| layout | title | permalink |
|---|---|---|
docs-optics |
Snoc |
/optics/snoc/ |
Snoc provides a [Prism]({{ '/optics/prism' | relative_url }}) between S and its init A and last element S.
Snoc can be seen as the reverse of [Cons]({{ '/optics/cons' | relative_url }}); it provides a way to attach or detach elements on the end side of a structure.
It can be constructed by providing the Prism.
import arrow.core.ListK
import arrow.optics.extensions.listk.snoc.snoc
import arrow.optics.typeclasses.Snoc
val listLast = ListK.snoc<Int>().snoc()
val instance = Snoc(listLast)
instance
It defines two functions snoc and unsnoc.
snoc appends an element A to a structure S.
import arrow.optics.extensions.list.snoc.snoc
listOf(1, 2).snoc(3)
unsnoc detaches the last element A from a structure S.
import arrow.optics.extensions.list.snoc.unsnoc
listOf(1, 2, 3).unsnoc()
emptyList<Int>().unsnoc()