pirj

You won’t find rants on how functional programming improves you, your sanity and your life overall here. There are some examples in the very beginning to save you some time on reading the whole post, just come along if you don’t like how they look like.

By the way, this is not even a blog, so formally this is not even a blog post. This is not a library or a new paradigm. It’s just a few pieces of code that might come handy for your daily job.

Example:

[1, 3.14, -4].map &_.safe{ magnitude odd? } # => [true, nil, false]

wvengen

Finding a Ruby memory leak using a time analysis

When developing a program in Ruby, you may sometimes encounter a memory leak. For a while now, Ruby has a facility to gather information about what objects are laying around: ObjectSpace.

There are several approaches one can take to debug a leak. This discusses a time-based approach, where a full memory dump is generated every, say, 5 minutes, during a time that the memory leak is showing up. Afterwards, one can look at all the objects, and find out which ones are staying around, causing the

RadhikaG

def parent(i):
    return i/2

def left(i):
    return 2*i

def right(i):
    return (2*i + 1)

class Heap:

RadhikaG

global heap
global currSize

def parent(i): #returns parent index of ith index
    return i/2

def left(i): #returns left child of ith index
    return 2*i

def right(i): #returns right child of ith index

ChuckJHardy

class MyJob < ActiveJob::Base
  queue_as :urgent

  rescue_from(NoResultsError) do
    retry_job wait: 5.minutes, queue: :default
  end

  def perform(*args)
    MyService.call(*args)
  end

pixeltrix

When should you use DateTime and when should you use Time?

It's a common misconception that [William Shakespeare][1] and [Miguel de Cervantes][2] died on the same day in history - so much so that UNESCO named April 23 as [World Book Day because of this fact][3]. However because England hadn't yet adopted [Gregorian Calendar Reform][4] (and wouldn't until [1752][5]) their deaths are actually 10 days apart. Since Ruby's Time class implements a [proleptic Gregorian calendar][6] and has no concept of calendar reform then there's no way to express this. This is where DateTime steps in:

>> shakespeare = DateTime.iso8601('1616-04-23', Date::ENGLAND)
=> Tue, 23 Apr 1616 00:00:00 +0000
>> cervantes = DateTime.iso8601('1616-04-23', Date::ITALY)
=> Sat, 23 Apr 1616 00:00:00 +0000

janko

require "active_record"

ActiveRecord::Base.establish_connection('postgres:///testing')
ActiveRecord::Migration.verbose = false

ActiveRecord::Migration.class_eval do
  create_table :played_quizzes, force: true do |t|
    t.integer :player_ids, array: true
    t.json    :quiz_snapshot
  end

mr-linch

#!/usr/bin/env python3

import csv
import urllib.request

from bs4 import BeautifulSoup


BASE_URL = 'http://www.weblancer.net/projects/'

lolzballs

import java.io.FileDescriptor;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.io.PrintStream;

public class HelloWorld{
	private static HelloWorld instance;
    public static void main(String[] args){
        instantiateHelloWorldMainClassAndRun();

itsthatguy

# Run the following command in shell:
# curl -s https://gist.githubusercontent.com/itsthatguy/48d9b47dba05b300c65b/raw/80b1111bb5273697d1db4f5662eb763aa4a80cdc/foo.coffee | coffee --stdio
class Foo
  name: 'abott'
  @myFunction: ->
    console.log "\n# start"
    console.log "\nFoo"
    console.log "this.name:", this.name
  myOtherFunction: ->
    console.log "\nfoo (instance of Foo)"