Example Transducer for tim.js

click_position.js

// example of get the position of the cursor in a line of a text buffer from a click event

function clickPositionToCharIndex(clickX){
  return comp(
    map(measureCharWidth),
    reductions((a,b) => a + b, 0),
    takeWhile(x => x < clickX),
    mapIndexed((idx, item) => idx)
  );
}

//index of all the characters up to the click coord (i.e. x = 100)
const positions = transduce(clickPositionToCharIndex(100), array_push, [], textBuffer);

// the last one is the click position
const cursorPosition = positions[position.length - 1]; 

transducer_example.js

// long winded example of how we make pdfs from svgs 

function svgToPDFPipeline(host){
    return comp(
        map(tryUrlDecode),
        map(str => str.replace(" ", " ")),
        map(toByteStream),
        map(toXMLResource),
        map(removeNoScriptTag),
        map(processTextAnchor),
        map(processFillProperty),
        map(processStyle),
        map(processedFilteredText),
        map(partial(processPlaceHolderImage, host)),
        map(addXMLNS),
        map(svg => svgToString(svg))
    );
}

const pdfGenerationProcess = comp(
    svgToPDFPipeline("www.somehost.com"),
    map(toByteStream),
    map(inputStream => new TranscoderInput(inputStream)),
    timing // this is just a benchmark thing
);

const pdfGen = pdfGenerator(fontConfig, outputStream);

transduce(pdfGenerationProcess, pdfGen, arrayOfSvgs);