In the Coursera course "Functional Programming Principles in Scala" Week 1 sample assignment (https://www.coursera.org/learn/progfun1/programming/xIz9O/example-assignment) Martin Ordersky mentions in one of his comments (on line 44 of the ListsSuites.scala test) that
* In Scala, it is allowed to pass an argument to a method using the block
* syntax, i.e. `{ argument }` instead of parentheses `(argument)`.
So when assigning a function definition in Scala would it be equivalent to say:
def foo = ()
and
def foo = {}
{} or ({}) refers to block of code.
{
statement1
statement2
statement3
}
and the last statement would be returned.
scala> val x = {
| val x = 4
| x + 1
| }
x: Int = 5
While () is for one line expression.
1.invoking a method with one param
scala> def printlnme(x: String) = { println(x)}
printlnme: (x: String)Unit
scala> printlnme("using parenthesis")
using parenthesis
scala> printlnme{"using braces"}
using braces
Not with a method with multiple params,
scala> def add(x: Int, y: Int) = { x + y }
add: (x: Int, y: Int)Int
//can also be (x + y) because one line expression
//scala> def add(x: Int, y: Int) = ( x + y )
//add: (x: Int, y: Int)Int
scala> add(1, 2)
res3: Int = 3
scala> add{1, 2}
<console>:1: error: ';' expected but ',' found.
foo{1, 2}
^
2.one line expression
In this example I'm only printing the input.
scala> List(1, 2, 3).foreach { x => println(x) }
1
2
3
scala> List(1, 2, 3).foreach ( x => println(x) )
1
2
3
Or, say one line map function.
scala> List(1, 2, 3) map { _ * 3}
res11: List[Int] = List(3, 6, 9)
scala> List(1, 2, 3) map ( _ * 3 )
res12: List[Int] = List(3, 6, 9)
But () alone can not be used with multiline statements
scala> :paste
List(1, 2, 3) foreach ( x =>
val y = x * 28
println(y)
)
<console>:2: error: illegal start of simple expression
val y = x * 28
^
you still need ({}) to be able to use parenthesis for multiline.
scala> :paste
List(1, 2, 3) foreach ( x => {
val y = x * 28
println(y)
})
28
56
84