Easy pipeline debugging with curried console.log

average-triangle-1.js

import * as R from 'ramda';

const multiplySides = R.reduce(R.multiply, 1);
const divideByTwo = R.divide(2);

const averageTriangle = R.pipe(
  R.map(multiplySides),
  R.map(divideByTwo),
  R.mean
);

average-triangle-arrow.js

const averageTriangle = R.pipe(
  R.map(multiplySides),
  R.tap(data => console.log('mult', data)),
  R.map(divideByTwo),
  R.tap(data => console.log('div', data)),
  R.mean
);

average-triangle-tap-log.js

const averageTriangle = R.pipe(
  R.map(multiplySides),
  R.tap(log('mult')),
  R.map(divideByTwo),
  R.tap(log('div')),
  R.mean
);

average-triangle-tap.js

const averageTriangle = R.pipe(
  R.map(multiplySides),
  R.tap(console.log),
  R.map(divideByTwo),
  R.tap(console.log),
  R.mean
);

average-triangle-test.js

expect(averageTriangle([[2, 4], [3, 3], [4, 8]])).toBeCloseTo(8.167, 3);

average-triangle.js

const multiplySides = R.reduce(R.multiply, 1);
const divideByTwo = R.divide(2);

const averageTriangle = R.pipe(
  R.map(multiplySides),
  log('mult'),
  R.map(divideByTwo),
  log('div'),
  R.mean
);

log.js

// Javascript
export const log = (...args) => (data) => {
  console.log.apply(null, args.concat([data]));
  return data;
};

log.ts

// Typescript
export const log = (...args: any[]) => <T>(data: T): T => {
  console.log.apply(null, args.concat([data]));
  return data;
};

pipe-example.js

// RxJS
clickObservable
  .filter(isGood)
  .map(toThing)
  .flatMap(saveThing(apiService))
  .delay(100)
  .subscribe(setThing)

// Ramda
R.pipe(
  R.filter(isGood),
  R.map(toThing),
  R.groupBy(thingType(types))
)(data)

// lodash/fp
_.flow(
  _.filter(isGood),
  _.map(toThing),
  _.groupBy(thingType(types))
)(data)

rxjs-do.js

triangleObservable
  .do(log('triangles'))
  .map(averageTriangle)
  .do(log('average'))

triangle-log-1.txt

LOG: [8, 9, 32]
LOG: [0.25, 0.2222222222222222, 0.0625]
Chrome 62.0.3202 (Mac OS X 10.12.6) averageTriangle calculates the average area FAILED

triangle-success-log.txt

LOG: 'mult', [8, 9, 32]
LOG: 'div', [4, 4.5, 16]
Chrome 62.0.3202 (Mac OS X 10.12.6): Executed 4 of 4 SUCCESS (0.124 secs / 0.115 secs)

triangle-tagged-log.txt

LOG: 'mul', [8, 9, 32]
LOG: 'div', [0.25, 0.2222222222222222, 0.0625]
Chrome 62.0.3202 (Mac OS X 10.12.6) averageTriangle calculates the average area FAILED
        Expected 0.17824074074074073 to be close to 8.167, 3.