The simplest way of bringing in the molecule api is with this import
import molecule.datomic.api._
This enable molecules with any arity.
If your code starts to have huge numbers of molecules, you can save time on compilation by importing a specialized Molecule api that sets a threshold for how many attributes are allowed in a molecule. This minimizes the amount of implicits waiting in vain to serve you and can reduce compilation time.
So, if your longest molecule in a code file has 7 attributes, then you could for instance set the api import to allow for 7 attributes:
import molecule.datomic.api.out7._
// The above specialized import would be enough to allow this or smaller molecules:
Person.e.firstName.lastName.age.Address.street.zip.city.get
Varying api arities can be set for each code file.
The Molecule library has more than 1300 tests with easily 30-100 molecules each, and we have simply set the api import to match the highest molecule arity in each file.
If you use input molecules then you can add inX where X is how many inputs (1, 2 or 3) your molecule expects:
import molecule.datomic.api.in2_out4._
// The above specialized import would be enough to allow this input molecule:
val personsOfAgeGender = m(Person.firstName.lastName.age_(?).gender_(?).Address.street.zip)
val male22 = personsOfAgeGender(22, "male").get
Molecule transparently optimize all queries sent to Datomic.
Most selective Clauses are automatically grouped first in the :where section of the Datomic query as per the recommendation in Datomic Query Best Practices.
This brings dramatic performance gains of in some cases beyond 100x compared to un-optimized queries. The optimization happens automatically in the background so that you can focus entirely on your domain without concern for the optimal order of attributes in your molecules.