How to define a function inside match block - scala

Question

Question
Is there a way to define the insert function inside the makeOrderedLeafList match block?
Problem
Since insert function is only used in makeOrderedLeafList, I would like to define it inside it. However, if placed at the bottom, an error "Unit required". Cannot place at the top as "case" is being expected.
def makeOrderedLeafList(freqs: List[(Char, Int)]): List[Leaf] = freqs match {
case List() => List()
case h :: t => insert(h, makeOrderedLeafList(t))
case _ => throw new IllegalStateException
}
//--------------------------------------------------------------------------------
// Insert Leaf in the sorted list of Leaf.
//--------------------------------------------------------------------------------
def insert(c: (Char, Int), list: List[Leaf]): List[Leaf] = list match {
case List() => List(new Leaf(c._1, c._2))
case h :: t => {
//--------------------------------------------------------------------------------
// If C:[char, counter] is smaller, prepend it to the List[Leaf].
// Otherwise, recurse call insert to find a position in the tail of the list.
//--------------------------------------------------------------------------------
if (c._2 <= h.weight) new Leaf(c._1, c._2) :: list
else h :: insert(c, t)
}
}

Answer 1

Just place it inside the case before calling it:
scala> "hello" match {
| case "hel" => 1
| case "hello" =>
| def f(i: Int): Int = {
| i * 2
| }
| f(3) // don't forget to call the function...
| }
res0: Int = 6
The right-hand side of a case expression can be any code block that returns the expected type. A code block can contain function definitions.

Answer 2

If you define you function inside the outer function call, it will create a new instance of inner function on every call of outer function.
val getInnerFuncHash = () => {
val func = (x: Int) => x + 1
func.hashCode().toString
}
println(getInnerFuncHash())
println(getInnerFuncHash())
println(getInnerFuncHash())
this will print the hashCodes for the inner functions, and will output something like,
1136974570
1030088901
2115208183
which means every call to outer function will create a new instanc eof inner function.
The same thing happens in case of defs
def getInnerFuncHash(): String = {
val func = (x: Int) => x + 1
func.hashCode().toString()
}
println(getInnerFuncHash())
println(getInnerFuncHash())
println(getInnerFuncHash())