Questions tagged [single-abstract-method]
11 questions
4
votes
2 answers
Difference between SAM and anonymous functions
I have recently stumbled upon SAM (single abstract method) concept in Java.
I program in Scala and to me, they look the same as anonymous functions (or lambdas), however my IntelliJ suggests me to either use SAM or lambdas in different…
Shibalicious
- 288
- 2
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- 14
4
votes
2 answers
Ambiguous overload even one is more specific
I have two definition of foo, and one of them is more supposedly specific
def foo(f: java.util.function.ToIntFunction[String]) = println("foo1")
def foo[T](f: String=>T) = println("foo2")
//def foo[T](f: String=>T)(implicit d: DummyImplicit) =…
SwiftMango
- 15,092
- 13
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- 136
3
votes
3 answers
Does scala cache conversions to functional interfaces
Scala 2.12 can automatically convert a lambda expression to an interface. E.g, I'm using:
import org.apache.kafka.common.serialization.{Deserializer, Serde, Serializer}
import scalapb.GeneratedMessageCompanion
class ProtoSerde[A <:…
Yair Halberstadt
- 5,733
- 28
- 60
3
votes
1 answer
Prevent a Scala trait from qualifying as a SAM type
I have a trait Modifier[-A] extends (A => Unit).
However, Scala 2.12 magic SAM syntax silently converts any lambda literal like el => foo into a Modifier because Modifier qualifies as a SAM type (rules for applicability of this syntax are here).
I…
Nikita
- 2,924
- 1
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2
votes
1 answer
Why scalac gets confused my SAM type not implementing Function when it overloads 'andThen'?
Tested with 2.13, but I presume it's been like that since 2.12 and I just had not encountered this type of problem before:
trait Extractor[-X, +Y] {
def optional :X => Option[Y] = apply
def apply(x :X) :Option[Y]
def…
Turin
- 2,208
- 15
- 23
1
vote
2 answers
Why does this Scala code pass type checking?
Consider the following Scala code.
object Q{
trait C{
def f(x: Int) : Int
}
def applyTo3(c: C) = c.f(3)
def main(args: Array[String]) = println(applyTo3(x => x+1))
}
This looks like it shouldn't compile: the function applyTo3 expects…
Gavin Lowe
- 121
- 1
- 4
1
vote
1 answer
Why do I need to put parenthesis after the name of the interface when creating an instance of a SAM interface in Kotlin?
According to Kotlin's documentation on SAM Conversions, the syntax for creating instances of SAM interfaces goes like this:
val runnable = Runnable { println("This runs in a runnable") }
It can be seen that there are no parenthesis after Runnable,…
sserrano334
- 23
- 2
1
vote
1 answer
Scala: single abstract methods without a parameter
With SAM types, we can have:
trait Sam {
def foo(i: Int): String
}
val sam : Sam = _.toString
What if my abstract method doesn't have a parameter?
Maths noob
- 1,684
- 20
- 42
1
vote
1 answer
Strange SAM rules with functions
What are exact rules for a function to be considered for Single Abstract Method conversion? In the following code there are two very similar cases, one is compiled, second is not, when compiled with Scala 2.12.4:
trait SAM {
def apply(a: Int, b:…
Suma
- 33,181
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0
votes
0 answers
Scala Single Abstract Method & Intellij
I'm just getting use to Scala Single Abstract Method which I did not know well, until I went through several blogs on Type Class.
I am able after few minutes to figure out what's going on when I see it. I wonder if there is a way in Intellij to…
MaatDeamon
- 9,532
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- 127
0
votes
1 answer
Array SAM Scala not allowed
It seems you can not initialize an Array with a SAM syntax. When I try the following...
trait A {
def num(): Int
}
trait B extends A
trait C extends A
val nums: Array[A] = Array(() => 5)
I get the following error...
:12: error: type…
uh_big_mike_boi
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