Learning FP via arrow-kt. Could be right, could be wrong! 🤷

MapView.kt

class MapView: Fragment(), MapReadyListener, LocationFoundListener {
    @Inject lateinit var mappable: Mappable
    @Inject lateinit var runtimePermissions: Set<String>
    
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        checkPermissions(requireActivity())
    }

    private fun checkPermissions(parentActivity: Activity) {
        runtimePermissions.map { permission ->
            Either.cond(
                    checkSelfPermission(parentActivity, permission) != PackageManager.PERMISSION_GRANTED,
                    { permission },
                    { permission }
            ).getOrElse{""}
        }.filterNot {
            it.isEmpty()
        } pipe { permissionsToRequest ->
            requestPermissions(permissionsToRequest.toTypedArray(), PERMISSION_REQUEST_CODE)
        }
    }

    override fun onRequestPermissionsResult(
            requestCode: Int,
            permissions: Array<out String>,
            grantResults: IntArray) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults)
        permissions.mapIndexed { index, requestedPermission ->
            Either.cond(
                    grantResults[index] != PackageManager.PERMISSION_GRANTED,
                    { when(requestedPermission) {
                        Manifest.permission.ACCESS_FINE_LOCATION -> getString(R.string.location_deny_nag_label)
                        Manifest.permission.WRITE_EXTERNAL_STORAGE -> getString(R.string.write_external_deny_nag_label)
                        else -> requestedPermission }
                    },
                    { mappable.refresh() }
            ).getOrElse{""}
        }.filterNot {
            it.isEmpty()
        }.pipe { rejectedPermissionMessages ->
            when(rejectedPermissionMessages.size) {
                1 -> (activity as AbstractAppCompatActivity)
                        .showPermissionsSnackbar(
                                rejectedPermissionMessages.first(),
                                Snackbar.LENGTH_LONG,
                                getString(R.string.settings_label)
                        )
                else -> (activity as AbstractAppCompatActivity)
                        .showPermissionsSnackbar(
                                getString(R.string.all_denied_permission_label),
                                Snackbar.LENGTH_INDEFINITE,
                                getString(R.string.settings_label)
                        )
            }
        }
    }
}