Trying a bunch of different matches and patterns on Lists.

SeqOrListsMatching.scala

val emptySeq1 = Seq.empty[String]
val emptySeq2 = Seq[String]()

val someSeq1 = Seq("one")
val someSeq2 = Seq("one", "two")

// good matches a list with something, no matter the size, works by making sure the strictly empty
// is matched FIRST
def test1(s: Seq[String]) = s match {
  case errs @ Seq() => "got empty"
  case _ => "got some"
}

// bad, misses case of more than one in the list
def test2(s: Seq[String]) = s match {
  case errs @ Seq(_) => "got some"
  case _ => "got empty"
}

// bad, misses case of more than one in the list
def test3(s: Seq[String]) = s match {
  case errs @ _ :: Nil => "got some"
  case _ => "got empty"
}

// bad, misses case of more than one in the list
def test4(s: Seq[String]) = s match {
  case errs @ _ :: Nil => "got some"
  case Nil => "got empty"
}

// good matches a list with something, no matter the size
def test5(s: Seq[String]) = s match {
  case errs @ _ :: _ => "got some"
  case Nil => "got empty"
}

// pretty much the same as test5, but "hardcoded" to just work on Seqs
def test6(s: Seq[String]) = s match {
  case errs @ Seq(_, _*) => "got some"
  case Seq() => "got empty"
}

test1(emptySeq1)
test1(emptySeq2)
test1(someSeq1)
test1(someSeq2)

test2(emptySeq1)
test2(emptySeq2)
test2(someSeq1)
test2(someSeq2)

test3(emptySeq1)
test3(emptySeq2)
test3(someSeq1)
test3(someSeq2)

test4(emptySeq1)
test4(emptySeq2)
test4(someSeq1)
//test4(someSeq2) match error, missing case for handling n elements

test5(emptySeq1)
test5(emptySeq2)
test5(someSeq1)
test5(someSeq2)

test6(emptySeq1)
test6(emptySeq2)
test6(someSeq1)
test6(someSeq2)


// Conclusion: I prefer style of test5 or test6 as they are exhaustive and doesn't
// care about the matching order, so adapatable to be changed without thinking much about it
// on specific cases.