Molecule0.22.5 < Back

Packages

package root
Documentation/API for the Molecule library - a meta DSL for the Datomic database.
Manual | scalamolecule.org | Github | Forum
Definition Classes
root

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.
input		Input molecules awaiting input.
macros		Internal macros generating molecule code from custom DSL molecule constructs.
generic		Interfaces to generic information about datoms and Datomic database.
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 generic
Definition Classes
molecule
package index
Datomic Index APIs in Molecule.
Datomic Index APIs in Molecule.

Datomic maintains four indexes that contain ordered sets of datoms. Each of these indexes is named based on the sort order used:
- 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
Create an Index molecule by instantiating an Index object with one or more arguments in the order of the Index's elements. Datoms are returned as tuples of data depending of which generic attributes you add to the Index molecule:
```
// Create EAVT Index molecule with 1 entity id argument
EAVT(e1).e.a.v.t.get === List(
  (e1, ":Person/name", "Ben", t1),
  (e1, ":Person/age", 42, t2),
  (e1, ":Golf/score", 5.7, t2)
)

// Maybe we are only interested in the attribute/value pairs:
EAVT(e1).a.v.get === List(
  (":Person/name", "Ben"),
  (":Person/age", 42),
  (":Golf/score", 5.7)
)

// Two arguments to narrow the search
EAVT(e1, ":Person/age").a.v.get === List(
  (":Person/age", 42)
)
```
Definition Classes
generic
Note
The Molecule Index API's don't allow returning the whole Index/the whole database. So omitting arguments constructing the Index object (like EAVT.e.a.v.t.get) will throw an exception.
Please use Datomics API if you need to return the whole database Index:
conn.db.datoms(datomic.Database.EAVT)
See also
Tests for more Index query examples.
AEVT
AEVT_0
AEVT_1
AEVT_2
AEVT_3
AEVT_4
AEVT_5
AEVT_6
AEVT_7
AVET
AVET_0
AVET_1
AVET_2
AVET_3
AVET_4
AVET_5
AVET_6
AVET_7
EAVT
EAVT_0
EAVT_1
EAVT_2
EAVT_3
EAVT_4
EAVT_5
EAVT_6
EAVT_7
GenericAEVT
GenericAVET
GenericEAVT
GenericVAET
VAET
VAET_0
VAET_1
VAET_2
VAET_3
VAET_4
VAET_5
VAET_6
VAET_7

molecule.generic.index

VAET

trait VAET extends GenericNs

VAET reverse Index.

"The VAET index contains all and only datoms whose attribute has a :db/valueType of :db.type/ref. This is also known as the reverse index, since it allows efficient navigation of relationships in reverse." (from Datomic documentation)

Access the VAET Index in Molecule by instantiating a VAET object with one or more arguments and then add generic attributes:

// Say we have 3 entities pointing to one entity:
Release.e.name.Artists.e.name.get === List(
  (r1, "Abbey Road", a1, "The Beatles"),
  (r2, "Magical Mystery Tour", a1, "The Beatles"),
  (r3, "Let it be", a1, "The Beatles"),
)

// .. then we can get the reverse relationships with the VAET Index:
VAET(a1).v.a.e.get === List(
  (a1, ":Release/artists", r1),
  (a1, ":Release/artists", r2),
  (a1, ":Release/artists", r3),
)

// Narrow search with multiple arguments
VAET(a1, ":Release/artist").e.get === List(r1, r2, r3)
VAET(a1, ":Release/artist", r2).e.get === List(r2)
VAET(a1, ":Release/artist", r2, t7).e.get === List(r2)

Index attributes available:

e - Entity id (Long)
a - Full attribute name like ":Person/name" (String)
v - Value of Datoms (Any)
t - Transaction pointer (Long/Int)
tx - Transaction entity id (Long)
txInstant - Transaction wall clock time (java.util.Date)
op - Operation status: assertion (true) / retraction (false)

Source: VAET.scala
Note: The Molecule Index API's don't allow returning the whole Index/the whole database. So omitting arguments constructing the Index object (like VAET.v.a.e.t.get) will throw an exception.
Please use Datomics API if you need to return the whole database Index:
conn.db.datoms(datomic.Database.VAET)
See also: Tests for more Index query examples.

Linear Supertypes

GenericNs, AnyRef, Any

Known Subclasses

VAET, VAET_0, VAET_1, VAET_2, VAET_3, VAET_4, VAET_5, VAET_6, VAET_7

Type Hierarchy

Ordering

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By Inheritance

Inherited

VAET
GenericNs
AnyRef
Any

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Protected

Type Members

final class a[Ns, In] extends OneString[Ns, In] with Indexed
(Partition)-Namespace-prefixed attribute name (":part_Ns/attr")
final class e[Ns, In] extends OneLong[Ns, In] with Indexed
Entity id (Long)
final class op[Ns, In] extends OneBoolean[Ns, In] with Indexed
Transaction operation: assertion (true) or retraction (false)
final class t[Ns, In] extends OneLong[Ns, In] with Indexed
Transaction point in time t (Long/Int)
final class tx[Ns, In] extends OneLong[Ns, In] with Indexed
Transaction entity id (Long)
final class txInstant[Ns, In] extends OneDate[Ns, In] with Indexed
Transaction wall-clock time (Date)
final class v[Ns, In] extends OneAny[Ns, In] with Indexed
Datom value (Any)

Value Members

final def !=(arg0: Any): Boolean
Definition Classes
AnyRef → Any
final def ##: Int
Definition Classes
AnyRef → Any
final def ==(arg0: Any): Boolean
Definition Classes
AnyRef → Any
final def asInstanceOf[T0]: T0
Definition Classes
Any
def clone(): AnyRef
Attributes
protected[lang]
Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.CloneNotSupportedException]) @native()
final def eq(arg0: AnyRef): Boolean
Definition Classes
AnyRef
def equals(arg0: AnyRef): Boolean
Definition Classes
AnyRef → Any
def finalize(): Unit
Attributes
protected[lang]
Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.Throwable])
final def getClass(): Class[_ <: AnyRef]
Definition Classes
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Annotations
@native()
def hashCode(): Int
Definition Classes
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Annotations
@native()
final def isInstanceOf[T0]: Boolean
Definition Classes
Any
final def ne(arg0: AnyRef): Boolean
Definition Classes
AnyRef
final def notify(): Unit
Definition Classes
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@native()
final def notifyAll(): Unit
Definition Classes
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@native()
final def synchronized[T0](arg0: => T0): T0
Definition Classes
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def toString(): String
Definition Classes
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final def wait(): Unit
Definition Classes
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Annotations
@throws(classOf[java.lang.InterruptedException])
final def wait(arg0: Long, arg1: Int): Unit
Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.InterruptedException])
final def wait(arg0: Long): Unit
Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.InterruptedException]) @native()

Packages

Sub-packages

VAET

trait VAET extends GenericNs

Type Members

Value Members

Inherited from GenericNs

Inherited from AnyRef

Inherited from Any

Ungrouped

Packages

Sub-packages

VAET

trait VAET extends GenericNs

Type Members

Value Members

Inherited from GenericNs

Inherited from AnyRef

Inherited from Any

Ungrouped

VAET