words count example in Scala? - string

Question

I see a lot of Scala tutorials with examples doing things like recrursive traversals or solving math problems. In my daily programming life I have the feeling most of my coding time is spent on mundane tasks like string manipulation, database queries and date manipulations. Is anyone interested to give an example of the a Scala version of the following perl script?
#!/usr/bin/perl
use strict;
#opens a file with on each line one word and counts the number of occurrences
# of each word, case insensitive
print "Enter the name of your file, ie myfile.txt:\n";
my $val = <STDIN>;
chomp ($val);
open (HNDL, "$val") || die "wrong filename";
my %count = ();
while ($val = <HNDL>)
{
chomp($val);
$count{lc $val}++;
}
close (HNDL);
print "Number of instances found of:\n";
foreach my $word (sort keys %count) {
print "$word\t: " . $count{$word} . " \n";
}
In summary:
ask for a filename
read the file (contains 1 word per line)
do away with line ends ( cr, lf or crlf)
lowercase the word
increment count of the word
print out each word, sorted alphabetically, and its count
TIA

Answer 1

A simple word count like that could be written as follows:
import io.Source
import java.io.FileNotFoundException
object WC {
def main(args: Array[String]) {
println("Enter the name of your file, ie myfile.txt:")
val fileName = readLine
val words = try {
Source.fromFile(fileName).getLines.toSeq.map(_.toLowerCase.trim)
} catch {
case e: FileNotFoundException =>
sys.error("No file named %s found".format(fileName))
}
val counts = words.groupBy(identity).mapValues(_.size)
println("Number of instances found of:")
for((word, count) <- counts) println("%s\t%d".format(word, count))
}
}

Answer 2

If you're going for concise/compact, you can in 2.10:
// Opens a file with one word on each line and counts
// the number of occurrences of each word (case-insensitive)
object WordCount extends App {
println("Enter the name of your file, e.g. myfile.txt: ")
val lines = util.Try{ io.Source.fromFile(readLine).getLines().toSeq } getOrElse
{ sys.error("Wrong filename.") }
println("Number of instances found of:")
lines.map(_.trim.toLowerCase).toSeq.groupBy(identity).toSeq.
map{ case (w,ws) => s"$w\t: ${ws.size}" }.sorted.foreach(println)
}

Answer 3

val lines : List[String] = List("this is line one" , "this is line 2", "this is line three")
val linesConcat : String = lines.foldRight("")( (a , b) => a + " "+ b)
linesConcat.split(" ").groupBy(identity).toList.foreach(p => println(p._1+","+p._2.size))
prints :
this,3
is,3
three,1
line,3
2,1
one,1