Scala collections: why do we need a case statement to extract values tuples in higher order functions? -

related tuple unpacking in map operations, don't understand why need case (that looks partial function me) extract values tuple, that:

arrayoftuples map {case (e1, e2) => e1.tostring + e2} 

instead of extracting in same way works in foldleft, example

def sum(list: list[int]): int = list.foldleft(0)((r,c) => r+c) 

anyway don't specify type of parameters in first case, why need case statement?

because in scala function argument lists , tuples not unified concept in haskell , other functional languages. function:

(t: (int, int)) => ... 

is not same thing function:

(e1: int, e2: int) => ... 

in first case can use pattern matching extract tuple elements, , that's done using case syntax. actually, expression:

{case (e1, e2) => ...} 

is shorthand for:

t => t match {case (e1, e2) => ...} 

there has been discussions unifying tuples , function argument lists, there complications regarding java overloading rules, , default/named arguments. so, think it's unlikely concepts ever unified in scala.