Fact type (joe)

An ad hoc type for Nero facts, consisting of a relation name and ordered or named fields. A Nero ruleset produces Fact values by default, and also accepts Facts as input. Many Joe values can be converted to Facts.

Static Methods

Initializer

Methods

Fact Fields and Field Names

A Fact's field values are accessible by the fields() method if the Fact isOrdered(), and as a map of field names and values via the fieldMap() method.

In addition, a fact's fields can be access as normal Joe object fields:

// Simple ordered fact; field names are `f1` and `f2`.
var fact = Fact("Thing", #car, #red);

// Prints "This Thing is #red"
println("This " + fact.relation() + " is " + fact.f2);

// Simple unordered fact; field names are as given.
var fact2 = Fact.ofMap("Thing", {"id": #car, "color": #red});

// Prints "This Thing is #red"
println("This " + fact.relation() + " is " + fact.color);

Static Methods

Fact.of()

Fact.of(relation, fields)

Creates a new ordered Fact given the relation and a list of field values. Its fields will be named f0, f1, etc.

The Fact will be an instance of the Java ListFact class.

Fact.ofMap()

Fact.ofMap(relation, fieldMap)

Creates a new unordered Fact given the relation and the field map. Its fields will have the names given as keys in the map.

The Fact will be an instance of the Java MapFact class.

Fact.ofPairs()

Fact.ofPairs(relation, pairs)

Creates a new ordered Fact given a flat list of field name/value pairs. Its fields will have the names given in the list.

The Fact will be an instance of the Java RecordFact class.

Fact Initializer

Fact(relation, field, ...) → Fact

Creates a new Fact given the relation and one or more the field values. Its fields will be named f0, f1, etc.

The Fact will be an instance of the Java ListFact class.

Methods

fact.fieldMap()

fact.fieldMap() → Map

Returns a read-only map of the field values.

fact.fields()

fact.fields() → List

Returns a read-only list of the field values, if the fact isOrdered().

fact.isOrdered()

fact.isOrdered() → Boolean

Returns true if the fact has ordered fields, and false otherwise.

fact.relation()

fact.relation() → String

Returns the Fact's relation name.

fact.toString()

fact.toString() → String

Returns the value's string representation.