@oggi.ch/pipe

Pipeline: make a chain of functions that the output will be the input of the next function.

Install

$ npm install @oggi.ch/pipe
or
$ yarn add @oggi.ch/pipe

Usage

const pipe = require('@oggi.ch/pipe');
pipe(
    initialValue,
    [...functions]
)

Examples

### Example 1

const pipe = require('@oggi.ch/pipe');

const double = a => a * 2;
const sum = (a, b) => a + b;
const minus = (a, b) => a - b;
const div = (a, b) => a / b;
const multiply = a => b => a * b;

const result_1 = pipe(
    6, 
    double,
    console.log,      // ← Debuggable 
    _ => sum(10, _), 
    _ => div(_, 3),
    console.log,     // ← Easy print intermediate result
    Math.floor, 
    multiply(6), 
    _ => minus(_, 3)
);

console.log('Result is', result_1);
-------------------------------------------------------------------------------
12
7.333333333333333
Result is 39

### Example 2

const cleanVowels = str => str.replace(/[aeiou]/ig, "");

const result_2 = pipe(
    "Lorem ipsum dolor sit amet.",
    cleanVowels,
    (_) => _.split(""),
    (_) => _.reverse(),
    (_) => _.join("")
);

console.log('Result is', result_2);
-------------------------------------------------------------------------------
Result is  .tm ts rld msp mrL

### Example 3

const reParser = /^(\S+) (\S+) (\S+) \[([\w:/]+\s[+\-]\d{4})\] "(\S+)\s?(\S+)?\s?(\S+)?" (\d{3}|-) (\d+|-)\s?"?([^"]*)"?\s?"?([^"]*)?"?$/;

const parseLogLines = (logs) => {
    return logs.map(log => {
        const parsed = log.match(reParser);
        return {
            ipAddress: parsed[1],
            datetime: moment(parsed[4], 'DD/MMM/YYYY:HH:mm:ss ZZ'),
            method: parsed[5],
            resource: parsed[6],
            protocol: parsed[7],
            status: parsed[8],
            size: parsed[9],
            referer: parsed[10],
            userAgent: parsed[11]
        }
    });
};

const trim = str => str.trim();
const split = token => str => str.split(token);
const take = key => items => ( items.map(item => item[key]) );
const grep = rule => items => ( items.filter(item => item.indexOf(rule) !== -1) );
const wc = items => items.reduce(totals => totals + 1, 0);

const accesslog = `
127.0.0.1 - - [21/Aug/2017:09:10:51 +0000] "GET / HTTP/1.1" 200 534 "" "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/61.0.3163.49 Safari/537.36"
127.0.0.1 - - [21/Aug/2017:09:10:53 +0000] "GET /admin HTTP/1.1" 200 534 "" "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/61.0.3163.49 Safari/537.36"
127.0.0.1 - - [21/Aug/2017:09:10:57 +0000] "GET / HTTP/1.1" 200 14 "" "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/61.0.3163.49 Safari/537.36"
127.0.0.1 - - [21/Aug/2017:09:10:58 +0000] "GET /admin HTTP/1.1" 200 534 "" "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/61.0.3163.49 Safari/537.36"
127.0.0.1 - - [21/Aug/2017:09:10:59 +0000] "GET /admin HTTP/1.1" 200 534 "" "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/61.0.3163.49 Safari/537.36"
`; 

const result_3 = pipe(
    accesslog,
    trim,
    split('\n'),
    parseLogLines,
    take('resource'),
    grep('/admin'),
    wc
);
console.log('Result is', result_3);
-------------------------------------------------------------------------------
Result is 3

### Example 4 (async)

const asyncDouble = a => new Promise((resolve, reject) => {
    setTimeout(() => {
        resolve(a * 2)
    }, 500);
});

const asyncAdd = (a, b) => new Promise((resolve, reject) => {
    setTimeout(() => {
        resolve(a + b)
    }, 100);
});

const result_4 = pipe(
    6,
    asyncDouble,
    (_) => (_ - 1),
    (_) => asyncAdd(_, 7)
);

console.log('Async result is...');
result_4.then(console.log)
-------------------------------------------------------------------------------
Async result is...
18