purescript-teller

Teller provides trend identification and forecasting facilities based on bank transactions. Teller can be used from both Purescript and Javascript/Typescript.

Installation

Purescript

Documentation is published on Pursuit.

Javascript & Typescript

npm install teller-js

Teller provides its own Typescript definitions

Examples

Trends

// Given some transaction data
import {
  identifyTrends,
  isSpecificWeekdayTrendDescription,
  isEveryWeekdayTrendDescription,
} from "teller-js";

const transactions = [
  {
    accountId: "8Ybo8ppEBrHxJM45p7koSvaKQnM341fyMKQwO",
    timestamp: 1586473200000.0,
    amount: 0.01,
    merchantName: "Asda",
    reference: "Asda",
  },
  ...{
    accountId: "8Ybo8ppEBrHxJM45p7koSvaKQnM341fyMKQwO",
    timestamp: 1586300400000.0,
    amount: -60.0,
    merchantName: "201053 53364402 MOBILE-CHANNEL FT",
    reference: "201053 53364402 MOBILE-CHANNEL FT",
  },
];

const result = identifyTrends(transactions);

result.forEach((tr) => {
  const merchant = tr.value0;
  const trend = tr.value1;

  // See dist/index.d.ts for a full list of all potential trend description types

  if (isEveryWeekdayTrendDescription(trend)) {
    console.log(`${merchant} transaction happens every day`);
  }

  if (isSpecificWeekdayTrendDescription(trend)) {
    // Monday is 1, Sunday is 7
    const days = ["mon", "tue", "wed", "thu", "fri", "sat", "sun"];

    console.log(
      `${merchant} transaction happens every ${days[trend.value0.weekday - 1]}`
    );
  }
});

Further Work

Surface algorithm confidence as a percentage in the trend description result
Return the prediction for the price that will be paid given a trend so the trend can be used for prediction
Given a start and an end date forecast spending income and balance for each day in the period
Given a set of transactions and a trend identify if the trend is holding recently
Treat identified trends as fixed costs and provide a estimation of a persons monthly fixed costs