In python I can do this:
def f((a, b)):
return a + b
d = (1, 2)
f(d)
Here the passed in tuple is being decomposed while its being passed to f.
Right now in scala I am doing this:
def f(ab: (Int, Int)): Int = {
val (a, b) = ab
a + b
}
val d = (1, 2)
f(d)
Is there something I can do here so that the decomposition happens while the arguments are passed in? Just curious.
You can create a function and match its input with pattern matching:
scala> val f: ((Int, Int)) => Int = { case (a,b) => a+b }
f: ((Int, Int)) => Int
scala> f(1, 2)
res0: Int = 3
Or match the input of the method with the match keyword:
scala> def f(ab: (Int, Int)): Int = ab match { case (a,b) => a+b }
f: (ab: (Int, Int))Int
scala> f(1, 2)
res1: Int = 3
Another way is to use a function with two arguments and to "tuple" it:
scala> val f: (Int, Int) => Int = _+_
f: (Int, Int) => Int = <function2>
scala> val g = f.tupled // or Function.tupled(f)
g: ((Int, Int)) => Int = <function1>
scala> g(1, 2)
res10: Int = 3
// or with a method
scala> def f(a: Int, b: Int): Int = a+b
f: (a: Int, b: Int)Int
scala> val g = (f _).tupled // or Function.tupled(f _)
g: ((Int, Int)) => Int = <function1>
scala> g(1, 2)
res11: Int = 3
// or inlined
scala> val f: ((Int,Int)) => Int = Function.tupled(_+_)
f: ((Int, Int)) => Int = <function1>
scala> f(1, 2)
res12: Int = 3
Starting in Scala 3, with the improved tupled function feature:
// val tuple = (1, 2)
// def f(a: Int, b: Int): Int = a + b
f.tupled(tuple)
// 3
Play with it in Scastie
object RandomExperiments extends App{
def takeTuple(t:(Int,Int))=print (s"$t ${t._1}\n")
takeTuple(1,3)
takeTuple((1,3))
takeTuple(((1,3)))
}
prints:
(1,3) 1
(1,3) 1
(1,3) 1
