RDF/JSON -> Turtle serialiser w/ Ramda

turtle-serialiser.js

var prepend = first => second => first + second
, prefix = (item, i) => `@prefix n${i}: <${item}> . \n`
, mapI = R.addIndex(R.map)
, insertIndex = (ns,uri) => ns.push(uri)-1
,  nsEnd = uri => Math.max(uri.lastIndexOf('#'), uri.lastIndexOf('/')) +1
,  lookup = ns => uri => { const i = ns.indexOf(uri); return 'n' +  (i>-1)? i : insertIndex(ns,uri) }
,  change0 = R.over(R.lensIndex(0))
,  change1 = R.over(R.lensIndex(1))
,  literal = ({value,lang,datatype}) => '"'+ value.replace(/("|\n)/g,'\\$1') + '"'+langTag(lang)+dataType(datatype)
,  langTag = lang => lang? '@'+lang : ''
,  dataType = dt => dt? '^^'+dt : ''
,  uri = ns => u => R.pipe(R.splitEvery(nsEnd(u)), change0(lookup(ns)), R.join(':'))(u)
,  typeIs = R.propEq('type')
,  obj = ns => R.cond([
 [typeIs('literal'), literal]
,[typeIs('uri'), R.pipe(R.prop('value'),uri(ns))]
])
,  objectValues = ns => R.pipe(R.map(obj(ns)), R.join(', '))
,  propObjects = ns => R.pipe(change0(uri(ns)), change1(objectValues(ns)), R.join(' '))
,  props = ns=> R.pipe(R.toPairs, R.map(propObjects(ns)), R.join('\n;\t'))
,  subProps = ns => R.pipe(change0(uri(ns)), change1(props(ns)), R.join(' '))
,  turtle = (data, ns=[]) =>  {
    const body = R.pipe(R.toPairs, R.map(subProps(ns)), R.join(' .\n') )(data)
    return mapI(prefix,ns) + body
}