scala> import scala.util.parsing.combinator._
import scala.util.parsing.combinator._

scala> val p2 = ('t' ~ 'r' ~ 'u' ~ 'e') | ('f' ~ 'a' ~ 'l' ~ 's' ~ 'e')
<console>:10: error: value ~ is not a member of Char
       val p2 = ('t' ~ 'r' ~ 'u' ~ 'e') | ('f' ~ 'a' ~ 'l' ~ 's' ~ 'e')
                     ^

scala> "a" ~ "b"
<console>:11: error: value ~ is not a member of java.lang.String
              "a" ~ "b"
                  ^

scala> elem()
<console>:11: error: not found: value elem
              elem()
              ^

scala> import scala.util.parsing.combinator._
import scala.util.parsing.combinator._

scala> 'a' ~ 'b'
<console>:14: error: value ~ is not a member of Char
              'a' ~ 'b'
                  ^

scala> "a" ~ "b"
<console>:14: error: value ~ is not a member of java.lang.String
              "a" ~ "b"
                  ^

scala> elem('a')
<console>:14: error: not found: value elem
              elem('a')
              ^