jrsinclair

const countSubstringMatches = (str: string, substr: string, startAt: number) => {
  const substringLength = substr.length;
  let count = 1;
  for (
    let substringPos = str.indexOf(substr, startAt + substringLength);
    substringPos >= 0;
    ++count
  )
    substringPos = str.indexOf(substr, substringPos + substringLength);
  return count;

jrsinclair

const dangerousPushAll = (xs, ys) => {
  for (const y in ys) {
    xs.push(y);
  }
  return xs;
}

jrsinclair

// @flow strict-local

// Lenses
// ------------------------------------------------------------------------------------------------

export type LensInternal<S, T, A, B> = {
    getVal: (S) => A,
    setVal: (B, S) => T,
};

jrsinclair

import fs from 'fs';

const data = fs.readFileSync('/path/to/my/copy/of/input.txt');
const input = data.toString('utf-8').split('\n').filter(x => x !== '').map(x => parseInt(x));

// Chop goes through the array, but gives you less and less of it each time. If you fed it [1, 2, 3], then
// the first iteration would get [1, 2, 3], the next would get [2, 3] and the final would get [3]. Idea is stolen
// from fp-ts: https://gcanti.github.io/fp-ts/modules/ReadonlyArray.ts.html#chop
const chop = (f) => (arr) => [...(new Array(arr.length))].map((_, i) => f(arr.slice(i)));

jrsinclair

const setAttr = _.curry((attrName, el, val) => { el.setAttribute(val)); return el; });

const listen = _.curry((evtName, el, f) => { el.addEventListener(evtName, f); return el; })

const bindCreateResultButton = (createResultButton, postTextarea, getPostData, preTextarea) =>
    _.compose(
        listen('click', createResultButton),
        _.compose(x => () => setAttr('value', postTextArea, x), getPostData),
    )(preTextArea);

jrsinclair

function csvToMessages(csvData) {
    const csvRows      = splitCSVToRows(csvData);
    const headerFields = csvRows.map(_.head).map(splitFields);
    const dataRows     = csvRows.map(_.tail);
    const processRowsA = liftA2(processRows);
    const messagesArr  = processRowsA(headerFields, dataRows);
    return either(showError, showMessages, messagesArr);
}

jrsinclair

function liftA2(func) {
    return function runApplicativeFunc(a, b) {
        return b.ap(a.map(func));
    };
}

jrsinclair

function csvToMessages(csvData) {
    const csvRows      = splitCSVToRows(csvData);
    const headerFields = csvRows.map(_.head).map(splitFields);
    const dataRows     = csvRows.map(_.tail);
    const funcInEither = headerFields.map(processRows);
    const messagesArr  = dataRows.ap(funcInEither);
    return either(showError, showMessages, messagesArr);
}

jrsinclair

/* Rest of Left class is hidden to save space */

    // Ap In Left (the sad path)
    ap() {
        return this;
    }

jrsinclair

function csvToMessages(csvData) {
    const csvRows      = splitCSVToRows(csvData);
    const headerFields = csvRows.map(_.head).map(splitFields);
    const dataRows     = csvRows.map(_.tail);

    // How will we pass headerFields and dataRows to
    // processRows() ?
    const funcInEither = headerFields.map(processRows);
}