jrsinclair

function processRows(headerFields) {
    return function processRowsWithHeaderFields(dataRows) {
        // Note this is Array map, not Either map.
        return dataRows.map(row => processRow(headerFields, row));
    };
}

jrsinclair

function csvToMessages(csvData) {
    const csvRows      = splitCSVToRows(csvData);
    const headerFields = csvRows.map(_.head).map(splitFields);
    const dataRows     = csvRows.map(_.tail);
    // What’s next?
}

jrsinclair

function splitCSVToRows(csvData) {
    // There should always be a header row... so if there's no
    // newline character, something is wrong.
    return (csvData.indexOf('\n') < 0)
        ? left('No header row found in CSV data')
        : right(csvData.split('\n'));
}

function processRows(headerFields, dataRows) {
    // Note this is Array map, not Either map.

jrsinclair

function processRow(headerFields, row) {
    const rowObjWithDate = right(row)
        .map(splitFields)
        .chain(zipRow(headerFields))
        .chain(addDateStr);
    return either(showError, rowToMessage, rowObjWithDate);
}

jrsinclair

function processRow(headerFields, row) {
    const fieldsEither   = right(row).map(splitFields);
    const rowObj         = fieldsEither.chain(zipRow(headerFields));
    const rowObjWithDate = rowObj.chain(addDateStr);
    return either(showError, rowToMessage, rowObjWithDate);
}

jrsinclair

function processRow(headerFields, row) {
    const fieldsEither   = right(row).map(splitFields);
    const rowObj         = fieldsEither.chain(zipRow(headerFields));
    const rowObjWithDate = rowObj.chain(addDateStr);
    // Slowly getting better... but what do we return?
}

jrsinclair

function either(leftFunc, rightFunc, e) {
    return (e instanceof Left) ? leftFunc(e._value) : rightFunc(e._value);
}

jrsinclair

/**
 *Left represents the sad path.
 */
class Left {
    constructor(val) {
        this._value = val;
    }

    map() {
        // Left is the sad path

jrsinclair

function processRow(headerFields, row) {
    const fieldsEither   = right(row).map(splitFields);
    const rowObj         = fieldsEither.map(zipRow(headerFields)).join();
    const rowObjWithDate = rowObj.map(addDateStr).join();
    // Slowly getting better... but what do we return?
}

jrsinclair

/**
 *Left represents the sad path.
 */
class Left {
    constructor(val) {
        this._value = val;
    }

    map() {
        // Left is the sad path