Packages

package root

Documentation/API for the Molecule library - a meta DSL for the Datomic database.

Manual | scalamolecule.org | Github | Forum

Definition Classes: root

package molecule

Molecule library - a Scala meta-DSL for the Datomic database.

See api package for various api imports to start using Molecule.

Sub-packages

api		Molecule API.
ast		Internal Molecule ASTs.
boilerplate		Internal interfaces for auto-generated DSL boilerplate code.
composition		Builder methods to compose molecules.
exceptions		Exceptions thrown by Molecule.
expression		Attribute expressions and operations.
facade		Molecule facades to Datomic.
factory		Implicit macro methods `m` to instantiate molecules from custom DSL molecule constructs.
generic		Interfaces to generic information about datoms and Datomic database.
input		Input molecules awaiting input.
macro		Internal macros generating molecule code from custom DSL molecule constructs.
ops		Internal operational helpers for transforming DSL to molecule.
schema		Schema definition DSL.
transform		Internal transformers from DSL to Model/Query/Transaction.
util		Internal Java database functions for Datomic.

Definition Classes: root

package api

Public interface to be imported to use Molecule.

To make the Molecule macro materializations as fast as possible we try to import as few macro implicits as possible. If your application code build molecules with at the most 10 attributes, then you can do the following import to start using Molecule:

import molecule.api.out10._

out means "output molecule" , and 10 the maximum arity or number of attributes of your molecules.

If you use input molecules awaiting an input then you can add inX where X is how many inputs (1, 2 or 3) you will use, for instance:

import molecule.api.in2_out10._

This way we keep the implicit macro def lookups to a minimum and compilation speed as fast as possible.

Arities can be changed anytime you like. But not to a lower arity than that of the molecules you use in scope of the import.

Definition Classes: molecule

package ast

Internal Molecule ASTs.

Definition Classes: molecule

package boilerplate

Internal interfaces for auto-generated DSL boilerplate code.

Internal interfaces for auto-generated DSL boilerplate code.

Interfaces to the generated schema-defined DSL boilerplate code that the sbt-plugin generates when doing a sbt-compile. Molecule macros can then type-safely deduct the type structure of composed molecules.

Definition Classes: molecule

package composition

Methods to build transaction, composite and nested molecules.

Definition Classes: molecule

package exceptions

Exceptions thrown by Molecule.

Definition Classes: molecule

package expression

Attribute expressions and operations.

Attribute expressions and operations.

Refine attribute matches with various attribute expressions:

Person.age(42)                           // equality
Person.name.contains("John")             // fulltext search
Person.age.!=(42)                        // negation (or `not`)
Person.age.<(42)                         // comparison (< > <= >=)
Person.name("John" or "Jonas")           // OR-logic
Person.age()                             // apply empty value to retract value(s) in updates
Person.hobbies.assert("golf")               // add value(s) to card-many attributes
Person.hobbies.retract("golf")            // retract value(s) of card-many attributes
Person.hobbies.replace("golf", "diving") // replace value(s) of card-many attributes
Person.tags.k("en")                      // match values of map attributes by key
Person.age(Nil)                          // match non-asserted datoms (null)
Person.name(?)                           // initiate input molecules awaiting input at runtime
Person.name(unify)                       // Unify attributes in self-joins

Apply aggregate keywords to aggregate attribute value(s):

// Aggregates on any attribute type
Person.age(count).get.head         === 3   // count of asserted `age` attribute values
Person.age(countDistinct).get.head === 3   // count of asserted distinct `age` attribute values
Person.age(max).get.head           === 38  // maximum `age` value (using `compare`)
Person.age(min).get.head           === 5   // maximum `age` value (using `compare`)
Person.age(rand).get.head          === 25  // single random `age` value
Person.age(sample).get.head        === 27  // single sample `age` value (when single value, same as random)

// Aggregates on any attribute type, returning multiple values
Person.age(distinct).get.head  === Vector(5, 7, 38)  // distinct `age` values
Person.age(max(2)).get.head    === Vector(38, 7)     // 2 maximum `age` values
Person.age(min(2)).get.head    === Vector(5, 7)      // 2 minimum `age` values
Person.age(rand(2)).get.head   === Stream(5, ?)      // 2 random `age` values (values can re-occur)
Person.age(sample(2)).get.head === Vector(7, 38)     // 2 sample `age` values

// Aggregates on number attributes
Person.age(sum).get.head      === 50               // sum of all `age` numbers
Person.age(avg).get.head      === 16.66666667      // average of all `age` numbers
Person.age(median).get.head   === 7                // median of all `age` numbers
Person.age(stddev).get.head   === 15.107025591499  // standard deviation of all `age` numbers
Person.age(variance).get.head === 228.2222222222   // variance of all `age` numbers

Definition Classes: molecule
See also: Manual: expressions | aggregates | input molecules
Tests: expressions

package facade

Molecule facades to Datomic.

Molecule facades to Datomic.

Facades are not trying to cover all Datomic methods but rather only interfaces relevant to Molecule.

Definition Classes: molecule

package factory

Factory methods m to instantiate molecules from custom DSL molecule constructs.

Definition Classes: molecule

package generic

Interfaces to get generic information about data and schema.

Datom - Generic Datom attributes in molecules
Log - Datoms sorted by transaction/time
EAVT - Datoms sorted by Entity-Attribute-Value-Transaction
AVET - Datoms sorted by Attribute-Value-Entity-Transaction
AEVT - Datoms sorted by Attribute-Entity-Value-Transaction
VAET - "Reverse index" for reverse lookup of ref types
Schema - Meta information about the current database schema.

Definition Classes: molecule

package input

Input molecules awaiting input.

Input molecules awaiting input.

Input molecules are molecules that awaits one or more inputs at runtime. When input value is applied, the input molecule is resolved and a standard molecule is returned that we can then call actions on.

Input molecule queries are cached by Datomic. So there is a runtime performance gain in using input molecules. Furthermore, input molecules are a good fit for re-use for queries where only a few parameters change.

Input molecules can await 1, 2 or 3 inputs and are constructed by applying the ? marker to attributes. If one marker is applied, we get a InputMolecule_1, 2 inputs creates an InputMolecule_2 and 3 an InputMolecule_3.

The three input molecule interfaces come in arity-versions corresponding to the number of non-?-marked attributes in the input molecule. Let's see a simple example:

// Sample data
Person.name.age insert List(("Ben", 42), ("Liz", 34))

// Input molecule created at compile time. Awaits a name of type String
val ageOfPersons: InputMolecule_1.InputMolecule_1_01[String, Int] = m(Person.name_(?).age)

// Resolved molecule. "Ben" input is matched against name attribute
val ageOfPersonsNamedBen: Molecule.Molecule01[Int] = ageOfPersons.apply("Ben")

// Calling action on resolved molecule.
// (Only age is returned since name was marked as tacit with the underscore notation)
ageOfPersonsNamedBen.get === List(42)

// Or we can re-use the input molecule straight away
ageOfPersons("Liz").get === List(34)

Definition Classes: molecule

package macros

Internal macros generating molecule code from custom DSL molecule constructs.

Definition Classes: molecule

package ops

Internal operational helpers for transforming DSL to molecules.

Definition Classes: molecule

package schema

Schema definition DSL and API.

Definition Classes: molecule

SchemaTransaction

definition

package transform

Internal transformers from DSL to Model/Query/Transaction/Datomic.

Internal transformers from DSL to Model/Query/Transaction/Datomic.

Molecule transforms custom boilerplate DSL constructs to Datomic queries in 3 steps:

Custom DSL molecule --> Model --> Query --> Datomic query string

Definition Classes: molecule
See also: http://www.scalamolecule.org/dev/transformation/

package util

Internal database functions for Datomic.

Definition Classes: molecule

molecule

schema

package schema

Schema definition DSL and API.

Source: package.scala

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trait SchemaTransaction extends AnyRef
Schema transaction interface for auto-generated schema transaction data.
Schema transaction interface for auto-generated schema transaction data.

See also
Manual

Value Members

object definition

Schema definition DSL.

Schema definition DSL.

Define Datomic database schema in a Schema Definition file.

For small projects, the schema can be defined without partition definitions where all namespaces reside in a default tacit partition:

package path.to.your.project
import molecule.schema.definition._       // import schema definition DSL

@InOut(1, 8)                              // Set input/output arity
object SeattleDefinition {                // Schema definition object

  trait Person {                          // Namespace
    val name = oneString.fulltext   // String attribute definition with fulltext search
    val age  = oneInt                     // Int attribute definition
  }

  // Additional namespaces...
}

For larger projects, it is recommended to group namespaces in partitions:

package path.to.your.project
import molecule.schema.definition._

@InOut(3, 15)
object SeattleDefinition {

  object customer {
    trait Person {
      val name    = oneString.fulltext
      val age     = oneInt
      val address = one[Address]
      val bought  = many[products.Item]
    }
    trait Address {
      val street = oneString.fulltext
      val city   = oneInt
    }
    // ..more namespaces in the `customer` partition
  }

  object products {
    trait Item {
      val title   = oneString
      val inStock = oneInt
    }
    // ..more namespaces in the `products` partition
  }

  // Additional partitions...
}

See also: Manual | Tests: Schema without partitions, Schema with partitions, Bidirectionals

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schema

package schema

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