def mulBy(by: Int)(x: Int) = x * by
val list = List(1, 2, 3)

// doesn't work
List(1, 2, 3).map(mulBy)(1)

// works
val x = List(1, 2, 3).map(mulBy)
val y = x(1)

// works
(List(1, 2, 3).map(mulBy) _)(1)

// Why?