endless.core.entity.StateReader.scala Maven / Gradle / Ivy
package endless.core.entity
/** `StateReader[F, S]` is the ability to read a value of type `S` from a shared environment in
* context `F`, where that value is semantically understood as the current state of the entity.
*
* Note that this is equivalent to `Ask[F, S]` in
* [[https://typelevel.org/cats-mtl/mtl-classes/ask.html cats mtl]].
*
* @tparam F
* context
* @tparam S
* state
*/
trait StateReader[F[_], S] {
/** Read the entity state, returns None if the entity doesn't yet exist
* @return
* optional state in `F` context
*/
def read: F[Option[S]]
}