and here is my implementation in `FunctorFilter`: ...
# arrow-contributorst
thanh
10/15/2019, 9:22 AMand here is my implementation in `FunctorFilter`:
Copy code
. /**
* Apply a filter to a structure such that the output structure contains all instances of specified class.
*/
@Suppress("UNCHECKED_CAST")
fun <A, B> Kind<F, A>.filterIsInstance(klass: Class<B>): Kind<F, B> =
filterMap { a -> if(klass.isInstance(a)) Some(a as B) else None }i
Imran/Malic
10/15/2019, 9:44 AM@pakoito is that your intended function ?
a
aballano
10/15/2019, 9:48 AMshouldn't it be a kotlin's KClass instead?
i
Imran/Malic
10/15/2019, 9:49 AMHow does filterIsInstance look like in the stdlib?
t
thanh
10/15/2019, 9:49 AMHere it is
Copy code
/**
* Returns a list containing all elements that are instances of specified class.
*/
public fun <R> Iterable<*>.filterIsInstance(klass: Class<R>): List<R> {
return filterIsInstanceTo(ArrayList<R>(), klass)
}thanh
10/15/2019, 9:49 AMand
Copy code
/**
* Appends all elements that are instances of specified class to the given [destination].
*/
public fun <C : MutableCollection<in R>, R> Iterable<*>.filterIsInstanceTo(destination: C, klass: Class<R>): C {
@Suppress("UNCHECKED_CAST")
for (element in this) if (klass.isInstance(element)) destination.add(element as R)
return destination
}p
pakoito
10/15/2019, 1:04 PMI'm with @aballano, why not KClass?
pakoito
10/15/2019, 1:05 PMfor Java classes too, it seems
pakoito
10/15/2019, 1:05 PM(?)
pakoito
10/15/2019, 1:05 PMI'm surprised it's not inline + reified, I'm sure I'd seen
filterIsInstance<Bla>()t
thanh
10/15/2019, 1:05 PMI think
filterIsInstancefilterIsInstancep
pakoito
10/15/2019, 1:06 PMtake a Kind and returns a Kind
pakoito
10/15/2019, 1:06 PMno implicit list conversion
pakoito
10/15/2019, 1:06 PMnah I don't like the stdib one, too much runtime magic
pakoito
10/15/2019, 1:06 PMwe have filter and filterMap for this
pakoito
10/15/2019, 1:07 PMI like your initial one
t
thanh
10/15/2019, 1:14 PMI'm confused now 😄 what should I change in my implementation? Switch to KClass?
i
Imran/Malic
10/15/2019, 1:19 PMdont use the magic in the stdlib
p
pakoito
10/15/2019, 1:27 PM Copy code
/**
* Apply a filter to a structure such that the output structure contains all instances of specified class.
*/
@Suppress("UNCHECKED_CAST")
fun <A, B> Kind<F, A>.filterIsInstance(klass: Class<B>): Kind<F, B> =
filterMap { a -> if(klass.isInstance(a)) Some(a as B) else None }pakoito
10/15/2019, 1:27 PMthis works
pakoito
10/15/2019, 1:27 PMnow my question is, whether klass should be Class or KClass, and if you could test with a Java file to see which one works
pakoito
10/15/2019, 1:27 PMas a test 😄
a
aballano
10/15/2019, 1:28 PMbut the above doesn't work for him it seems, the generated extension functions are missing the right Class import
😱 1
aballano
10/15/2019, 1:28 PMi
Imran/Malic
10/15/2019, 1:30 PMMaybe a refresh would do it
t
thanh
10/15/2019, 1:34 PMI tried to clean build but it didn't work
6 Views