0-M4/index.html?search=:+
– mfirry
May 12 '16 at 20:12
@TheArchetypalPaul the time you took to write this stuff, could have answered him in a better way...
– AZ_
May 16 at 20:12
add a comment |
1
Is there some reason why you didn't just look this up in the scala doc? scala-lang.org/api/2.11.8/… The API documentation is fairly comprehensive, and my "go to" place for questions like this.
– The Archetypal Paul
May 12 '16 at 15:23
It's cool new docs (2.12) give you this nice search feature scala-lang.org/files/archive/api/2.12.0-M4/index.html?search=:+
– mfirry
May 12 '16 at 20:12
@TheArchetypalPaul the time you took to write this stuff, could have answered him in a better way...
– AZ_
May 16 at 20:12
1
1
Is there some reason why you didn't just look this up in the scala doc? scala-lang.org/api/2.11.8/… The API documentation is fairly comprehensive, and my "go to" place for questions like this.
– The Archetypal Paul
May 12 '16 at 15:23
Is there some reason why you didn't just look this up in the scala doc? scala-lang.org/api/2.11.8/… The API documentation is fairly comprehensive, and my "go to" place for questions like this.
– The Archetypal Paul
May 12 '16 at 15:23
It's cool new docs (2.12) give you this nice search feature scala-lang.org/files/archive/api/2.12.0-M4/index.html?search=:+
– mfirry
May 12 '16 at 20:12
It's cool new docs (2.12) give you this nice search feature scala-lang.org/files/archive/api/2.12.0-M4/index.html?search=:+
– mfirry
May 12 '16 at 20:12
@TheArchetypalPaul the time you took to write this stuff, could have answered him in a better way...
– AZ_
May 16 at 20:12
@TheArchetypalPaul the time you took to write this stuff, could have answered him in a better way...
– AZ_
May 16 at 20:12
add a comment |
2 Answers
2
active
oldest
votes
up vote
17
down vote
accepted
:+ is a method on whatever type is returned by someVariable.next().
Presumably it's scala.Array.:+
A copy of this array with an element appended.
This is also a case where an IDE would help you greatly. With Intellij for example, you could use the "Quick doc" or "Jump to definition" commands on :+ and immediately find out where it came from. I've found that tooling to be invaluable in writing scala.
answered May 12 '16 at 15:01
Daenyth
23.7k862103
Thank you very much!
– jlp
May 12 '16 at 15:07
add a comment |
up vote
16
down vote
On Scala Collections there is usually :+ and +:.
Both add an element to the collection. :+ appends +: prepends.
A good reminder is, : is where the Collection goes.
There is as well colA ++: colB to concat collections, where the : side collection determines the resulting type.
But there is no :++ that would be just colA ++ colB where the result has the type of colA.
answered May 12 '16 at 15:29
Nabil A.
2,7271124
Very comprehensive and concise, thanks!
– suvayu
Oct 9 '17 at 11:00
add a comment |
2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
17
down vote
accepted
:+ is a method on whatever type is returned by someVariable.next().
Presumably it's scala.Array.:+
A copy of this array with an element appended.
This is also a case where an IDE would help you greatly. With Intellij for example, you could use the "Quick doc" or "Jump to definition" commands on :+ and immediately find out where it came from. I've found that tooling to be invaluable in writing scala.
answered May 12 '16 at 15:01
Daenyth
23.7k862103
Thank you very much!
– jlp
May 12 '16 at 15:07
add a comment |
up vote
17
down vote
accepted
:+ is a method on whatever type is returned by someVariable.next().
Presumably it's scala.Array.:+
A copy of this array with an element appended.
This is also a case where an IDE would help you greatly. With Intellij for example, you could use the "Quick doc" or "Jump to definition" commands on :+ and immediately find out where it came from. I've found that tooling to be invaluable in writing scala.
answered May 12 '16 at 15:01
Daenyth
23.7k862103
Thank you very much!
– jlp
May 12 '16 at 15:07
add a comment |
up vote
17
down vote
accepted
up vote
17
down vote
accepted
:+ is a method on whatever type is returned by someVariable.next().
Presumably it's scala.Array.:+
A copy of this array with an element appended.
This is also a case where an IDE would help you greatly. With Intellij for example, you could use the "Quick doc" or "Jump to definition" commands on :+ and immediately find out where it came from. I've found that tooling to be invaluable in writing scala.
answered May 12 '16 at 15:01
Daenyth
23.7k862103
:+ is a method on whatever type is returned by someVariable.next().
Presumably it's scala.Array.:+
A copy of this array with an element appended.
This is also a case where an IDE would help you greatly. With Intellij for example, you could use the "Quick doc" or "Jump to definition" commands on :+ and immediately find out where it came from. I've found that tooling to be invaluable in writing scala.
answered May 12 '16 at 15:01
Daenyth
23.7k862103
edited May 12 '16 at 15:25
answered May 12 '16 at 15:01
Daenyth
23.7k862103
answered May 12 '16 at 15:01
Daenyth
23.7k862103
answered May 12 '16 at 15:01
Daenyth
23.7k862103
23.7k862103
Thank you very much!
– jlp
May 12 '16 at 15:07
add a comment |
Thank you very much!
– jlp
May 12 '16 at 15:07
Thank you very much!
– jlp
May 12 '16 at 15:07
Thank you very much!
– jlp
May 12 '16 at 15:07
add a comment |
up vote
16
down vote
On Scala Collections there is usually :+ and +:.
Both add an element to the collection. :+ appends +: prepends.
A good reminder is, : is where the Collection goes.
There is as well colA ++: colB to concat collections, where the : side collection determines the resulting type.
But there is no :++ that would be just colA ++ colB where the result has the type of colA.
answered May 12 '16 at 15:29
Nabil A.
2,7271124
Very comprehensive and concise, thanks!
– suvayu
Oct 9 '17 at 11:00
add a comment |
up vote
16
down vote
On Scala Collections there is usually :+ and +:.
Both add an element to the collection. :+ appends +: prepends.
A good reminder is, : is where the Collection goes.
There is as well colA ++: colB to concat collections, where the : side collection determines the resulting type.
But there is no :++ that would be just colA ++ colB where the result has the type of colA.
answered May 12 '16 at 15:29
Nabil A.
2,7271124
Very comprehensive and concise, thanks!
– suvayu
Oct 9 '17 at 11:00
add a comment |
up vote
16
down vote
up vote
16
down vote
On Scala Collections there is usually :+ and +:.
Both add an element to the collection. :+ appends +: prepends.
A good reminder is, : is where the Collection goes.
There is as well colA ++: colB to concat collections, where the : side collection determines the resulting type.
But there is no :++ that would be just colA ++ colB where the result has the type of colA.
answered May 12 '16 at 15:29
Nabil A.
2,7271124
On Scala Collections there is usually :+ and +:.
Both add an element to the collection. :+ appends +: prepends.
A good reminder is, : is where the Collection goes.
There is as well colA ++: colB to concat collections, where the : side collection determines the resulting type.
But there is no :++ that would be just colA ++ colB where the result has the type of colA.
answered May 12 '16 at 15:29
Nabil A.
2,7271124
edited Jan 29 at 16:23
answered May 12 '16 at 15:29
Nabil A.
2,7271124
answered May 12 '16 at 15:29
Nabil A.
2,7271124
answered May 12 '16 at 15:29
Nabil A.
2,7271124
2,7271124
Very comprehensive and concise, thanks!
– suvayu
Oct 9 '17 at 11:00
add a comment |
Very comprehensive and concise, thanks!
– suvayu
Oct 9 '17 at 11:00
Very comprehensive and concise, thanks!
– suvayu
Oct 9 '17 at 11:00
Very comprehensive and concise, thanks!
– suvayu
Oct 9 '17 at 11:00
add a comment |
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1
Is there some reason why you didn't just look this up in the scala doc? scala-lang.org/api/2.11.8/… The API documentation is fairly comprehensive, and my "go to" place for questions like this.
– The Archetypal Paul
May 12 '16 at 15:23
It's cool new docs (2.12) give you this nice search feature scala-lang.org/files/archive/api/2.12.0-M4/index.html?search=:+
– mfirry
May 12 '16 at 20:12
@TheArchetypalPaul the time you took to write this stuff, could have answered him in a better way...
– AZ_
May 16 at 20:12