@gram-data/gram-format NPM

DEPRECATED

This package has broken up into smaller, focused packages.

gram-format

This is the Gram data interchange format. Gram is a lightweight data graph. This textual representation is easy to read and write.

Data Graphs in Gram

Gram data comes in two parts:

Records which contain data values
Paths which compose records into structures

A gram file is a sequence of paths, making it ideal for streaming.

Let's create some data...

Unit Path, an empty path

The smallest amount of data is no data, put in a container so we know it is there. An empty path is infinite nothingness.

Empty path constructions:

[]
[] + [] = []
[ [] [] ] = []

As a special case, a single nest path implies composition with an empty path:

[ [] ] = [ [] [] ] = []

Identity:

identityof [] = undefined || all the same?

Nodes, a named path of length 0

When given a name, a path can be identified and described and discussed. The smallest named path has a special name in graphs. It is called a Node.

To help identify Nodes they can use special notation using parenthesis.

Node constructions:

[n]
(n) =~ [n]
() != []

The empty parenthesis expression is not an empty path. Nodes always have identity. The identity is simply unknown. Implementations may invent an identity, but must guarantee that it is unique across all paths.

Node compositions with units:

(n) + []   =~ [ + n _ ]  =~ [n] =~ (n)
[]  + (n)  =~ [ + _ n ]  =~ [n] =~ (n)

Identity:

identityof (n) =~ n
identityof ()  =~ <auto>

Edges, named paths of length 1

Nodes can be composed together to create a new path called an Edge.

Edge construction:

e = (n) + (n)  =~ [e + n n ]
e = (n1) + (n2) =~ [e + n1 n2]

That + is a placeholder for any path composition operator. Edges use operators that define the navigability of the path.

Edge operators:

--> right association
<-- left association
-- either direction

The edge operators can include the name of the edge.

Identity:

e =~ ()-->() =~ ()-[e]->() =~ [e --> () ()]

Paths, general composition

Paths generalize nodes and edges, allowing composition of any path-like structure into larger structures. By using binary composition, this forms a tree-like nesting of paths within paths.

Path construction:

p =~ (1)-->(2)<--(3) =~ [p -->  (1) [e <-- (2) (3)] ] =~ [p <-- [e --> (1) (2)] (3) ] ]

Paths can use any of the navigability operators used by edges, and also a special 'pair' operator which associates two path-like elements without explicitly connecting them.

Path composition without an explicit operator implies the , pair operator:

p =~ [p [p1] [p2]] =~ [p , [p1] [p2] ]

Identitity:

identityof [p + n n2] =~ p
identityof [  + n n ] =~ <auto>

Sequence, a list or stream of paths

Really just a convenience for a path of paths, optimized for processing.

Process how? Reduce a sequence to a node list or an edge list. Together, those two lists become a graph.

For fun take different windows of the sequence to see a graph at different points in time.

Graphs, a merged view of all paths

A graph is a view of all the paths. Mhmm.

Records, type-safe nested data values

JSON-like nested structures:

{
  name: 'Andreas',
  birthDay: date'1969-01-07',
  height: 184cm
  nicknames: ['abk']
}

Identifiers and Symbols

Identifier alphabet:

0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_@

Identifier regex: /[0-9a-zA-Z_@]+\b@*/

Symbol alphabet:

0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ

Symbol regex: /[a-zA-Z_][0-9a-zA-Z_]*\b(?!@)/

Cypher and GQL compatibility

For compatibility with Cypher and GQL statements, identifiers should be restricted to valid symbols.

Exploration...

// unary path operations
[p [u]] =~ [p]
[p [e]]
[p (n)]
[p [p2]]
[p [p]] =~ [p]

// binary path operations with unit produce the non-unit operand
(n) =~ (n) . []
(n) =~ []  . (n)
[e] =~ [e] . []
[e] =~ []  . [e]
[p] =~ [p] . []
[p] =~ []  . [p]

// binary path operations with non-unit
[p [e]  . [p2]]  =~ [e]  . [p2]
[p [e]  . [e] ]  =~ [e]  . [e]
[p [e]  . (n) ]  =~ [e]  . (n)
[p (n)  . [p2]]  =~ (n)  . [p2]
[p (n)  . [e] ]  =~ (n)  . [e]
[p (n)  . (n) ]  =~ (n)  . (n)   // aka an edge!
[p [p1] . [p2]]  =~ [p1] . [p2]
[p [p1] . [e]]   =~ [p1] . [e]
[p [p1] . (n)    =~ [p1] . (n)