i'm writing a simple test `testLaws(SemigroupKLaws...

# arrow

[prat]

i'm writing a simple test testLaws(SemigroupKLaws.laws(SequenceKW.semigroupK(), applicative, Eq.any()))

and it failed

java.lang.AssertionError: Property failed for
SequenceKW(sequence=kotlin.collections.ArraysKt___ArraysKt$asSequence$$inlined$Sequence$1@5d5abcb9)
SequenceKW(sequence=kotlin.collections.ArraysKt___ArraysKt$asSequence$$inlined$Sequence$1@2973d20a)
SequenceKW(sequence=kotlin.collections.ArraysKt___ArraysKt$asSequence$$inlined$Sequence$1@1ec9a588))
	at io.kotlintest.properties.PropertyTestingKt.forAll(PropertyTesting.kt:43)
	at kategory.data.SequenceKWTest$$special$$inlined$laws$1.invoke(SemigroupKlaws.kt:17)
	at kategory.data.SequenceKWTest$$special$$inlined$laws$1.invoke(SemigroupKlaws.kt:6)
	at io.kotlintest.Spec$runTest$callable$1$1.invoke(Spec.kt:124)
	at io.kotlintest.Spec$runTest$callable$1$1.invoke(Spec.kt:15)
	at io.kotlintest.Spec$runTest$initialInterceptor$1$1.invoke(Spec.kt:116)
	at io.kotlintest.Spec$runTest$initialInterceptor$1$1.invoke(Spec.kt:15)
	at io.kotlintest.Spec.interceptTestCase(Spec.kt:78)
	at io.kotlintest.Spec$runTest$initialInterceptor$1.invoke(Spec.kt:116)
	at io.kotlintest.Spec$runTest$initialInterceptor$1.invoke(Spec.kt:15)
	at io.kotlintest.Spec$runTest$callable$1.call(Spec.kt:124)
	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
	at java.lang.Thread.run(Thread.java:745)

any thought?

[prat]

oh, maybe because Sequence is lazy? TIL:

sequenceOf(1) == sequenceOf(1)
false

sequenceOf(1).toList() == sequenceOf(1).toList()
true

[pakoito]

oh, so it was the equals override

[pakoito]

good

[prat]

it's Class kategory.data.SequenceKWTest

[prat]

so basically my code is fine but the problem is we can't test Sequence equality. (sequenceOf(1) == sequenceOf(1) is false)

[Eugenio]

Sequence can't be tested for equality because the sequence might be infinite!

[prat]

right, i took me awhile to figure that out. not intuitive to me. i mean in haskell [1] == [1] is True. (not a haskell expert, just saying)

[prat]

oh, just learned that 1 #:: Stream.empty == 1 #:: Stream.empty is also true in Scala. now i'm curious about kotlin decision

[Eugenio]

@prat I mean, how would you implement it though? You could make special cases like for emptiness, but that's it, you can't possibly describe any sequence in a way that can be compared without actually executing it