Mangle Datalog

Mangle Datalog is a logic programming language and deductive database system.

Data is represented as facts. A fact combines several values into a logical statement, like a row in a table. Rules describes how to compute new facts from existing facts.

• Mangle is declarative: users communicate to the system what they want, not a series of commands.

• values can be structured data types like lists, maps, records (structs).

• programs can be split into modules, benefit from static type checking and type inference.

• it offers support for more complex queries that involve aggregation and function calls.

A first example

Here is an example describing a family from a Greek tragedy, Antigone:

parent(/oedipus, /antigone).
parent(/oedipus, /ismene).
parent(/oedipus, /eteocles).
parent(/oedipus, /polynices).

sibling(Person1, Person2) ⟸
   parent(P, Person1), parent(P, Person2), Person1 != Person2.

We state a few parent facts that describe the state of the world. The sibling rule describes when two people are siblings. We can now load this program and ask who Antigone’s siblings are:

mg >? sibling(/antigone, X)
sibling(/antigone,/eteocles)
sibling(/antigone,/ismene)
sibling(/antigone,/polynices)
Found 3 entries for sibling(/antigone,_).

Here X is a variable, ? sibling(/antigone, X) is a query asking for all possible values of X.

Documentation is under construction. In the meantime, please see the docs in the documentation and examples directory for more information.

Table of contents

• Installing
  • Installing the go implementation
  • Building the go implementation from source
  • Building the rust implementation from source
• Getting to know Datalog
  • Atoms and Matching
  • Multiple atoms and multiple rules
  • Recursive rules
  • The Safety Condition
  • Naive evaluation
• Aggregation
  • Grouping
  • Absence of values and Negation
• Basic Types
  • Names
  • Numbers
  • Floating-point Numbers
  • Strings
  • Byte strings
  • Time
  • Duration
• Constructed Types
  • Pairs
  • Tuples
  • Lists
  • Maps
  • Structs
• Type Expressions
  • Type variables
  • Any type
  • Singleton types
  • Union types
  • Constructed type expressions
  • Struct types
  • Tagged union types
  • Definition of type expressions
• Declarations
  • Syntax
  • Bound declarations
  • Descriptors
  • Combining bounds and rules
• Temporal Reasoning
  • Temporal Facts
  • Temporal Operators
  • Evaluation Time and “now”
  • Allen’s Interval Relations
  • Interval Functions
  • Interval Variable Binding
  • Interval Coalescing
  • Temporal Declarations
  • Example: Checking Certification Compliance
  • Programmatic Usage
  • Time Bridge Functions
  • Decidability and Termination
• Provenance
  • A first example
  • Multiple derivations
  • Provenance as queryable data
  • Negation
  • Simple and full modes
  • What is still not explained
  • Caps and performance
  • Using the Go API