Gram - a lightweight graph exchange format

graph-exchange-format.gram

// gram is a lightweight graph exchange format.
// 
// gram is a series of path updates.
// 
// identified path elements may be introduced and referenced in a later update

// node shapes
()      // anonymous node
(a)     // identified node
(1)     // numerically identified node
(a1)    // alphanumerically identified node

(:Person)           // anonymous node with a label
(:Person:Stealthy)  // another anonymous node, with multiple labels


(2:Person) // new identified Person, with a label
(a:Person) // update to node 'a' with a label

(3 {ordinal:'third'}) // new identified node, with a single property
(4 {ordinal:'fourth', since:date`1999` })

// anonymous nodes with just properties
{org:'anonymous',size:5}
{name:'dan'}-{likes}->{name:'ann'}

// fun with number values
// In exponential notation, e or E defines a power-of-ten exponent for decimal values, and p or P defines a power-of-two exponent for non-decimal values, i.e. binary, hexadecimal or octal.

({size:4})                  // integer
({cm:180.6})                // decimal number
({:.375})                   // decimal without whole number
({bigDecimal:5032485723458348569331745.33434346346912144534543})

({science:4.321e+4)         // scientific notation is always a decimal '43210.0'
({science:-735.0918e-430)   // science can be negsative '-7.350918e-428'
({trailing:5.6700000})      // drop trailing zeroes '5.67'


// decimals within tagged string, containing digits or constants
// https://en.wikipedia.org/wiki/Mathematical_constant#Table_of_selected_mathematical_constants

({a:decimal`3.14`}) // decimal string using full tag
({a:d`3.1495`})     // decimal string with shorthand tag
({a:d`Infinity`}) 
({a:d`NaN`}) 

({a:d`tau`})        // 2*pi https://en.wikipedia.org/wiki/Turn_(angle)#Tau_proposals

({a:d`phi`})        // golden ratio
({a:d`golden`})     

({a:d`e`})
({a:d`i`})          
({a:d`pi`})

////
// alternate base representation of numbers
// 8-bit aligned

// hexadecimal
({guid:0x1337c001c4fe})    // hexadecimal integer values of arbitrary length
({toDecimal:0xff.8})       // hexadecimal decimal value '255.5'
({science:0x1.8p-5})       // '0.046875'

// binary
({mask:0b00110011})     // binary integer
({mask:0b110011})       // left-padded nibble '0b00110011'
({toDecimal:0b0.000011')  // '0.046875'
({science:0b1.1p-5})      // '0.046875'

// octal
({toDecimal:0o0.03)                   // '0.046875'
({science:0o1.4p-5})                  // '0.046875'


////
// fractions

({portion:frac`1/4`})
({rating:f`1/10`})
({ratio:f`1:1`})
({music:f`4/4`})
({precis:f`1/3`})

// Date, Time, Interval
// ISO 8601 compatible https://en.wikipedia.org/wiki/ISO_8601

// year
({year:date`1999`})                 // Date Year, always four digits

// year month day
({yearMonthDay:date`2020-01-01`})   // YYYY-MM-DD
{{yearMonthDay:date`20200101`}}     // YYYYMMDD drop hyphens

// year month
({yearMonth:date`2020-01`})         // YYYY-MM without day
({illegal:date:`202001`})           // YYYMM is illegal.

// month day
({monthDay:date`--12-30`})          // --MM-DD without year
({monthDay:date`--1230`})           // --MMDD without year is also ok

// week dates in the gregorian calendar
// week days are numbered 1-7
({weekDate:date`2020-W10`})         // YYYY-Www
({weekDate:date`2020W10`})          // YYYYWww drop hyphens but keep explicit 'W'
({weekDate:date`2020-W10-3`})       // YYYY-Www-D
({weekDate:date`2020W103`})         // YYYYWwwD drop hyphens

// ordinal dates
// days are numbered 1-366 (to accept leap years)
({ordinalDate:date`2020-001`})      // YYYY-DDD
({ordinalDate:date`2020001`})       // YYYYDDD


// CSS
({color:#daB671})           // css friendly hex colors
({color:color`blue`})       // css color names as tagged string
({color:color`#FF33DA})     // css hex color in tagged string

({lineHeight:unit`12 px`})  // numbers with units
({margin:u`0.5 em`})        // abbreviated unit tag


// text within text
({homepage:url`http://`})                               // this string is a url
({readme:md`# Mark down my words`})                     // this string is in markdown format
({page:html`<p>Wow, such stucture inside here!</p>`})   // or html
({math:tex`This formula $f(x) = x^2$ is an example.`})  // or latex

// template pattern lists. a template pattern followed by a list of value patterns

// For example:
// - a single node pattern
// - every node will get a `:Person` label
// - property tuples will be of the form: 
//   - name, a string
//   - birth, a Year
//   - favoriteColor, a css hex value
//   - home, a url string
$(:Person {name:``, birth:0y, favoriteColor:# home:url})

    // begin list of value patternsd
    (5 {'Leonhard Euler', 1707, 4d9Eda, 'http://euler.org'})    // all values present
    (6 {'Bob',_,_'http://neo4j.com'})                           // some values missing (using `_` placeholder)
    (7:Employee {'ABK'}) // extra label
    8,'ann',1998,'goldenrod','http://somewhere.com/ann'


$()-[:KNOWS]->()  // change template
    (5)-->(6)

$() // resets to no template (normal operation)