It could sound like a rookie mistake but I do a lot of that. While passing lazy evaluated block or value into a function, if I forget somehow make that function's corresponding parameter lazy (pass/call by name) its causing some confusions at first glance because it forces evaluation.Very small ex;
lazy val a = {println("a");1}
def myfunc(b:Int){println("hello")}
myfunc(a);
Output:
a
Hello
So my question, is there any compiler help for this problem?(flag etc.) Or this is a kind of thing that I should take care of ?
You can move the problem into type system.
lazy val
s explicitly, instead...class Lazy[A](body: => A) {
lazy val value = body
}
object Lazy {
def apply[A](body: => A) = new Lazy[A](body)
}
Now you will have a little bit of help from the compiler:
val a = Lazy {
println("a")
1
}
def myfunc(b: Lazy[Int]) = {
println("hello")
}
myfunc(a) // ok, and it doesn't print "a" since it never uses it
// myfunc(42) // won't compile
def myfunc2(b: Int) = b + 42
// myfunc2(a) // does not compile
myfunc2(a.value) // ok, explicitly evaluate - or consider refactoring myfunc2