Why this foldLeft scala code does not work?
up vote
0
down vote
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The following codesnippet is upposed to get me a hash map of Map[String, (String, Int)].
def genList(xx: String) = {
Seq("one", "two", "three", "four")
}
val oriwords = Set("hello", "how", "are", "you")
val newMap = (Map[String, (String, Int)]() /: oriwords) (
(cmap, currentWord) => {
val xv = 2
genList(currentWord).map(ps => {
val src = cmap get ps
if(src == None) {
cmap + (ps -> (w, xv))
}
else {
if(src.get._2 < xv) {
cmap + (ps -> (w, xv))
}
else cmap
}
})
}
)
But I am getting the following error:
error: too many arguments for method ->: (y: B)(String, B)
cmap + (ps -> (w, xv))
^
Update: With the suggested changes that are mentioned in the answers, the above error is removed.
val newMap = (Map[String, (String, Int)]() /: oriwords) (
(cmap, currentWord) => {
val xv = 2
genList(currentWord).map(ps => {
val src = cmap get ps
if(src == None) {
cmap + (ps -> ((currentWord, xv)))
}
else {
if(src.get._2 < xv) {
cmap + (ps -> ((currentWord, xv)))
}
else cmap
}
})
}
)
But now getting a new error on the above code as follows:
error: type mismatch;
found : Seq[scala.collection.immutable.Map[String,(String, Int)]]
required: scala.collection.immutable.Map[String,(String, Int)]
genList(currentWord).map(ps => {
^
scala
edited Nov 19 at 22:42
halfer
14.2k758106
asked Nov 18 at 18:40
user3243499
72211125
add a comment |
up vote
0
down vote
favorite
The following codesnippet is upposed to get me a hash map of Map[String, (String, Int)].
def genList(xx: String) = {
Seq("one", "two", "three", "four")
}
val oriwords = Set("hello", "how", "are", "you")
val newMap = (Map[String, (String, Int)]() /: oriwords) (
(cmap, currentWord) => {
val xv = 2
genList(currentWord).map(ps => {
val src = cmap get ps
if(src == None) {
cmap + (ps -> (w, xv))
}
else {
if(src.get._2 < xv) {
cmap + (ps -> (w, xv))
}
else cmap
}
})
}
)
But I am getting the following error:
error: too many arguments for method ->: (y: B)(String, B)
cmap + (ps -> (w, xv))
^
Update: With the suggested changes that are mentioned in the answers, the above error is removed.
val newMap = (Map[String, (String, Int)]() /: oriwords) (
(cmap, currentWord) => {
val xv = 2
genList(currentWord).map(ps => {
val src = cmap get ps
if(src == None) {
cmap + (ps -> ((currentWord, xv)))
}
else {
if(src.get._2 < xv) {
cmap + (ps -> ((currentWord, xv)))
}
else cmap
}
})
}
)
But now getting a new error on the above code as follows:
error: type mismatch;
found : Seq[scala.collection.immutable.Map[String,(String, Int)]]
required: scala.collection.immutable.Map[String,(String, Int)]
genList(currentWord).map(ps => {
^
scala
edited Nov 19 at 22:42
halfer
14.2k758106
asked Nov 18 at 18:40
user3243499
72211125
1
Compiler sometimes gets confused with the implicit class that defines the->method. You're usually better off changinga -> bto(a, b). You have more errors in this code, but this should take care of the weird "too many arguments" message that you're seeing.
– slouc
Nov 18 at 19:07
2
Please do not edit your question in such a way that existing answers are invalidated. If you have a question, post a question.
– Jörg W Mittag
Nov 18 at 20:00
you are giving Map[String,[(String, Int)] as the initial value but you are iterating over list and creating map inside it so it's returning you List[Map[String,(String,Int)]].
– Raman Mishra
Nov 18 at 20:07
Every iteration of the fold,/:, needs to return aMap[_,_]butgenList()is returning aSeq[_], which you are mapping over to create aSeq[Map[_,_]], which is not what what the fold requires.
– jwvh
Nov 19 at 2:32
add a comment |
up vote
0
down vote
favorite
up vote
0
down vote
favorite
The following codesnippet is upposed to get me a hash map of Map[String, (String, Int)].
def genList(xx: String) = {
Seq("one", "two", "three", "four")
}
val oriwords = Set("hello", "how", "are", "you")
val newMap = (Map[String, (String, Int)]() /: oriwords) (
(cmap, currentWord) => {
val xv = 2
genList(currentWord).map(ps => {
val src = cmap get ps
if(src == None) {
cmap + (ps -> (w, xv))
}
else {
if(src.get._2 < xv) {
cmap + (ps -> (w, xv))
}
else cmap
}
})
}
)
But I am getting the following error:
error: too many arguments for method ->: (y: B)(String, B)
cmap + (ps -> (w, xv))
^
Update: With the suggested changes that are mentioned in the answers, the above error is removed.
val newMap = (Map[String, (String, Int)]() /: oriwords) (
(cmap, currentWord) => {
val xv = 2
genList(currentWord).map(ps => {
val src = cmap get ps
if(src == None) {
cmap + (ps -> ((currentWord, xv)))
}
else {
if(src.get._2 < xv) {
cmap + (ps -> ((currentWord, xv)))
}
else cmap
}
})
}
)
But now getting a new error on the above code as follows:
error: type mismatch;
found : Seq[scala.collection.immutable.Map[String,(String, Int)]]
required: scala.collection.immutable.Map[String,(String, Int)]
genList(currentWord).map(ps => {
^
scala
edited Nov 19 at 22:42
halfer
14.2k758106
asked Nov 18 at 18:40
user3243499
72211125
The following codesnippet is upposed to get me a hash map of Map[String, (String, Int)].
def genList(xx: String) = {
Seq("one", "two", "three", "four")
}
val oriwords = Set("hello", "how", "are", "you")
val newMap = (Map[String, (String, Int)]() /: oriwords) (
(cmap, currentWord) => {
val xv = 2
genList(currentWord).map(ps => {
val src = cmap get ps
if(src == None) {
cmap + (ps -> (w, xv))
}
else {
if(src.get._2 < xv) {
cmap + (ps -> (w, xv))
}
else cmap
}
})
}
)
But I am getting the following error:
error: too many arguments for method ->: (y: B)(String, B)
cmap + (ps -> (w, xv))
^
Update: With the suggested changes that are mentioned in the answers, the above error is removed.
val newMap = (Map[String, (String, Int)]() /: oriwords) (
(cmap, currentWord) => {
val xv = 2
genList(currentWord).map(ps => {
val src = cmap get ps
if(src == None) {
cmap + (ps -> ((currentWord, xv)))
}
else {
if(src.get._2 < xv) {
cmap + (ps -> ((currentWord, xv)))
}
else cmap
}
})
}
)
But now getting a new error on the above code as follows:
error: type mismatch;
found : Seq[scala.collection.immutable.Map[String,(String, Int)]]
required: scala.collection.immutable.Map[String,(String, Int)]
genList(currentWord).map(ps => {
^
scala
scala
edited Nov 19 at 22:42
halfer
14.2k758106
asked Nov 18 at 18:40
user3243499
72211125
edited Nov 19 at 22:42
halfer
14.2k758106
asked Nov 18 at 18:40
user3243499
72211125
edited Nov 19 at 22:42
halfer
14.2k758106
edited Nov 19 at 22:42
halfer
14.2k758106
edited Nov 19 at 22:42
halfer
14.2k758106
14.2k758106
asked Nov 18 at 18:40
user3243499
72211125
asked Nov 18 at 18:40
user3243499
72211125
asked Nov 18 at 18:40
user3243499
72211125
72211125
1
Compiler sometimes gets confused with the implicit class that defines the->method. You're usually better off changinga -> bto(a, b). You have more errors in this code, but this should take care of the weird "too many arguments" message that you're seeing.
– slouc
Nov 18 at 19:07
2
Please do not edit your question in such a way that existing answers are invalidated. If you have a question, post a question.
– Jörg W Mittag
Nov 18 at 20:00
you are giving Map[String,[(String, Int)] as the initial value but you are iterating over list and creating map inside it so it's returning you List[Map[String,(String,Int)]].
– Raman Mishra
Nov 18 at 20:07
Every iteration of the fold,/:, needs to return aMap[_,_]butgenList()is returning aSeq[_], which you are mapping over to create aSeq[Map[_,_]], which is not what what the fold requires.
– jwvh
Nov 19 at 2:32
add a comment |
1
Compiler sometimes gets confused with the implicit class that defines the->method. You're usually better off changinga -> bto(a, b). You have more errors in this code, but this should take care of the weird "too many arguments" message that you're seeing.
– slouc
Nov 18 at 19:07
2
Please do not edit your question in such a way that existing answers are invalidated. If you have a question, post a question.
– Jörg W Mittag
Nov 18 at 20:00
you are giving Map[String,[(String, Int)] as the initial value but you are iterating over list and creating map inside it so it's returning you List[Map[String,(String,Int)]].
– Raman Mishra
Nov 18 at 20:07
Every iteration of the fold,/:, needs to return aMap[_,_]butgenList()is returning aSeq[_], which you are mapping over to create aSeq[Map[_,_]], which is not what what the fold requires.
– jwvh
Nov 19 at 2:32
1
1
Compiler sometimes gets confused with the implicit class that defines the
-> method. You're usually better off changing a -> b to (a, b). You have more errors in this code, but this should take care of the weird "too many arguments" message that you're seeing.– slouc
Nov 18 at 19:07
Compiler sometimes gets confused with the implicit class that defines the
-> method. You're usually better off changing a -> b to (a, b). You have more errors in this code, but this should take care of the weird "too many arguments" message that you're seeing.– slouc
Nov 18 at 19:07
2
2
Please do not edit your question in such a way that existing answers are invalidated. If you have a question, post a question.
– Jörg W Mittag
Nov 18 at 20:00
Please do not edit your question in such a way that existing answers are invalidated. If you have a question, post a question.
– Jörg W Mittag
Nov 18 at 20:00
you are giving Map[String,[(String, Int)] as the initial value but you are iterating over list and creating map inside it so it's returning you List[Map[String,(String,Int)]].
– Raman Mishra
Nov 18 at 20:07
you are giving Map[String,[(String, Int)] as the initial value but you are iterating over list and creating map inside it so it's returning you List[Map[String,(String,Int)]].
– Raman Mishra
Nov 18 at 20:07
Every iteration of the fold,
/:, needs to return a Map[_,_] but genList() is returning a Seq[_], which you are mapping over to create a Seq[Map[_,_]], which is not what what the fold requires.– jwvh
Nov 19 at 2:32
Every iteration of the fold,
/:, needs to return a Map[_,_] but genList() is returning a Seq[_], which you are mapping over to create a Seq[Map[_,_]], which is not what what the fold requires.– jwvh
Nov 19 at 2:32
add a comment |
2 Answers
2
active
oldest
votes
up vote
2
down vote
accepted
ps -> (w, xv)
is interpreted as
ps.->(w, xv)
i.e. as passing two arguments instead of what you intend, which is passing a 2-tuple as single argument:
ps.->((w, xv))
or in operator syntax:
ps -> ((w, xv))
answered Nov 18 at 18:53
Jörg W Mittag
287k62352545
Now I am getting another error after your changes. Please help. I have updated the description with the new error.
– user3243499
Nov 18 at 19:18
add a comment |
up vote
1
down vote
You need to add an extra parenthesis as the single parenthesis is interpreted as method application:
cmap + (ps -> ((w, xv)))
which means:
cmap + (ps.->((w, xv)))
Or you can use the -> twice:
cmap + (ps -> (w -> xv))
answered Nov 18 at 18:52
Gábor Bakos
6,52592541
add a comment |
2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
2
down vote
accepted
ps -> (w, xv)
is interpreted as
ps.->(w, xv)
i.e. as passing two arguments instead of what you intend, which is passing a 2-tuple as single argument:
ps.->((w, xv))
or in operator syntax:
ps -> ((w, xv))
answered Nov 18 at 18:53
Jörg W Mittag
287k62352545
Now I am getting another error after your changes. Please help. I have updated the description with the new error.
– user3243499
Nov 18 at 19:18
add a comment |
up vote
2
down vote
accepted
ps -> (w, xv)
is interpreted as
ps.->(w, xv)
i.e. as passing two arguments instead of what you intend, which is passing a 2-tuple as single argument:
ps.->((w, xv))
or in operator syntax:
ps -> ((w, xv))
answered Nov 18 at 18:53
Jörg W Mittag
287k62352545
Now I am getting another error after your changes. Please help. I have updated the description with the new error.
– user3243499
Nov 18 at 19:18
add a comment |
up vote
2
down vote
accepted
up vote
2
down vote
accepted
ps -> (w, xv)
is interpreted as
ps.->(w, xv)
i.e. as passing two arguments instead of what you intend, which is passing a 2-tuple as single argument:
ps.->((w, xv))
or in operator syntax:
ps -> ((w, xv))
answered Nov 18 at 18:53
Jörg W Mittag
287k62352545
ps -> (w, xv)
is interpreted as
ps.->(w, xv)
i.e. as passing two arguments instead of what you intend, which is passing a 2-tuple as single argument:
ps.->((w, xv))
or in operator syntax:
ps -> ((w, xv))
answered Nov 18 at 18:53
Jörg W Mittag
287k62352545
answered Nov 18 at 18:53
Jörg W Mittag
287k62352545
answered Nov 18 at 18:53
Jörg W Mittag
287k62352545
answered Nov 18 at 18:53
Jörg W Mittag
287k62352545
287k62352545
Now I am getting another error after your changes. Please help. I have updated the description with the new error.
– user3243499
Nov 18 at 19:18
add a comment |
Now I am getting another error after your changes. Please help. I have updated the description with the new error.
– user3243499
Nov 18 at 19:18
Now I am getting another error after your changes. Please help. I have updated the description with the new error.
– user3243499
Nov 18 at 19:18
Now I am getting another error after your changes. Please help. I have updated the description with the new error.
– user3243499
Nov 18 at 19:18
add a comment |
up vote
1
down vote
You need to add an extra parenthesis as the single parenthesis is interpreted as method application:
cmap + (ps -> ((w, xv)))
which means:
cmap + (ps.->((w, xv)))
Or you can use the -> twice:
cmap + (ps -> (w -> xv))
answered Nov 18 at 18:52
Gábor Bakos
6,52592541
add a comment |
up vote
1
down vote
You need to add an extra parenthesis as the single parenthesis is interpreted as method application:
cmap + (ps -> ((w, xv)))
which means:
cmap + (ps.->((w, xv)))
Or you can use the -> twice:
cmap + (ps -> (w -> xv))
answered Nov 18 at 18:52
Gábor Bakos
6,52592541
add a comment |
up vote
1
down vote
up vote
1
down vote
You need to add an extra parenthesis as the single parenthesis is interpreted as method application:
cmap + (ps -> ((w, xv)))
which means:
cmap + (ps.->((w, xv)))
Or you can use the -> twice:
cmap + (ps -> (w -> xv))
answered Nov 18 at 18:52
Gábor Bakos
6,52592541
You need to add an extra parenthesis as the single parenthesis is interpreted as method application:
cmap + (ps -> ((w, xv)))
which means:
cmap + (ps.->((w, xv)))
Or you can use the -> twice:
cmap + (ps -> (w -> xv))
answered Nov 18 at 18:52
Gábor Bakos
6,52592541
answered Nov 18 at 18:52
Gábor Bakos
6,52592541
answered Nov 18 at 18:52
Gábor Bakos
6,52592541
answered Nov 18 at 18:52
Gábor Bakos
6,52592541
6,52592541
add a comment |
add a comment |
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1
Compiler sometimes gets confused with the implicit class that defines the
->method. You're usually better off changinga -> bto(a, b). You have more errors in this code, but this should take care of the weird "too many arguments" message that you're seeing.– slouc
Nov 18 at 19:07
2
Please do not edit your question in such a way that existing answers are invalidated. If you have a question, post a question.
– Jörg W Mittag
Nov 18 at 20:00
you are giving Map[String,[(String, Int)] as the initial value but you are iterating over list and creating map inside it so it's returning you List[Map[String,(String,Int)]].
– Raman Mishra
Nov 18 at 20:07
Every iteration of the fold,
/:, needs to return aMap[_,_]butgenList()is returning aSeq[_], which you are mapping over to create aSeq[Map[_,_]], which is not what what the fold requires.– jwvh
Nov 19 at 2:32